Marsh Life

About the Marsh

A Dyke Marsh inlet. Photo by Ned Stone.The Dyke Marsh Wildlife Preserve is a 485-acre freshwater, tidal wetland complex just south of Alexandria, Virginia, in Fairfax County, Virginia, on the western shoreline of the Potomac River around 95 miles from the Chesapeake Bay.  Congress added the preserve to the national park system in 1959 "so that fish and wildlife development and their preservation as wetland wildlife habitat shall be paramount."  (Public Law 86-41)

Dyke Marsh is one of the largest, most significant temperate, climax, narrow-leafed cattail marshes in the national park system, a unit of the George Washington Memorial Parkway managed by the National Park Service. It has tidal wetland, swamp forest, upland forest and open water.  The southern part of the marsh is at least 2,200 years old.

In the 18th and early 19th century, the marsh was called "Hell Hole  Swamp."  In the early 1800s, people built earthen walls around the perimeter of part of the marsh to create more "fast land," land not inundated by high tides. The "dyked" area was then used to graze livestock and to grow crops. The walls failed. 

From 1940 to 1972, Smoot Sand and Gravel dredged and hauled away almost half of the marsh, destabilizing the entire system.  See "The Accelerating Erosion of Dyke Marsh" and our restoration page.

Today, Dyke Marsh is one of the largest remaining, freshwater, tidal wetlands in the Washington metropolitan area, but the wetlands have diminished to under 50 acres.

Dyke Marsh is home to many species that can only survive in wetlands.  Wetlands are by their nature a water-laden environment with an enormous diversity of life forms.  Wetlands provide ecological services for free. For example, they mitigate flooding, buffer storms, filter pollutants and provide habitat.

Dyke Marsh is habitat for 300 known species of plants, 6,000 arthropods, 38 fish, 34 mammals, 16 reptiles, 14 amphibians, over 270 species of birds and at least 20,000 species of insects. 

Dyke Marsh, a Well-Studied Marsh

Under the sponsorship of the Friends of Dyke Marsh, ecologist and author David W. Johnston, Ph.D., (1926-2015) consolidated and summarized many studies and reports addressing Dyke Marsh and published a paper in the Virginia Journal of Science (Volume 51, Number 4, Winter 2000).   This compilation is an invaluable historical record and source of data about Dyke Marsh’s ecology, flora and fauna and human interaction.

The Virginia Journal of Science has made it available online here.  You can access it on our website at Johnston Study.  FODM has a limited number of reprints. Email us to determine availability and briefly explain your interest in the document.

Dr. Johnston was a member of FODM’s Board of Directors.  He served in the U.S. Navy, earned his Ph.D. from the University of California at Berkeley, taught ornithology and conducted research at Wake Forest University, the University of Virginia and the University of Florida.  He was Ecology Director at the National Science Foundation and worked at the National Academy of Sciences.  He published widely on ornithology and ecology.

Animals of the Marsh

Dyke Marsh supports a diversity of animals, including gray squirrels, cottontail rabbits, shrews, field mice, river otters, red fox, little brown bats and whitetail deer.  Evidence of beaver activity is often visible along the Haul Road and boardwalk. Beavers and muskrats can be seen swimming in the marsh in the early evening. Fish include carp, bullhead, chain pickerel, shad, striped bass and shiners. Reptiles such as snapping turtles and northern water snakes and amphibians such as frogs are also common. The table at right lists all the mammals observed in Dyke Marsh over more than 30 years as documented in the FODM sponsored study The Dyke Marsh Preserve Ecosystem by David W. Johnston.

Beaver Activity in Western Dyke Marsh

FODMer Laura Sebastianelli is monitoring beavers in the western part of Dyke Marsh, behind River Towers. On May 1, she spotted two families, two adults and a kit and two adults and two kits nursing. At one point, she saw five adults and three kits on top of the lodge (see photo) and at least one beaver swimming around. Thank you, Laura. This is a very special, little-visited part of Dyke Marsh.

FODMers Learn About Frogs and Bats

FODM member Deborah Hammer led a group of 35 on a frog and bat walk in the western part (photo, left) of the Dyke Marsh Wildlife Preserve on the evening of May 1.  Deborah is a bat educator and rehabilitator.  She lives nearby and has observed frogs and bats in this part of Dyke Marsh for the last 13 years.  She is concerned that she is not hearing many spring peepers or seeing as many bats as she used to.  “The sky used to be filled with them,” she commented.

     Deborah told the group that frogs and toads need still water like ephemeral pools upland to lay eggs and hatch tadpoles.  Bats need woodland trees upland of wetlands for nesting and marsh areas for hunting for food.  She is concerned that development proposed for Westgrove Park to the west of Dyke Marsh could destroy or degrade the little nearby suitable habitat that remains.  “It’s all interconnected,” she commented.

      She offered many interesting facts, among them these:

■  The most common native frogs here are the green frog, bullfrog, spring peeper and southern leopard frog.  Dyke Marsh is the southern leopard frog’s northernmost habitat.

■  Bats can live 20 years on average, are the only mammal that flies and can eat 3,000 insects a night.

■  There are 16 bat species in Virginia and 10 in Fairfax County. (Little brown bat, photo by Rick Reynolds.)

Birds

Least bittern (Ixobrychus exilis). Photo by Ed Eder.Scarlet tanager. (Piranga olivacea) Photo by Ed Eder.Birds are perhaps the most visible and accessible animal species of the marsh.  Bird-watching, or birding has made the Dyke Marsh Wildlife Preserve a popular attraction for many visitors.  There are resident species in every habitat from emergent wetlands to upland forests as well as migratory species that visit the marsh each spring and fall.  FODM has conducted several studies and surveys on birds and bird life and has documented over 270 species in Dyke Marsh. For a complete list including seasonal occurrence, see our Bird List page and see our Breeding Bird Survey page for a report on birds that breed in Dyke Marsh.  These studies help to monitor the overall health of the marsh by documenting trends in bird populations such as in The Marsh Wren – Loss of Habitat, Loss of Birds below. FODM also participates in the annual Christmas Bird Count and leads a weekly Sunday morning bird walk all year.

Intriguing Owls

Eastern screech owl (Megascops Asia). Photo by Ed Eder.

Barred owl. (Strix varia) Photo by Ed Eder.At least three species of owls have been observed in the Dyke Marsh Wildlife Preserve over the years – barred owl (Strix varia), Eastern screech owl (Megascops asio) and the great horned owl (Bubo virginianus).

FODM President Glenda Booth has written an article in the January-February 2019 Virginia Wildlife magazine, titled “Virginia’s Most Mysterious Birds.” You can read the entire article here.

Butterfly and Host Plant Checklist for Dyke Marsh

Eastern tiger swallowtail (Papilo glaucus). Photo by Glenda BoothMonarch butterfly (Danaus plexippus). Photo by Glenda BoothButterfly checklist - Friends of Dyke Marsh volunteers conduct butterfly surveys from April to October every year. Working with staffers from the National Park Service, George Washington Memorial Parkway unit, we have prepared a butterfly checklist for our members and visitors. The checklist includes butterflies you could observe in Dyke Marsh and many of their host plants. Thank you to the following for helping produce this brochure: Jessica Strother, Jim Waggener, Mark Maloy and Brent Steury.

You can read the checklist here.

FODM Poster in a 2020 National Park Service Research Event

FODM participated in the National Park Service’s (NPS) Spotlight on Resources research conference on October 7 and 8, 2020. Jessica Strother and Bob Veltkamp prepared a poster describing our almost five years of volunteer surveys of dragonflies, damselflies and butterflies in Dyke Marsh. The poster, which includes 11 photographs, documents the species surveyed from 2016 through 2019: butterflies, 49 species; damselflies, 12 species; dragonflies, 36 species. Click here to view the poster. Our thanks to the dedicated volunteers and to NPS for the opportunity to share our work.

The Butterflies, Dragonflies and Damselflies of the Dyke Marsh Wildlife Preserve, 2016 to 2020

Twelve-spotted skimmer (Libellula pulchella). Photo by Kevin MunroeRusset-tipped clubtail (Stylurus plagiatus). Photo by Kevin MunroeSince 2016, volunteers from FODM and the Audubon Society of Northern Virginia have conducted surveys of butterflies, dragonflies and damselflies in Dyke Marsh from April to October, led by Jim Waggener and Jessica Strother.

2020 marked the fifth consecutive year. Their volunteer efforts built on previous surveys by Dr. Ed Barrows, Georgetown University, and Christopher Hobson, Virginia Department of Conservation and Recreation, Division of Natural Heritage in 2016.

The surveyors covered a defined area around the Belle Haven Marina and the Haul Road trail, using the same methodology each year, except in 2020, volunteers followed covid-19 pandemic protocols for their protection.

2020 Results

In 15 surveys totaling 33 field hours, the volunteers documented 33 butterfly species and 19 dragonfly species. They added two butterfly species to the previous list: the American snout (Libytheana carinenta) and the great spangled fritillary (Speryeria cybele). They added three species to the dragonfly/damselfly list: the twelve-spotted skimmer (Libellula pulchella), the shadow darner (Aeshna umbrosa) and the swift river cruiser (Macromia illinoiensis illinoiensis) .

A few highlights:

• Butterfly species outnumbered dragonflies (51 to 39), but far more individual dragonflies and damselflies were counted than butterflies.
• The group found new species each year.
• The group observed a more positive trend in monarch butterflies than in the first year of the survey, 2016.
• Species and overall numbers of dragonflies continue to decline.

To read the report covering all five years of surveys, click here. To see the species checklist showing species identified over the five years, click here. To reach the FODM butterfly and host plant checklist, click here.

Eastern tiger swallowtail(Papilio glaucus), black form. Photo by Glenda BoothEditor’s note: FODM volunteers are working to control invasive plants and add more native plants, especially at the native plant site on the Haul Road trail. Insects and plants co-evolve and insects like butterflies depend on certain native or host plants for food and shelter. We assume that more aggressively controlling non-native plants like English ivy and porcelain berry could provide more support for native insects, like those that these surveys target.

The Friends of Dyke Marsh send athank you to the following volunteers: Jim Waggener, Jessica Strother, Ed Eder, Larry Cartwright, Margaret Fisher, Joel Goldman, Su Kim, Joan Haffey, Ken Larsen, Joanne and Powell Hutton, Larry Meade, Rusty Moran, Gary Myers, Dave Nichols, Kristi Odom, Fred Siskind and Dixie Sommers. Thanks too to Brent Steury, George Washington Memorial Parkway, Natural Resources Program Manager.

The Dragonflies and Damselflies of the Dyke Marsh Wildlife Preserve, 2011 to 2019

The autumn meadowhawk (Sympetrum vicinum ), our most cold-hardy dragonfly, perched near water on Haul Road. Photo by Ed EderFODM volunteers have conducted lepidoptera and odonata (butterflies, dragonflies and damselflies) surveys from April to October ever year since 2016. Here are the total species observed from 2016 to 2019: Butterflies - 49 species; Damselflies - 12 species; Dragonflies - 36 species.

Chris Hobson, with the Virginia Department of Conservation and Recreation, Division of Natural Heritage, conducted a four-day field survey, sponsored by FODM, in 2011 by boat and on foot between May and September.  Dr. Edd Barrows, a Georgetown University entomologist, has identified four additional species. 

Hobson identified the following 16 species in 2011:

Common Green Darner (Anax junius), Orange Bluet (Enallagma signatum), Big Bluet (Enallagma durum), Prince Baskettail(Epitheca princeps), Common Pondhawk (Erythemis simplicicollis), Eastern Forktail (Ischnura verticalis), Fragile Forktail (Ischnura posita), Slaty Skimmer (Libellula incesta), Needham’s Skimmer (Libellula needhami), Great Blue Skimmer (Libellula vibrans), Wandering Glider (Pantala flavescens), Blue Dasher (Pachydiplax longipennis), Eastern Amberwing (Perithemis tenera), Common Whitetail (Plathymis lydia), Russet-tipped Clubtail (Stylurus plagiatus), Black Saddlebags (Tramea lacerate).

 On July 22, 2013, Hobson added four more species to the survey:

Widow Skimmer (Libellula luctuosa), Twelve-spot Skimmer (Libellula pulchella), Halloween Pennant (Celithemis eponina), River Cruiser (Macromia sp.).

Male eastern amberwing (Perithemis tenera) perched on marsh vegetation. Photo by Christopher S. HobsonAny survey is a “snapshot” at a given time and place, not a comprehensive inventory.  Total numbers seen on any day can vary tremendously, depending on the weather and time of year.  Hobson saw more than 1,000 of one species in one day and hundreds of another during a short paddling trip, for example.  His report notes that “there seems to be a core group of species that can be found consistently in and around the marsh” and that a number of other resident and migratory species could occur in the marsh.

Big bluet (Enallagma durum) mated pair showing sexual dimorphism in both color and pattern. Photo by Christopher S. HobsonDragonflies and damselflies are in the order Odonata.  These insects have two pairs of wings and three pairs of legs, among other characteristics.  Dragonflies typically spread their wings to their sides when they land and are typically larger and more robust.  Damselflies are usually smaller and they typically hold their wings together over their abdomen.  Their eyes are separated.  To identify specific species, experts study their wings, wing patterns, colors, tail, thorax, abdomen, genitalia and other features, some under a microscope.  Some have bright, lustrous hues and diaphanous wings.  Behavior is another important factor in identification of Odonata. 

Dragonflies and damselflies are found around rivers, wetlands, seeps, bogs, springs, streams, ponds and lakes because their larvae, known as nymphs, are aquatic.  Adults can be from half an inch to five inches long.  Some species migrate south and return to Virginia in the spring. In Virginia, at least 194 species of dragonflies and damselflies have been identified.  The best time to see them is from April to October.

Hobson submitted a report to FODM and to the National Park Service.

Plants of the Marsh

Narrowleaf Cattail
(Typha angustifolia L.)The dominant species of plant is the narrowleaf cattail, a plant more common to salty water.  This plant typically develops its characteristic flower spike by June and releases seeds in the fall. Other species include arrowhead, arrow arum, pickerelweed, sweetflag, spatterdock and wild rice.

Unfortunately, many non-native plant species have been introduced into the area, plants that often outcompete beneficial native species.  Examples are porcelainberry, Japanese honeysuckle, multi-flora rose and Asian bittersweet. 

Saturday Morning Plant Walk in Dyke Marsh

On a hazy Saturday morning on July 26, 2014, about 30 FODM members and friends turned out for a plant walk led by Dr. Elizabeth Wells (“Call me Beth”), Associate Professor Emerita of Botany at The George Washington University. Dr. Wells’s walks are always engaging and informative, and this one was no exception: the enthusiastic group observed a number of colorful and interesting plants. FODM President Glenda Booth provided the accompanying photos with essay by Pat Salamone. 

The tropical-looking blossoms of the swamp rose mallow (Hibiscus moscheutos) are among the largest flowers produced by any perennial that is winter-hardy in our area.     Dyke Marsh is home to two plants known as swamp dogwood, Cornus amomum and Cornus foemina, which are very similar in appearance. The blue berries of the swamp dogwood are eaten by several species of birds.

The native wild grape vine (Vitus L.) bears drooping clusters of fruit in the familiar bunch-of-grapes form.

   Swamp milkweed (Asclepias incarnata) serves as a host plant for monarch butterfly caterpillars.  

Smooth sumac (Rhus glabra) has compound pinnate (feather-like) leaves
that turn red and orange in the fall, and bears clusters of small round red
fruits that serve as winter food for wildlife.
   The purple flower spikes of pickerelweed (Pontederia cordata) are pollinator magnets.

The tubers of the groundnut vine (Apios americana) were an important food source for many Native American tribes and some early European colonists. The vine bears clusters of beautiful reddish purple sweet-pea-like flowers.
    Although a member of the carrot family (Apiacieae) and looks similar to Queen Anne’s Lace, water hemlock (Cicuta maculata) is highly poisonous.

The tall coneflower or cutleaf coneflower (Rudbeckia laciniata) is recognized by pollination ecologists as attracting large numbers of native bees, according to The Xerces Society for Invertebrate Conservation.

Trying to Save Pumpkin Ash Trees

Robert Smith from FODM and Brent Steury from NPS were members of the project team that identified trees for treatment. Photo: G. Booth                FODM is partnering with the National Park Service (NPS) on a project to try to save some of the preserve's pumpkin ash trees (Fraxinus profunda) from destruction by the emerald ash borer (EAB) (Agrilus planipennis), an invasive insect that was found in Fairfax County in 2003 and has been documented in Great Falls and Turkey Run Parks.  "An EAB infestation is always fatal to ash trees," says the U.S. Department of Agriculture (USDA) website.  The insect could kill all of the pumpkin ash trees in Dyke Marsh in 20 years without action. 

                Dyke Marsh has over 1,000  pumpkin ash trees.  These trees thrive in wet areas like swamps, floodplains and bottom lands, can reach 130 feet in height and have a 68-inch diameter.   The pumpkin name comes from the trees' usually swollen or pumpkin-shaped butt or base.  

Ensuring a Breeding Stock

Lizardo Bonilla-Teza of Bartlett Tree Experts treated four trees on May 16, 2016. Photo by Robert Smith                FODM's goal is to help NPS maintain a small, healthy breeding stock of these trees.  In the spring of 2015, we contracted with Bartlett Tree Experts to conduct an insecticide treatment called Tree-age into the root flares of nine selected trees (Joshua Darkow applies treatment, photo left) in hopes that the treatment will kill any emerald ash borers infesting the trees.  NPS chose a small group of trees located close together because ash trees have both male and female flowers and are air pollinated.   NPS also tagged and wrapped the trees with beaver-resistant netting.  Bartlett's Joshua Darkow injected the trees on May 13.  If the treated trees remain healthy for two years, we hope to repeat treatments until the EAB infestation has passed through our area. There is no guarantee that the treatment will be successful.

Four staffers from the North Carolina Botanic Garden helped NPS and FODM collect pumpkin ash seeds in September. Credit: Robert Smith                In September, four North Carolina Botanic Garden staff members, with the assistance of Peter McCallum and Brent Steury from NPS and Robert Smith from FODM, collected pumpkin ash seeds in Dyke Marsh for preservation. They met their goal of 10,000 or more seeds from 25 or more trees. These seeds will be available in the future to help in the marsh's restoration and to replace trees expected to be lost to the EAB. 

               On May 16, 2016, with support from FODM and NPS, Bartlett Tree Experts treated another four pumpkin ash trees for the emerald ash borer. At that time, there were many dead trees, presumably because of this non-native insect. “Significant numbers of ash trees along the George Washington Memorial Parkway and in Dyke Marsh have failed to leaf out this spring,” said FODM project manager Robert Smith, “presumably due to the emerald ash borer. However, the nine trees we treated last spring are all in good shape.” He added, “Adding these trees to the initial group will greatly enhance the chances that we will be able to maintain a healthy set of pumpkin ash trees in the marsh. Hopefully, they will be able to both propagate themselves and provide seeds for use in the restoration.”

              FODMers observed seeds on many treated trees in September 2017. Referring to the trees treated in 2015, NPS Biologist Brent Steury said,” The first nine trees were obviously much healthier than any other ash trees in the area except the four I selected for treatment in this round.”

               “Most of the surrounding ash trees are dead with one notable exception and that is a female at the far southeastern edge of the copse that also produced plenty of seeds.  Of the study trees, three showed some significant bare areas ranging from approximately 25 percent to 40 percent of the branch area, but this does not indicate a fatal emerald ash borer infestation.  Two of these trees were added in 2017 and showed some bare areas at the time of treatment but were determined worth trying to save.”

               On September 25, 2017, five FODMers and Brent Steury with the National Park Service surveyed the treated trees in Dyke Marsh.  Project leader Robert Smith wrote, “It was very encouraging to see that all of these trees had leafed out this season and that all six of the females had produced plenty of seeds.  Six of the trees were originally treated in 2015, four more were treated in 2016 thanks to a dedicated donation, and six more were added by NPS in 2017 and all 16 were treated this spring with NPS funding (mitigation for three that were accidentally removed last year).

               On April 11, 2019, FODM and National Park Service (NPS) employees revisited the pumpkin ash preservation site.   FODM will finance the treatment of two more trees in May 2019. 

               In preparation for the treatment, Brent Steury, NPS Natural Resources Manager, Stephen Fagin, NPS Horticulturist, and Robert Smith, FODM Project Manager, surveyed the 16 study trees. They also wrapped trees with wire mesh to prevent beavers from chewing them down and tagged two trees for probable addition to this year’s treatment program.  They took diameter measurements, put fresh orange ribbons on the study trees and did some minor clearing of invasive plants. 

               The success of this project is unknown. The emerald ash borer usually kills the trees it infects.  It is too early in the year and in the study to draw any firm conclusions about the treatment’s effect or the health of the trees.

       "It is painful to imagine Dyke Marsh without its expanse of ash trees so we are doing what we can to ensure that they will revive after an attack," said Robert Smith, FODM project manager. Photos courtesy of Glenda Booth.

Destabilizing an Unstable Marsh

                Dead trees and fewer trees in the marsh would further  destabilize Dyke Marsh, NPS officials maintain.  Dyke Marsh is already eroding 1.5 to two acres a year and will be gone in 20 years without action, concluded the U.S. Geological Survey in a 2010 study.  Dredging of the marsh from 1940 to 1972 destabilized the marsh.  USGS concluded that Dyke Marsh "has shifted from a semi-stable net depositional environment (1864-1937) into a strongly erosional one . . .  The marsh has been deconstructed over the past 70 years by a combination of manmade and natural causes."             

The Metallic Green Invader

This dead log, which washed up on the shoreline in Dyke Marsh, shows how the emerald ash borer bores "tunnels" in trees and ultimately kills the tree. Credit: Glenda BoothClose-up of emerald ash borer tunnels. Credit: Glenda Booth      EAB is a metallic green, wood-boring beetle from Asia, one-half inch long and one-eighth inch wide.  Experts believe it probably came to the U.S. in wood packaging material. 

      From May to August, adult EABs emerge from winter hibernation and mate. EAB females can lay up to 200 eggs in the beetle's lifetime.  They deposit the eggs in bark crevices or under bark flaps. After the eggs hatch, larvae chew through the bark and tunnel into the phloem and cambial region of the tree. The wormlike larvae feed on the inner bark and disrupt the tree's ability to transport water and nutrients.  They create squiggly, serpentine patterns called "galleries." In late spring, adults emerge through a four millimeter, D-shaped hole.  The D-shaped hole is a telltale sign of the EAB.

Devastation

                All species of ash are at risk, reports USDA, as what's been called "the green menace" creeps across the land.  Tens of millions of trees have already died or are heavily infested in the U.S. and Canada.  A tree's decline is gradual.  A USDA map  https://www.aphis.usda.gov/plant_health/plant_pest_info/emerald_ash_b/downloads/AshRangeMap.pdf) shows the insect's presence in most states east of the Mississippi River.

                EAB infestations are difficult to detect.  Woodpeckers feeding on dead branches near the tree's top could be a sign of an infestation.  Woodpeckers are natural predators, but unfortunately, they have not prevented many trees from dying or slowed the pest's spread.

                Virginia is under a federal EAB quarantine which prohibits the interstate movement of certain articles including ash logs, ash nursery stock , lumber, firewood and any other ash material, living, dead, cut or fallen, including logs, stumps, branches, roots and composted and uncomposted chips from any species of ash.

                For more information, visit www.emeraldashborer.info/, http://www.mountvernongazette.com/news/2020/oct/31/baseball-bats-and-ash-trees-face-uncertain-fate/ and www.vainvasivespecies.org/species/emerald-ash-borer

The Marsh Wren -- Loss of Habitat, Loss of Birds

by Glenda C. Booth

Marsh Wren (Cistothorus palustrus)
Photo by Ed EderIt’s a little brown bird that lives in marsh cattails, bulrushes or cordgrass, and known for its calls. Some people hear a rusty hinge. Others say it’s a sputtering, bubbling trill. Other fans liken the call to a clattering sewing machine, a guttural rattle or a liquid gurgle, ending in chatter. It can be a loud little bird, especially on a spring night.

It is the marsh wren (Cistothorus palustris), once a common bird in the Dyke Marsh Wildlife Preserve. The Dyke Marsh Wildlife Preserve today supports the only known nesting population of marsh wrens in the upper Potomac River tidal zone.

National Park Service biologist Brent Steury wrote, “Marsh wrens are cute little brown-eyed birds not much over five inches long and weigh in at about half an ounce. Their dark brown cap rests atop a bold white supercilium, or eyebrow, that broadens as it extends from the base of the bill to the base of the neck. The body is chestnut, with a black, white streaked cape over the shoulders. The throat is nearly white and the belly pale buff. Sexes are identical. Active and noisy, they flutter rapidly among the cattails, often observed when perched with splayed legs, each foot tightly clasping a separate stem, bill agape in loud unmistakable song.” They usually hold their tails upright or often almost laying on the back, a distinctive trait.

Marsh wrens breed in fresh and brackish marshes, usually in areas of dense, reedy vegetation. They construct elaborate football-shaped nests with round openings by weaving grasses or cattail leaves in a circular manner anchored to reeds or cattails a few feet above the water. The male builds several “dummy nests” nearby, presumably to trick predators.

Seeing a marsh wren can be challenging, except during the breeding season, when males perform aerial displays before alighting on singing perches on the perimeters of their claimed breeding territories or when building one of their dummy nests. They often flit around furtively, popping up now and then to look around.

A Steady, Sad Decline

The Dyke Marsh Wildlife Preserve was once popping with marsh wrens. In the late 1800s, observers reported of hundreds of globular marsh wren nests affixed to reeds in the wetlands that lined the Potomac River, wetlands now largely gone.

Louis Halle, who biked from Washington, D.C., to Dyke Marsh, extolled this little bird in his 1947 Spring in Washington: “We heard the wrens this morning before there was light to see them. All over the marshes we heard them, singing in a steady chorus, each song a gurgling chatter, brief but repeated with hardly time for breath between. When it became light enough, we saw the singing wrens as far as the eye could reach over the marshes, carried upward on fluttering wings above the grass-tops by the very exuberance of their song, and sinking back again. The dots were bobbing up and down everywhere, like a natural effervescence given off by the marsh.”

In 1950, surveyors counted 87 singing males in Dyke Marsh. "Thirty-one territories were located in 1998 and 34 in 1999. The minimum estimated population size for 1998 was 38 (34 territorial males and seven breeding females); and for 1999, 48 (34 territories males and 14 breeding females)," wrote Sandy C. Spencer in her 2000 master’s degree thesis for George Mason University. (Spencer is now Supervisory Wildlife Biologist at the Patuxent Research Refuge.)

In 2007, surveyors found six established territories; in 2008, 10 breeding pairs; in 2010 and 2011, 12 established territories, but in these years, surveyors probably did not cover the same areas. In the 2012 survey, Larry Cartwright, head of FODM’s annual breeding bird survey, confirmed only two active nests and reported that surveyors saw or heard eight territorial males and possibly two to four more, conservative estimates he believes. Surveyors have not confirmed any breeding marsh wrens since 2014, a very troubling trend.

“The fate of marsh wrens and least bitterns remain in doubt at Dyke Marsh, but the trend suggests eventual disappearance for at least the marsh wren,” Cartwright contends.

As Dyke Marsh erodes away, a major factor in the marsh wren’s decline is loss of habitat. Spencer offered this guidance in 2000: “Available habitat comprises only 12 percent of the entire preserve, but actual use by marsh wrens for nesting territories was only 3.6 percent in 1999, because of very narrow habitat selection preferences (tall, dense, emergent vegetation adjacent to water). Protection of the remaining habitat from reduction or degradation due to expansion of invasive plants and erosion and restoration of lost habitat are strongly recommended to ensure persistence of this population over the long term.”

Breeding Bird Survey

The Results of the 2020 Dyke Marsh Breeding Bird Survey

By Larry Cartwright, Breeding Bird Survey Coordinator                                   

Volunteers conducted the 2020 Dyke Marsh Breeding Bird Survey from May 23 to July 4, 2020. Any data collected outside of this period that confirmed breeding activity was entered into the database. This permitted us to filter out most migrants that do not breed in Dyke Marsh. I also included information provided from reliable individuals to supplement data reported by the survey teams. The FODM Sunday morning bird walks provided no additional data since FODM had to cancel them in early 2020 because of the COVID-19 virus. 

The survey tract encompassed the Belle Haven picnic area, the Belle Haven marina, the open marsh, that portion of the Big Gut known as west Dyke Marsh that extends under the George Washington Memorial Parkway west to behind the River Towers Condominiums, the Potomac River from the shoreline extending to the channel of the river and the adjacent woodland and open area south of Hunting Creek to south of Morningside Lane.  

Methodology

The survey methodology uses behavioral criteria to determine the breeding status of all species found in the survey tract.  Species are placed into one of four categories: 

• confirmed breeder, 
• probable breeder, 
• possible breeder and 
• present

Despite the difficulties in conducting the survey under restrictive COVID-19 pandemic protocols, our teams did quite well. We found 75 species at Dyke Marsh during 2020. We confirmed 46 species as breeders, seven as probable breeders, and 13 as possible breeders. We listed an additional nine species as present. They were a combination of colonial breeding waterbird species not using a rookery inside the survey tract, species in unsuitable breeding habitat and migrants still headed north.

Prothonotary Warblers, a Highlight

Adult prothonotary warbler (Protonotaria citrea) shown feeding fledged youngster. Photo by Ed Ed

The prothonotary warblers’ (Protonotaria citrea) impressive breeding success was a highlight of the 2020 survey. When I became compiler of the breeding bird survey in 1994, volunteers usually found prothonotary warblers from the Big Gut bridge  across from Tulane Drive south to below Morningside Lane. The birds sometimes used nest cavities in short snags right along the shoreline of the Big Gut or Potomac River, making confirmation of breeding rather easy. Finding other nests away from the immediate shoreline was impossible, but eventually a lucky volunteer would spot an adult carrying food or feeding fledged young.

Over a decade ago, perhaps one or two prothonotary warblers began occupying territory along the Haul Road trail and on Coconut Island, probably because the presence of standing water and the availability of snags made the habitat increasingly appealing to the birds. In 2020, surveyors reported prothonotary warblers at the Belle Haven marina, the Haul Road trail entrance, near the Haul Road trail overlook that we unofficially call Dead Beaver Beach and beyond the dogleg turn in the Haul Road trail, perhaps representing four or more territorial males.  

Prothonotary warblers established as many as 10 additional territories in the south marsh. The first confirmation of breeding came from north of Morningside Lane on June 5 where a male was transporting a mouthful of food to nestlings. On July 11, a prothonotary warbler was feeding two fledged young at the Big Gut bridge, followed by an adult feeding two young north of the Haul Road trail dogleg on July 26 and a fledged youngster with a parent at the Haul Road trail entrance on August 10. Quite impressive.

Mourning Doves 

	Mourning Dove (Zenaida macroura)  sits on nest with nestling visible quite early in the breeding season. Photo by Laura Sebastianelli
	A blue-gray gnatcatcher (Polioptila crinitus) sits on  lichen-adorned nest on the Haul Road. Photo by Ed Eder

The mourning doves’ (Zenaida macroura) breeding season was equally impressive, even for this prolific species. These birds start the breeding season early in the spring and continue into late summer. 2020 was no different. However, we found a mourning dove breeding pair that may hold a Dyke Marsh record for producing the earliest fledged youngsters. On March 27, a mourning dove was sitting on a nest with two young. On April 3, the two now well-developed young were still in the nest but fledged by the following morning. If  you consider a short egg-laying period followed by a 14-day incubation and a 15-day nestling period, nest construction would have had to have commenced in late February. Now that is typical in the southern U.S., but not in northern Virginia as far as I know. Will wonders never cease? 

Most of the expected songbird species that occupy the wooded areas near marsh habitat during the breeding season were present in 2020. Among them were yellow warblers (Setophaga petechia)  and song sparrows (Melospiza melodia), both of which were absent in 2019 but occupied territory in 2020 and were confirmed as breeders. Baltimore orioles (Icterus galbula) were present in 2019, but survey teams were unable to find evidence of breeding. In 2020, we discovered a Baltimore oriole nest at the Haul Road trail dogleg.  

Some of the other more notable confirmed breeders documented during the 2020 survey include great crested flycatchers (Myiarchus crinitus), eastern kingbirds (Tyrannus tyrannus), warbling (Vireo gilvus) and red-eyed vireos (Vireo olivaceus), the extremely prolific blue-gray gnatcatchers (Polioptila caerulea), orchard orioles (Icterus spurius) and common yellowthroats (Geothlypis trichas). Remaining conspicuously missing in 2020 was the northern parula (Setophaga americana), which has not been recorded as a breeder or even occupying territory since 2017.  

Marsh Wrens,  Least Bitterns 

We conducted fewer canoe surveys in 2020 than in normal years because of COVID-19 concerns, but we were able to gather some data on the status of marsh wrens (Cistothorus palustris) and least bitterns (Ixobrychus exilis) from several of our outings. A June 19 survey revealed the presence of at least two probable territorial marsh wrens in the northeast passage in what we have termed the “northeast passage” as an unofficial location reference, a tributary of the upper Big Gut. By August 5, one of the birds had constructed three nests, but there was no evidence that any had been accepted and occupied by a female. Only one female-occupied nest has been reported since 2014, and the prospects for the marsh wrens’ recovery at Dyke Marsh currently seems bleak.

A least bittern (Ixobrychus exilis) peers out though the marsh vegetation. Photo by Ed Eder

Surveys of the Big Gut found most least bitterns occupying the northeast passage, with a high count of four recorded on June 12. The presence of a female on July 14 raised some hopes for breeding confirmation, but we were to be disappointed. In the north marsh, a few least bitterns occupied the tributaries of the Little Gut, but we found no evidence of breeding at that location either. Indeed, least bitterns have not been confirmed as breeders for five years, which only adds to the concern for the future of this species at Dyke Marsh. 

Raptors

	A recently fledged barred owl (Strix varia) on the right perched near one of its parents. Photo by Ed Eder

A highlight of raptors’ breeding was early April reports of a barred owl (Strixvaria) family group consisting of a breeding pair and two recently fledged young near the Haul Road trail entrance. We were aware of an adult presence through several sightings beginning in early March, but the debut of the youngsters on April 3 thrilled the birders and nature lovers who happened to be there to see them. The birds were celebrities for a few days before they began to recede into the thicker vegetation and became harder to spot. The youngsters reportedly were active and healthy as of June 22, the last day they were reported.   

A red-shouldered hawk (Buteo lineatus) pair made a nesting attempt near the River Towers condominiums in 2020. We identified a fledged youngster in the same area the previous year, but this was the first time that the survey ever recorded a red-shouldered hawk nest. Nest construction occurred in March. An April 27 outing documented the presence of a fluffy white young. Our delight was short-lived as the youngster perished soon after May 5, the last day the nest was observed to be occupied.  

The bald eagle (Haliaeetus leucocephalus) nest along the Haul Road trail, in its third active season, was popular among nature photographers and others despite the pandemic. The breeding pair did not disappoint. Observers documented two young by mid-March and for the next two and a half months, the developing nestlings provided entertainment for many visitors. The birds fledged on June 3. The Tulane Drive nest produced at least two young based upon an observation of a family group near the nest site in July, but the Morningside Lane nest apparently failed as volunteers never saw young and were unable to find adults at the nest site after May 11.   

Ospreys (Pandion haliaetus) did not have a banner year at Dyke Marsh. The birds constructed 10 nests, all of which could be monitored easily from land with a scope. One nest built on a crane on a barge in the channel was abandoned, or perhaps removed, by June 1. Of the remining nine nests, only three produced young. The nest residing on the platform beside the marina boat ramp fledged a single young osprey in early August, a month later than the normal fledging date around Independence Day. This may be attributed to the fact that the birds delayed construction for more than a week after they were first spotted at Dyke Marsh on March 10. The other two successful nests, each producing multiple nestlings, were at Porto Vecchio condominiums just north of Dyke Marsh and they also seemed to have started nesting later than normal. The fledging date for the young occupying the two Porto Vecchio nests was on or around July 21.    

I have been compiler of the Dyke Marsh Breeding Bird Survey since 1994 and have witnessed many changes in the breeding status and density of several avian species at Dyke Marsh since then. The decline of the marsh wren and least bittern, the return of the bald eagle and the ups and downs of several songbirds like prothonotary and yellow warblers are a few examples. These events have all been recorded by volunteers of the Friends of Dyke Marsh.  

Volunteers are valuable to continuing this survey and I would like to acknowledge those who participated in 2020. In alphabetical order, they are as follows: Dave Arnold, Eldon Boes, Glenda Booth, Jessica Bowser, John Cushing, Ed Eder, Deborah Hammer, Nathan Harms, Todd Kiraly, Joan Mashburn, Nick Nichols, Roger Miller, Mary Parrish, Rich Rieger,Laura Sebastianelli, Robert Smith, Dixie Sommers and Sherman Suter.

The 2020 Breeding Bird Survey Results:

Confirmed - 46 Species: Canada Goose, Wood Duck, Mallard, Mourning Dove, Osprey, Bald Eagle, Red-shouldered Hawk, Barred Owl, Red-bellied Woodpecker, Downy Woodpecker, Hairy Woodpecker, Northern Flicker, Pileated Woodpecker, Great Crested Flycatcher, Eastern Kingbird, Warbling Vireo, Red-eyed Vireo, Blue Jay, Fish Crow, Tree Swallow, N. Rough-winged Swallow, Barn Swallow, Carolina Chickadee, Tufted Titmouse, White-breasted Nuthatch, House Wren, Carolina Wren, Blue-gray Gnatcatcher, American Robin, Gray Catbird, Northern Mockingbird, European Starling, Cedar Waxwing, House Sparrow, House Finch, American Goldfinch, Song Sparrow, Orchard Oriole, Baltimore Oriole, Red-winged Blackbird, Brown-headed Cowbird, Common Grackle, Prothontary Warbler, Common Yellowthroat, Yellow Warbler, Northern Cardinal.

Probable - 7 Species: Yellow-billed Cuckoo, Eastern Wood-Pewee, Willow Flycatcher, Purple Martin, Marsh Wren, American Redstart, Indigo Bunting.

Possible - 13 Species: Hooded Merganser, Wild Turkey, Chimney Swift, Ruby-throated Hummingbird, Least Bittern, Green Heron, Belted Kingfisher, Acadian Flycatcher, Eastern Phoebe, American Crow, Brown Thrasher, Northern Parula, Scarlet Tanager.

Present - 9 Species: Rock Pigeon, Whimbrel, Ringbilled Gull, Double-crested Cormorant, Great Blue Heron, Black Vulture, Alder Flycatcher, Bobolink, Blackpoll Warbler.

Definition of Categories:

Confirmed Breeder: Any species for which there is at minimum evidence of a nest. A species need not successfully fledge young to be placed in the confirmed category.

Probable Breeder: Any species engaged in pre-nesting activity, such as a male on territory, courtship behavior, or even the presence of a pair, but for which there is no evidence of a nest. Since birds can and do sing and display to females during migration, this category cannot be used until the safe dates are reached. 

Possible Breeder: Any species, male or female, observed in suitable habitat, but giving no hard evidence of breeding. Unless actively breeding, all birds in suitable habitat before the start of the safe date are placed in this category.

Present: Any species observed that is not in suitable habitat or out of its breeding range. It also applies to colonial water birds in the survey tract not associated with a rookery in the tract.  

Definition of Safe Dates

We use safe dates as a means of deciding if a bird can be considered a breeder or a migrant. Safe dates are simply defined as a period beginning when all members of a given species have ceased to migrate in the spring and ending when they begin to migrate in the fall. Unless a bird is engaged in behavior that confirms breeding, it will be placed no higher than in the possible breeder category if it is observed outside the safe dates assigned to that species. 

The Results of the 2019 Dyke Marsh Breeding Bird Survey

By Larry Cartwright, Breeding Bird Survey Coordinator

Larry Cartwright Marks 20 Years at Breeding Bird Survey

The Friends of Dyke Marsh honored Larry Cartwright at the quarterly meeting on May 16, 2012, with a certificate of appreciation for organizing and leading the survey for 20 years. This activity, a continuing biological inventory of the birds of the Dyke Marsh Wildlife Preserve, has provided trend information since the 1960s. The Friends also gave Larry a portrait a prothonotary warbler, Larry's favorite bird. FODM President Glenda Booth presided.

Volunteers conducted the 2019 Dyke Marsh Breeding Bird Survey between May 25 and  July 4, but any data collected outside of this period that confirmed a breeding species was entered into the database. This permitted us to filter out most migrants that do not use the marsh or surrounding habitat to breed. I also included information provided from the Sunday morning walks and reliable individuals to supplement data reported by the survey teams. The survey tract encompasses the Belle Haven picnic area, the marina, the open marsh, that portion of the Big Gut known as West Dyke Marsh that extends from the George Washington Memorial Parkway west to River Towers, the Potomac River from the shoreline to the channel, and the surrounding woodland from the mouth of Hunting Creek to south of Morningside Lane.

The breeding bird survey methodology uses behavioral criteria to determine the breeding status of each species found in the survey tract. Species are placed into one of four categories: confirmed breeder, probable breeder, possible breeder, and present. We identified 71 species at Dyke Marsh during 2019. There were 40 confirmed breeding species, 10 probable breeders, and 13 possible breeders. An additional 8 species were listed as present, but either were colonial breeding waterbird species not using a rookery inside the survey tract, species in unsuitable habitat for breeding, or migrants still transiting northern Virginia to breeding areas further north.

Adult pileated woodpecker (Dryocopus pileatus) feeding fledged young. Photo by Ed EderThe 2019 survey revealed some noticeable changes in songbird presence and distribution. Some species like great crested flycatcher (Myiarchus crinitus), eastern kingbird (Tyrannus tyrannus), and orchard oriole (Icterus spurius) were found in their usual abundance and all bred at Dyke Marsh Wildlife Preserve. However, for the first time since I became compiler in 1994, yellow warblers (Setophaga petechia) and Baltimore orioles (Icterus galbula) were not confirmed as breeders. Although volunteers discovered four or five territorial Baltimore oriole males and even a male-female pair, we found no evidence of breeding. Yellow warbler males did not even attempt to establish territory. Song sparrows (Melospiza melodia), often confirmed as breeders in past years, were also absent.

Warbling vireos (Vireo gilvus) were confirmed as breeders in 2019 and although numbers were robust around Haul Road and the Belle Haven picnic area, the density in the south marsh was dramatically diminished. Although we could easily find up to nine warbling vireos in the picnic area and Haul Road during a morning outing, it was extremely difficult to document more than two singing males while conducting a survey from the Big Gut Bridge and Tulane Drive south to Morningside Lane.

The results of the 2019 survey also indicated a drop in the number of songbird young that fledged, including the more common species like eastern kingbird and orchard oriole, where we found numerous nests of both species, but fewer than expected family groups. We found no warbling vireo nests or fledged young in 2019. Our confirmation of this species consisted of an adult carrying food to an unlocated nest.

Northern flickers (Colaptes auratus) copulating. Photo by Ed EderThere are several possibilities as to what happened during the 2019 breeding season. We have discussed the possible effect of unsettled weather and a warming climate, a reported drop in the insect and other arthropod prey base, the death of numerous pumpkin ash trees and the likelihood that 2019 was just an off year. It may be a combination of events occurring simultaneously. The death of pumpkin ash trees has opened many areas that used to produce canopy cover that may have concealed many songbird nests from predators. I received one report in 2019 of fish crows attacking and consuming eastern kingbird nestlings along the boardwalk at the end of Haul Road. Perhaps predation is becoming a more frequent event.

Volunteer surveyors always play close attention to two prominent birds that occupy the open marsh, the marsh wren (Cistothorus palustris) and the least bittern (Ixobrychus exilis). We have found only one active marsh wren nest since 2014. Despite the lack of breeding attempts, at least a few marsh wren males occupied the marsh, even if only briefly, since 2015. The 2019 survey recorded no marsh wrens at Dyke Marsh, the first time this has happened in my tenure as compiler.

The status of the least bittern seems more precarious than ever. One caveat is that we conducted only two canoe routes in the south marsh in 2019, but canoe teams covered the marsh around the Haul Road, Little Gut, and the western edge of the marsh south of the Little Gut to Bird Island almost weekly. These canoe teams plus a land-based team yielded only two reports in early June of a least bittern in one of the tributaries of the Little Gut. The two southern canoe teams conducted their surveys in late June. Each of these teams reported one bird, both in the upper portion of the Big Gut, but at separate locations. That is the total sum of least bittern reports for 2019.

Bald eagle (Haliaeetus leucocephalus) nest on Haul Road with one adult and one of two nestlings. Photo by Ed EderThe Haul Road nesting bald eagles (Haliaeetus leucocephalus) were successful in the second season of this nest's existence. The novice breeding pair fledged one young bird in 2018; this year they doubled that effort with two youngsters fledging by early June. The Morningside Lane breeding pair produced at least one fledged young, but we found no fledged birds that could be associated with the Tulane Drive nest.

Ospreys (Pandion haliaetus) built eleven nests in 2019. A nest on Bird Island was destroyed by Memorial Day weekend apparently when part of the tree supporting it broke off and a second nest built on a huge stump in the Potomac River near Porto Vecchio met a similar fate when it was washed away. Of the remaining nine nests, only half produced nestlings and fledged young. Successful nests tended to be closer to or along the shoreline while unsuccessful nests were further out in the river on pilings or other artificial structures. I have no ready explanation or theory as to why this would be the case. I initially toyed with the idea that something may have impacted the fish prey base in the open river, but there is no tangible evidence to prove that.

Finally, and much to my surprise, we added four first-time confirmed breeders to the Dyke Marsh list, consisting of one waterfowl species, two hawks, and a songbird. In April, one of our volunteers who resides at River Towers, spotted a hooded merganser (Lophodytes cucullatus) hen with eight recently hatched young in West Dyke Marsh. The actions of a red-shouldered hawk (Buteo lineatus) pair courting and copulating in West Dyke Marsh throughout March culminated in the fledging of at least one youngster in July. Eastern bluebirds (Sialia sialus) bred in a cavity in an open park-like wooded area adjacent to the marsh in West Dyke Marsh. We observed a fledged youngster by late June. Finally, although the effort was abandoned, a nest building Cooper’s hawk (Accipiter cooperii) was documented along Haul Road in mid-April.

The Dyke Marsh Wildlife Preserve Breeding Bird Survey would not be possible without the dedication of those citizen-scientists who collected valuable data. The Friends of Dyke Marsh and I as the compiler are pleased to acknowledge all the people who contributed time and expertise to the survey in 2019. In alphabetical order, they are: Eldon Boes, Ed Eder, Sandy Farkas, Gerry Hawkins, Clark Herbert, Ellen Kabat, Elizabeth Ketz-Robinson, Dorothy McManus, Ginny McNair, Larry Meade, Roger Miller, Nick Nichols, Rich Rieger, Don Robinson, Laura Sebastianelli, Phil Silas, Robert Smith, Dixie Sommers, Sherman Suter, Margaret Wohler, Katherine Wychulis.

The 2019 Breeding Bird Survey Results:

Confirmed - 40 Species: Canada Goose, Wood Duck, Mallard, Hooded Merganser, Mourning Dove, Osprey, Cooper's Hawk, Bald Eagle, Re-shouldered Hawk, Red-bellied Woodpecker, Downy Woodpecker, Northern Flicker, Pileated Woodpecker, Eastern Phoebe, Great Crested Flycatcher, Eastern Kingbird, Warbling Vireo, Blue Jay, Fish Crow, Tree Swallow, Northern Rough-winged Swallow, Barn Swallow, Carolina Chickadee, Tufted Titmouse, House Wren, Carolina Wren, Blue-gray Gnatcatcher, Eastern Bluebird, American Robin, Gray Catbird, Brown Thrasher, Northern Mockingbird, European Starling, Cedar Waxwing, House Sparrow, House Finch, Orchard Oriole, Red-winged Blackbird, Common Grackle, Northern Cardinal.

Probable - 10 Species: Green Heron, Barred Owl, Eastern Wood-Pewee, Acadian Flycatcher, Red-eyed Vireo, American Goldfinch, Baltimore Oriole, Prothonotary Warbler, Common Yellowthroat, Indigo Bunting.

Possible - 13 Species:  Chimney Swift, Ruby-throated Hummingbird, Spotted Sandpiper, Least Bittern, Belted Kingfisher, Hairy Woodpecker, American Crow, White-breasted Nuthatch, Song Sparrow, Brown-headed Cowbird, American Redstart, Northern Parula, Yellow Warbler.    

Present - 8 Species: Rock Pigeon, Ring-billed Gull, Double-crested Cormorant, Great Blue Heron, Great Egret, Black Vulture, Turkey Vulture, Blackpoll Warbler.

Definition of Categories:

Confirmed Breeder: Any species for which there is at minimum evidence of a nest. A species need not successfully fledge young to be placed in the confirmed category.

Probable Breeder: Any species engaged in pre-nesting activity, such as a male on territory, courtship behavior, or even the presence of a pair, but for which there is no evidence of a nest. Since birds can and do sing and display to females during migration, this category cannot be used until the safe dates are reached.

Possible Breeder: Any species, male or female, observed in suitable habitat, but giving no hard evidence of breeding. Unless actively breeding, all birds in suitable habitat before the start of the safe date are placed in this category.

Present: Any species observed that is not in suitable habitat or out of its breeding range. It also applies to colonial water birds in the survey tract not associated with a rookery in the tract.

Definition of Safe Dates: We use safe dates as a means of deciding if a bird can be considered a breeder or a migrant. Safe dates are simply defined as a period of time beginning when all members of a given species have ceased to migrate in the spring and ending when they begin to migrate in the fall. Unless a bird is engaged in behavior that confirms breeding, it will be placed no higher than in the possible breeder category if it is observed outside the safe dates assigned to that species.

The Results of the 2018 Dyke Marsh Breeding Bird Survey

By Larry Cartwright, Breeding Bird Survey Coordinator

The 2018 Dyke Marsh Breeding Bird Survey was conducted between Saturday, May 26,and Wednesday, July 4, but any data collected outside of this period that confirmed a breeding species was entered into the database. This permitted us to filter out most migrants that do not use the marsh or surrounding habitat to breed. I also included information provided from the Sunday morning walks and reliable individuals to supplement data reported by the survey teams. The survey tract encompasses the Belle Haven picnic area, the marina, the open marsh, that portion of the Big Gut known as West Dyke Marsh that extends from the George Washington Memorial Parkway west to River Towers, the Potomac River from the shoreline to the channel and the surrounding woodland from the mouth of Hunting Creek to south of Morningside Lane.  

The breeding bird survey methodology uses behavioral criteria to determine the breeding status of each species that is recorded in the survey tract.  Species are placed into one of four categories: confirmed breeder, probable breeder, possible breeder and present.  We identified 65 species at Dyke Marsh during 2018. There were 38 confirmed breeding species, six probable breeders and 16 possible breeders.  An additional five species were listed as present, but either were colonial breeding waterbird species not using a rookery inside the survey tract or migrants still moving through northern Virginia to breeding areas further north. 

Only one male marsh wren (Cistothorus palustris) set up territory in this year's survey. Photo by Ed Eder

Those who have visited Dyke Marsh during the summer or have read these yearly breeding bird survey reports are aware of the plight of the marsh wren (Cistothorus palustris).  Marsh wren numbers declined over 15 years and the species ceased to be a breeder after 2014.  The breeding season of 2014 was the last time that volunteers documented multiple active nests.  In 2015 and 2016, a handful of marsh wrens appeared in the north marsh, with perhaps two or three males briefly establishing territory, but we could not confirm breeding.  During 2017, a canoe team on June 25 spotted a marsh wren carrying nesting material. A later survey team found three nests, one of which contained interior lining normally placed in an active nest by a female.  A male was observed close to the nest, and I determined that this situation was enough to confirm breeding. 

Unfortunately, our 2018 survey teams found no marsh wren nests, either active ones with attending females or dummy nests built by males to attract females.  All we located was a solitary male that briefly set up a territory north of the Haul Road peninsula for approximately two weeks in May and another lone male singing from the marsh vegetation in the Big Gut in the south marsh on July 1.  Volunteers neither saw nor heard additional marsh wrens in 2018, and with no evidence of breeding, the species once again lost its confirmed breeding status. 

	Least bittern (Ixobrychus exilis) numbers were down and were difficult to spot this year. Photo by Ed Eder

Least bittern (Ixobrychus exilis) numbers appeared down in 2018 compared to the previous year and it was difficult even to find them by canoe.  Four birds were seen on one trip in the Big Gut on July 4, but none appeared to be paired.  During the 2018 survey, we found only one likely breeding pair located in the narrowleaf cattails near the boardwalk at the end of the Haul Road peninsula. Subsequent searches yielded no fledged young and for the second straight year volunteers were unable to confirm least bittern as a breeder.    

I stated in last year’s report that least bitterns seemed to have withdrawn from the southern half of the Big Gut, primarily because of erosion and were concentrating their activities north of that point.  In 2017, an impressive nine birds were collectively recorded during one June day by three survey teams. Five of these birds, consisting of two pairs and a solitary individual, were in the north marsh and the remaining four were in the upper portion of the Big Gut. Volunteers found no birds in the lower Big Gut during the entire 2017 survey.  The same distribution of least bitterns repeated itself in 2018, but there were fewer birds.  

Blue-gray gnatcatcher (Polioptila caerulea) on nest. Photo by Ed Eder

The 2018 survey also shows that while some songbird species are successfully maintaining their populations in the wooded area adjacent to the marsh, others are possibly starting to decline.  Great crested flycatchers (Myiarchus crinitus), Eastern kingbirds (Tyrannus tyrannus), warbling vireos (Vireo gilvus), blue-gray gnatcatchers (Polioptila caerulea) and orchard orioles (Icterus spurius) continue to do well as we easily found high individual numbers, nests and fledged young for these species.  For example, a high count for warbling vireos was eleven during a June 18 survey.  Prothonotary warblers (Protonotaria citrea) also seem stable for now, primarily in the south marsh where there are enough cavities which they use for nesting.  

Yellow warblers (Setophaga petechia) and Baltimore orioles (Icterus galbula) may present a different story.  Yellow warbler nests usually can be found between the dogleg and the boardwalk at the end of the Haul Road peninsula.  Although one volunteer observed a female carrying nesting material in early May, we uncovered no yellow warbler nests or saw any fledged young throughout the rest of the survey, a truly odd occurrence.  As for Baltimore orioles, volunteers in 2018 tallied only one or two Baltimore orioles per survey compared to up to six individual orchard orioles. In previous years, numbers for the two oriole species have been roughly equal.  Nonetheless, we documented two Baltimore oriole nests and in mid-July, saw an adult feeding a fledged youngster, so despite lower individual numbers, the species remains a confirmed breeder. 

The truly puzzling species are the eastern wood-pewee (Contopus virens), Acadian flycatcher (Empidonax virescens), red-eyed vireo (Vireo olivaceus) and northern parula (Setophaga Americana), all common species in the mid-Atlantic states.  Eastern wood-pewees, Acadian flycatchers, and red-eyed vireos showed up at Dyke Marsh in May and June as they normally do and we expected them to establish territories.  Surprisingly, it appears that none did. A territory is defined as being established when a singing male is found at the same location after a week.  None of the males were found near the same spot on additional surveys as when they were initially identified, and none appeared to be present anywhere at Dyke Marsh after mid-June. And the northern parula? The first one wasn’t even identified until Independence Day, and this bird was probably a post-breeder arriving from outside Dyke Marsh.

So, what is happening to these songbirds?  Some species such as the Baltimore Oriole seem to be pushing its range north, so perhaps fewer are staying to breed in the mid-Atlantic. For other songbird species, a possible explanation is the death of all the Pumpkin Ash at Dyke Marsh. As the ash died along the periphery of the marsh, the defoliated trees left nests more exposed to predators like crows and brood parasites like Brown-headed Cowbirds.  This explanation does not provide a reason why some species continue to prosper while others appear more vulnerable, but it merits consideration. Additional surveys may provide answers. 

Ospreys (Pandion haliaetus) collectively built seven nests in 2018.  Bald eagles (Haliaeetus leucocephalus) disrupted osprey nesting attempts on Dyke and Coconut Islands in 2017 and ospreys did not try to build nests on either island in 2018.  There also was no nesting attempt on Bird Island because the nest tree toppled over during the previous winter.  Dyke Marsh did gain a new nest in 2018, but it was a rather pathetic affair. An apparently inexperienced osprey attempted to construct a nest in a tree in the parking lot of the marina, but nesting material fell faster from the nest than the bird could replace it.  The bird finally gave up and resumed construction in the woods adjacent to the south picnic area.  This nest held firm when completed, but by that time it may have been too late in the year to produce young.  This nest and another along the shoreline of the river east of the Big Gut were the only osprey nest failures of 2018.  The remaining five nests, including the now extremely popular one on the platform near the boat launch at the marina, fledged from one to three young. 

	Adult bald eagle (Haliaeetus leucocephalus) with nestling at Haul Road nest. Photo by Ed Eder

Bald eagles were highly successful during the 2018 breeding season.  The Haul Road bald eagle pair, in its first breeding season, produced a single nestling that successfully fledged by June 10.  Further south, the bald eagle pair occupying the nest just south of Tulane Drive fledged three young and the Morningside Lane nesting pair fledged at least one young.  Bald eagles have been nesting for a decade at Dyke Marsh and there is now no doubt that the species is an established breeder.     

The Dyke Marsh Breeding Bird Survey has a host of wonderful citizen-scientist volunteers whose efforts make the survey possible.  The Friends of Dyke Marsh and I as the compiler are grateful to all who volunteer time and expertise to gather essential data. Those who contributed to the 2018 Breeding Bird Survey are listed below.        

In alphabetical order, they are as follows: Mercedes Alpizar, Andy Bernick, Eldon Boes, Ashley Bradford, Ed Eder, Jane Gamble, Lori Keeler, Elizabeth Ketz-Robinson, Todd Kiraly, Larry Meade, Roger Miller, Gary Myers, Nick Nichols, Marc Ribaudo, Don Robinson, Laura Sebastianelli, Kimberly Sharp, Phil Silas, Robert Smith, Dixie Sommers, Carol Stalun, Sherman Suter, John Symington, Margaret Wohler, Katherine Wychulis, William Young.

Confirmed - 38 Species: Canada Goose, Wood Duck, Mallard, Mourning Dove, Osprey, Bald Eagle, Red-bellied Woodpecker, Downy Woodpecker, Northern Flicker, Eastern Phoebe, Great Crested Flycatcher, Eastern Kingbird, Warbling Vireo, Blue Jay, Fish Crow, Purple Martin, Tree Swallow, N. Rough-winged Swal- low, Barn Swallow, Carolina Chickadee, Tufted Titmouse, Caroli- na Wren, Blue-gray Gnatcatcher, American Robin, Gray Catbird, Northern Mockingbird, European Starling, House Sparrow, House Finch, American Goldfinch, Song Sparrow, Orchard Ori- ole, Baltimore Oriole, Red-winged Blackbird, Common Grackle, Prothonotary Warbler, Yellow Warbler, Northern Cardinal.

The 2018 Breeding Bird Survey Results:

Probable - 6 Species: Least Bittern, Pileated Woodpecker, Marsh Wren, Brown-headed Cowbird, Common Yellowthroat, Indigo Bunting.

Possible - 16 Species: American Black Duck, Wild Turkey, Chimney Swift, Ruby-throated Hummingbird, Green Heron, Black-crowned Night-Heron, Cooper’s Hawk, Hairy Woodpecker, Eastern Wood-Pewee, Acadian Flycatcher, White-eyed Vireo, Red-eyed Vireo, White-breasted Nuthatch, House Wren, Cedar Waxwing, Northern Parula.

Present - 5 Species: Caspian Tern, Double-crested Cormorant, Great Blue Heron, Great Egret, Magnolia Warbler.

Definition of Categories:

Confirmed Breeder: Any species for which there is at minimum evidence of a nest. A species need not successfully fledge young to be placed in the confirmed category.

Probable Breeder: Any species engaged in pre-nesting activity, such as a male on territory, courtship behavior, or even the presence of a pair, but for which there is no evidence of a nest. Since birds can and do sing and display to females during migration, this category cannot be used until the safe dates are reached. 

Possible Breeder: Any species, male or female, observed in suitable habitat, but giving no hard evidence of breeding. Unless actively breeding, all birds in suitable habitat before the start of the safe date are placed in this category.

Present: Any species observed that is not in suitable habitat or out of its breeding range.  It also applies to colonial water birds in the survey tract not associated with a rookery in the tract.  

Definition of Safe Dates

We use safe dates as a means of deciding if a bird can be considered a breeder or a migrant.  Safe dates are simply defined as a period beginning when all members of a given species have ceased to migrate in the spring and ending when they begin to migrate in the fall.  Unless a bird is engaged in behavior that confirms breeding, it will be placed no higher than in the possible breeder category if it is observed outside the safe dates assigned to that species.   

The Results of the 2017 Dyke Marsh Breeding Bird Survey

By Larry Cartwright, Breeding Bird Survey Coordinator

The 2017 Dyke Marsh Breeding Bird Survey was conducted between Saturday, May 27 and Tuesday, July 4, but any data collected outside of this period that confirmed a breeding species was entered into the database. This permitted us to filter out most migrants that do not use the marsh or surrounding habitat to breed. I also included information provided from the Sunday morning walks and reliable individuals to supplement data reported by the survey teams. The survey tract encompasses the Belle Haven picnic area, the marina, the open marsh, that portion of the Big Gut known as West Dyke Marsh that extends from the George Washington Memorial Parkway west to River Towers, the Potomac River from the shoreline to the channel, and the surrounding woodland from the mouth of Hunting Creek to south of Morningside Lane.

Our methodology uses behavioral criteria to determine the breeding status of each species that is recorded in the survey tract. Species are placed into one of four categories: confirmed breeder, probable breeder, possible breeder, and present. We found 87 species at Dyke Marsh during 2017. There were 46 confirmed breeding species, 8 probable breeders, and 11 possible breeders. An additional 14 species were documented as present, but either were not in suitable breeding habitat, were colonial breeding waterbird species not using a rookery inside the survey tract, or out of range.

A territorial Marsh Wren (Cistothorus palustris) in the south marsh. Photo by Ed Eder

Marsh wrens (Cistothorus palustris) were last confirmed as Dyke Marsh breeders in 2014 with approximately 16 singing males and fewer than a dozen nests confined to the marsh vegetation north of Haul Road. Marsh wrens disappeared from the Big Gut in the south marsh after 2006, but a few birds returned to occupy a tributary of the Big Gut that we unofficially call the Northeast Passage between 2011 and 2013. They failed to return to the south marsh in 2014. In 2015 and 2016 no more than three singing males were documented in the marsh surrounding Haul Road. There was no confirmed nesting and Marsh wrens dropped to a probable breeder status.

The same sparse representation of marsh wrens was present around Haul Road during the 2017 survey, but surprisingly two or three males in the south marsh occupied territory in the Northeast Passage after a three-year absence. During a June 25 survey, a canoe team spotted a marsh wren carrying nesting material. A subsequent canoe trip to the Northeast Passage reported three marsh wren nests. Two were apparent dummy nests, built by males to attract females. However, the third nest contained interior lining characteristic of active nests that are accepted and completed by females. A territorial male was close to the nest. Based on this information, I determined that this lone nest was active and met the criteria to confirm breeding.

I caution against interpreting this one active nest as potentially leading to a return of a viable marsh wren breeding population. The decline in the fortunes of this species at Dyke Marsh has been an ongoing process for over two decades. It may be part of a regional decline. Hopefully the marsh restoration will lead to some stability in the marsh habitat and in the absence of other unforeseen negative influences, the marsh wren may establish a presence that we can once again enjoy.

	A Least Bittern (Ixobrychus exilis) peers from the marsh vegetation on Dyke Island. Photo by Ed Eder

The least bittern (Ixobrychus exilis)is another species at Dyke Marsh that receives our special attention. Our survey teams have documented the retreat of least bitterns from the southern portion of the Big Gut, apparently because of the accelerated erosion. The data collected during the 2017 survey suggests that there is a strong presence of least bitterns at least in some areas of Dyke Marsh. Three separate surveys conducted on June 25, two by canoe and one by foot, collectively reported nine least bitterns. Five of the birds were in the north marsh, including two breeding pairs in a tributary of the Little Gut along the southern edge of the Haul Road peninsula, and the remaining four were in the upper portion of the Big Gut. Additional breeding pairs also were identified near the Northeast Passage and close to the boardwalk at the end of the Haul Road peninsula during other June surveys. Despite these apparent positive signs, we found no least bittern nests or fledged young and least bittern could only be listed as a probable breeder. My primary concern is that least bitterns are being forced into increasingly smaller areas of acceptable breeding habitat at Dyke Marsh and that these heavier concentrations will have a negative impact on breeding success. It seems odd to be able to document least bittern activity in northern locations of the marsh while the entire southern half of the Big Gut remains devoid of these birds.

An interesting relationship developed between ospreys (Pandion haliaetus) and bald eagles (Haliaeetus leucocephalus) at Dyke Marsh during the 2017 breeding season. Volunteers documented ten active osprey nests in an area extending from Porto Vecchio in the north to Angel Island in Pipeline Bay. Five of these nests, including the highly visible nest at the marina, produced fledged young while the remaining five failed. Two of the osprey nesting attempts were disrupted by a pair of bald eagles. The bald eagles in question could have been the Tulane Drive breedng pair, whose nest also failed by early April or a confused bald eagle duo that started building a nest along Haul Road in June when most eagle nests would be fledging young. A pair of bald eagles was first reported perched beside the osprey nest on Dyke Island on April 7, effectively blocking repeated attempts by the osprey breeding pair to access the nest. The bald eagles soon became interested in the osprey nest on the adjacent Coconut Island and perched beside this nest as well. With the larger and more dominant eagles controlling the situation on the islands, both osprey pairs eventually abandoned their breeding efforts. The bald eagles never made any attempts to destroy or use either the Dyke or Coconut Island nests but seemed content in just preventing the ospreys from using them.

Bald eagles did have a successful breeding record in 2017. The Morningside Lane breeding pair had at least one healthy, active youngster in the nest last seen on June 8. The bird apparently fledged within the following week.

A female Yellow Warbler (Setophaga petechia ) feeds a much larger Brown-headed Cowbird (Molothrus ater) fledgeling. Photo by Ed Eder

Dyke Marsh hosts a respectable number of neotropical migrant songbirds, including great crested flycatchers (Myiarchus crinitus), eastern kingbirds (Tyrannus tyrannus), warbling vireos (Vireo gilvus), yellow warblers (Setophaga petechia), orchard orioles (Icterus spurius), and baltimore orioles (Icterus galbula), that are confirmed as breeders every year. A walk down Haul Road will likely reveal all six species to the careful observer. Sometimes the careful observer turns out to be a female brown-headed cowbird (Molothrus ater). One observer on July 7 reported a bedraggled female yellow warbler feeding two brown-headed cowbird fledglings that were bigger and likely outweighed her.

Most songbirds are careful about concealing nests to protect them from predators and brood parasites like brown-headed cowbirds that victimized the unfortunate yellow warbler. Eastern kingbirds sometime don’t concern themselves with such incidentals as nest concealment. During a June 18 canoe survey into the Big Gut, I was surprised to find a completely exposed eastern kingbird nest with nestlings about 40 feet up in a dead sycamore. Another canoe team doing a different route on the same day also reported an exposed eastern kingbird nest containing nestlings, this one just four feet off the ground. Eastern kingbirds are quite aggressive and perhaps this aggressiveness just might help negate the need for complete caution and total nest concealment.

Several years ago, I noticed a trend for mallard (Anas platyrhynchos) hens to have delayed single broods or perhaps even multiple broods containing fewer young. In the 1990s, the norm would be to observe a mallard hen in April or May with perhaps a half dozen or more recently hatched young in tow. After 2000, volunteers noticed mallard hens with as few as two or three recently hatched ducklings much later in the summer. Volunteers still reported large broods after 2000, but with reduced frequency. The 2017 breeding season now holds the record for reduced size late broods at Dyke Marsh. On September 17, several volunteers observed a mallard hen in the marina in the company of two youngsters no more than one week old. A review of my records indicates that this is the first September record for breeding mallards since I became compiler in 1994. I have speculated in an earlier report that perhaps small broods were the result of increased predation of young, but significant loss of ducklings in a brood only a few days old seems highly unlikely. An egg predator would probably consume the whole clutch. Therefore, I tend to discount predation as a significant cause of small broods. We often see these small brood young several weeks after hatching and they appear quite healthy, so survival rates may be good in the first months of their lives. The data also shows that breeding bird survey observers often report the cavity nesting wood duck (Aix sponsa) with smaller than normal broods at Dyke Marsh. There may be explanations here that I have not yet entertained. Research continues.

The Dyke Marsh Breeding Bird Survey is impossible without the effort and dedication of participating citizen-scientists that conduct the surveys. This year’s participants included Eldon Boes, Glenda Booth, Marla Brin, Ed Eder, Myriam Eder, Renee Grebe, Susan Haskew, Gerry Hawkins, Elizabeth Ketz-Robinson, Dorothy McManus, Ginny McNair, Larry Meade, Roger Miller, Heidi Moyer, Sasha Munters, Nick Nichols, Rich Rieger, Don Robinson, Laura Sebastianelli, Phil Silas, Robert Smith, Karen Snape, Ned Stone, Sherman Suter, Todd Kiraly, Brett Wohler, Marcus Wohler and Margaret Wohler.

The 2017 Breeding Bird Survey Results:

Confirmed - 46 Species: Canada Goose, Wood Duck, Mallard, Mourning Dove, Ruby-throated Hummingbird, Osprey, Bald Eagle, Red-bellied Woodpecker, Downy Woodpecker, Pileated Woodpecker, Eastern Phoebe, Great Crested Flycatcher, Eastern Kingbird, Warbling Vireo, Red-eyed Vireo, Blue Jay, Fish Crow, Purple Martin, Tree Swallow, N. Rough-winged Swallow, Barn Swallow, Carolina Chickadee, Tufted Titmouse, Marsh Wren, Carolina Wren, Blue-gray Gnatcatcher, American Robin, Gray Catbird, Brown Thrasher, Northern Mockingbird, European Starling, Cedar Waxwing, House Sparrow, House Finch, American Goldfinch, Orchard Oriole, Baltimore Oriole, Red-winged Blackbird, Brown-headed Cowbird, Common Grackle, Prothonotary Warbler, Common Yellowthroat, Northern Parula, Yellow Warbler, Northern Cardinal, Indigo Bunting.

Probable - 8 Species: Chimney Swift, Least Bittern, Barred Owl, Hairy Woodpecker, Eastern Wood-Pewee, Acadian Flycatcher, White-breasted Nuthatch, Song Sparrow.

Possible - 22 Species: American Black Duck, Yellow-billed Cuckoo, Common Gallinule, Spotted Sandpiper, Green Heron, Black-crowned Night-Heron, Red-shouldered Hawk, Red-tailed Hawk, Eastern Screech Owl, Great Horned Owl, Belted Kingfisher, Northern Flicker, Willow Flycatcher, American Crow, House Wren, Wood Thrush, Eastern Towhee, Louisiana Waterthrush, Kentucky Warbler, American Redstart, Scarlet Tanager, Blue Grosbeak.

Present - 11 Species: Ring-necked Duck, Rock Pigeon, Ring-billed Gull, Caspian Tern, Forster’s Tern, Double-crested Cormorant, Great Blue Heron, Great Egret, Black Vulture, Turkey Vulture, Blackpoll Warbler.

Definition of Categories:

Confirmed Breeder: Any species for which there is at minimum evidence of a nest. A species need not successfully fledge young to be placed in the confirmed category.

Probable Breeder: Any species engaged in pre-nesting activity, such as a male on territory, courtship behavior, or even the presence of a pair, but for which there is no evidence of a nest. Since birds can and do sing and display to females during migration, this category cannot be used until the safe dates are reached. 

Possible Breeder: Any species, male or female, observed in suitable habitat, but giving no hard evidence of breeding. Unless actively breeding, all birds in suitable habitat before the start of the safe date are placed in this category.

Present: Any species observed that is not in suitable habitat or out of its breeding range.  It also applies to colonial water birds in the survey tract not associated with a rookery in the tract.  

Definition of Safe Dates

We use safe dates as a means of deciding if a bird can be considered a breeder or a migrant.  Safe dates are simply defined as a period beginning when all members of a given species have ceased to migrate in the spring and ending when they begin to migrate in the fall.  Unless a bird is engaged in behavior that confirms breeding, it will be placed no higher than in the possible breeder category if it is observed outside the safe dates assigned to that species.

The Results of the 2016 Dyke Marsh Breeding Bird Survey

By Larry Cartwright, Breeding Bird Survey Coordinator

The 2016 Dyke Marsh Breeding Bird Survey was conducted between Saturday, May 28 and Monday, July 4, but any data collected outside of this period that confirmed a breeding species was entered into the database. This permitted us to filter out most migrants that do not use the marsh or surrounding habitat to breed. I also included information provided from the Sunday morning walks and reliable individuals to supplement data reported by the survey teams. The survey tract encompasses the Belle Haven picnic area, the marina, the open marsh, that portion of the Big Gut known as the West Marsh that extends from the George Washington Memorial Parkway west to River Towers, the Potomac River from the shoreline to the channel, and the surrounding woodland from the mouth of Hunting Creek to south of Morningside Lane.  

The Dyke Marsh Breeding Bird Survey is undertaken as part of a continuing biological inventory of the tidal wetlands.  Our methodology uses behavioral criteria to determine the breeding status of each species that is recorded in the survey tract.  Species are placed into one of four categories: confirmed breeder, probable breeder, possible breeder, and present.  Volunteer teams in 2016 collectively reported 86 species at Dyke Marsh between May 28 and July 4. The 2016 list contains 44 confirmed breeding species, 12 probable breeders, and 16 possible breeders.  The remaining 14 species were present, but either were not in suitable breeding habitat, were colonial breeding waterbird species not using a rookery inside the survey tract, or out of range.  

Marsh Wrens failed to breed at Dyke Marsh for the second consecutive year. Possibly three males briefly established territories north of the Haul Road peninsula, that portion of the path from the dogleg to the boardwalk, but they appeared to abandon the effort by the middle of June. Least Bitterns had better success. As in 2015, Least Bitterns concentrated breeding efforts in the marsh vegetation surrounding Haul Road, in the tributaries of the Little Gut, and the upper portion of the Big Gut. However, only one or two birds were reported by each survey team in 2016 compared to 2015 when survey teams submitted weekly reports of three to five birds.   

Least bittern (Ixobrychus exilis) perched in ash tree near the boardwalk in Dyke Marsh. Photo by Ed Eder

I am unable to determine whether the reduction in Least Bittern numbers reflects an actual decline of Least Bitterns between 2015 and 2016 or if other factors were involved. Future surveys will give a clearer picture. We do know that a minimum of one Least Bittern breeding pair successfully raised young in 2016. A pair that was reported along the Haul Road boardwalk in early June was joined by a fledged youngster on July 9. 

The retraction of the Least Bittern from the lower portion of the Big Gut can be attributed to the heavy erosion occurring there. The complete disappearance of the Marsh Wren as a breeder around the Haul Road in 2015 may be part of a regional decline while erosion perhaps played a contributing factor in the elimination of the species as a breeder in the Big Gut almost a decade ago. Reliable reporters who frequent regional wetlands in Maryland, Virginia, and the District of Columbia have noted the decline and disappearance of Marsh Wrens in areas the birds used to inhabit.     

The usual contingent of migratory songbirds arrived at Dyke Marsh beginning in April and 

	A male orchard oriole (Icterus spurius) in a  sycamore tree brought a mayfly, a spider and worms to the nestlings. Photo by Ed Eder

had what seemed to be a particularly successful year.  There was a surprisingly high concentration of breeding activity between the Haul Road dogleg and the boardwalk. Volunteers documented five Orchard Oriole nests, two Baltimore Oriole nests, three Yellow Warbler nests, three Eastern Kingbird nests, one Warbling Vireo nest, and several Blue-gray Gnatcatcher nests along this stretch of the Haul Road. One Sycamore beside the wooden bridge hosted four nests! 

Survey team reports indicated that over half these nests, including all three Yellow Warbler nests, produced young. One Baltimore Oriole breeding pair nesting in a Sycamore near the short overlook path to the Little Gut was particularly lucky. On May 21 an observer noted crows attempting to ransack the nest while the orioles made a seemingly unsuccessful effort to protect it.  I jotted down in my notes that the nest had failed, but the orioles returned within a day.  Apparently the damage inflicted on the nest was minimal or at least repairable because the nest owners went on to produce healthy fledglings from this effort.  Blue-gray Gnatcatchers were exceptionally lucky in producing young on the Haul Road peninsula except for one breeding pair that was tending to a Brown-headed Cowbird.  This one documented case of brood parasitism seemed to be the exception as healthy young Blue-gray Gnatcatchers were easy to find as the breeding season progressed. 

The significant Pumpkin Ash die off may be having at least a temporarily beneficial impact on some cavity nesting species such as woodpeckers.  For example, a team conducting a canoe survey in the south marsh in early June reported two pairs of Hairy Woodpeckers.  Volunteers doing the same route three weeks later tallied five Hairy Woodpeckers, including an adult in the company of a fledged youngster.  A Sunday morning Dyke Marsh walk leader in the north marsh also noted an adult Hairy Woodpecker with a young bird.  These reports show a larger presence of Hairy Woodpeckers than observed in most previous years. Perhaps the number of dead trees in the wooded area has expanded feeding and breeding opportunities for the Hairy Woodpecker and similar species that use cavities.  

I found the presence of Eastern Bluebirds at two locations in the south marsh during 2016 quite interesting and wonder if it is also possibly related to the increased availability of nest cavities. Eastern Bluebirds have not been recorded as breeders in the 23 years that I have compiled the Dyke Marsh Breeding Bird Survey.  Yet a bird found at the Big Gut Bridge just north of Tulane Drive during Memorial Day weekend was still singing at this location on June 27, exactly a month later. The habitat at the Big Gut Bridge consists of trees with many snags for nesting, but limited feeding habitat for a ground foraging species like Eastern Bluebird, except for the strip of short grass lining the George Washington Memorial Parkway.  However, a report of a bluebird investigating a potential nest cavity at the southernmost point of Dyke Marsh suggests that this species might eventually be added to the list of Dyke Marsh breeding avifauna. 

My speculation about the expansion of nesting opportunities for some species that breed in cavities possibly contradicts a statement I made in my 2015 report concerning a likely decline in available cavities for Prothonotary Warblers, another Dyke Marsh breeder. Perhaps there really is no contradiction. Prothonotary Warblers have more selective nesting requirements than other cavity nesters.  We generally find Prothonotary Warbler nest cavities at Dyke Marsh no higher than eye level in a snag near or over open water.  Many of these snags are located along the banks of the south marsh and Big Gut, and seem to be falling over with increasing rapidity as erosion accelerates.  

It should not be surprising considering their habitat requirements that past surveys show Prothonotary Warbler males occupying territories almost exclusively in the south marsh and Big Gut.  In 2015, I estimate that up to nine Prothonotary Warblers established territories from the Big Gut Bridge to the southern tip of Dyke Marsh just below Morningside Lane.  No males were recorded in the north half of Dyke Marsh during the height of the 2015 breeding season.  

A different situation emerged in 2016.  Volunteers documented at the beginning of the survey up to three singing Prothonotary Warbler males along the Haul Road and adjacent Coconut (previously referred to as Cormorant) Island just east of the boardwalk.  It soon became clear that the birds were there not as a fluke, but had established territory.  There also appeared to be a corresponding decline of territorial males in the southern half of the marsh.  I have no ready explanation for this phenomenon, except to note that the wooded area around the Haul Road seemed to be wetter than in previous years and perhaps this provided the conditions suitable for breeding.  Whatever the case, on June 22, a male that multiple surveyors reported at or near the entrance of Haul Road since early June, was documented carrying food toward the marina, presumably to hungry nestlings. 

Ospreys constructed nine nests in the survey tract during 2016 and volunteers documented seven of these containing young.  The fate of the female Osprey occupying the platform nest at Porto Vecchio illustrates the dangers all that breeding birds potentially face.  It seems that during nest building, the birds brought sticks to the nest that contained fishing line filament.  Unfortunately, the female reportedly became entangled in the filament on April 18 and died before she could be rescued.  However, the remaining filament was removed, and the male amazingly secured another female to incubate the four eggs now in the nest.  And yes, this was one of the seven successful Osprey nests that produced healthy youngsters.  The popular marina nest produced two nestlings, one of which died soon after hatching, while the other went on to fledge before Independence Day.  

The Tulane Drive bald eagle (Haliaeetus leucocephalus) nest produced two fledged young.  Photo by Ed Eder

Finally, The Tulane Drive Bald Eagle nest produced two fledged young in 2016. Although all three resident owl species were present during the 2016 survey, the best we could find was a pair of Barred Owls.  There were no fledged owl young this year.  

The Dyke Marsh Breeding Bird Survey would not be possible except for the effort and dedication of the participating citizen-scientists that conduct the surveys.  The Friends of Dyke Marsh are grateful to all who volunteer time and expertise to gather accurate data that make this survey a success.  We extend a deep appreciation and thank you to all participants.  Those who contributed to the 2016 Breeding Bird is some capacity are listed below:         

In alphabetical order, they are: David Arnold, Eldon Boes, Glenda Booth, Ed Eder, Myriam Eder, Sandy Farkas, Kurt Gaskill, Susan Haskew, Gerry Hawkins, Lori Keeler, Elizabeth Ketz-Robinson, Claire Kluskens, Ginny McNair, Larry Meade, Roger Miller, Nick Nichols, Marc Ribaudo, Rich Rieger, Don Robinson, Laura Sebastianelli, Phil Silas, Ned Stone, Jessie Strother, Sherman Suter, Marcus Wohler, Margaret Wohler, Katherine Wychulis.

The 2016 Breeding Bird Survey Results:

Confirmed - 44 Species: Canada Goose, Wood Duck, Mallard, Least Bittern, Osprey, Bald Eagle, Mourning Dove, Red-bellied Woodpecker, Downy Woodpecker, Hairy Woodpecker, Northern Flicker, Acadian Flycatcher, Eastern Phoebe, Great Crested Flycatcher, Eastern Kingbird, Warbling Vireo, Blue Jay, American Crow, Fish Crow, Purple Martin, Tree Swallow, N. Rough-winged Swallow, Barn Swallow, Carolina Chickadee, Tufted Titmouse, White-breasted Nuthatch, Carolina Wren, Blue-gray Gnatcatcher, American Robin, Gray Catbird, Brown Thrasher, Northern Mockingbird, European Starling, House Sparrow, House Finch, Prothonotary Warbler, Common Yellowthroat, Yellow Warbler, Northern Cardinal, Red-winged Blackbird, Common Grackle, Brown-headed Cowbird, Orchard Oriole, Baltimore Oriole.

Probable - 12 Species: Barred Owl, Pileated Woodpecker, Eastern Wood-Pewee, White-eyed Vireo, Red-eyed Vireo, Marsh Wren, Eastern Bluebird, Cedar Waxwing, American Goldfinch, Norhtern Parula, Song Sparrow, Indigo Bunting.

Possible - 16 Species: Yellow-billed Cuckoo, Chimney Swift, Ruby-throated Hummingbird, Killdeer, Spotted Sandpiper, Green Heron, Black-crowned Night-Heron, Cooper’s Hawk, Redshouldered Hawk, Red-tailed Hawk, Eastern Screech Owl, Great Horned Owl, Belted Kingfisher, Willow Flycatcher, House Wren, Yellow-throated Warbler.

Present - 14 Species: Tundra Swan, Lesser Scaup, Rock Pigeon, Whimbrel, Laughing Gull, Ring-billed Gull, Herring Gull, Caspian Tern, Double-crested Cormorant, Great Blue Heron, Great Egret, Black Vulture, Turkey Vulture, Bank Swallow.

Definition of Categories:

Confirmed Breeder: Any species for which there is at minimum evidence of a nest. A species need not successfully fledge young to be placed in the confirmed category.

Probable Breeder: Any species engaged in pre-nesting activity, such as a male on territory, courtship behavior, or even the presence of a pair, but for which there is no evidence of a nest. Since birds can and do sing and display to females during migration, this category cannot be used until the safe dates are reached. 

Possible Breeder: Any species, male or female, observed in suitable habitat, but giving no hard evidence of breeding. Unless actively breeding, all birds in suitable habitat before the start of the safe date are placed in this category.

Present: Any species observed that is not in suitable habitat or out of its breeding range.  It also applies to colonial water birds in the survey tract not associated with a rookery in the tract.  

Definition of Safe Dates

We use safe dates as a means of deciding if a bird can be considered a breeder or a migrant.  Safe dates are simply defined as a period beginning when all members of a given species have ceased to migrate in the spring and ending when they begin to migrate in the fall.  Unless a bird is engaged in behavior that confirms breeding, it will be placed no higher than in the possible breeder category if it is observed outside the safe dates assigned to that species.

The Results of the 2015 Dyke Marsh Breeding Bird Survey

By Larry Cartwright, Breeding Bird Survey Coordinator

The 2015 Dyke Marsh Breeding Bird Survey was con-ducted between Saturday, May 23 and Sunday, July 5, but any data collected outside of this period that confirmed a breeding species was entered into the database. This permitted us to weed out most migrants that do not use the marsh to breed. I also included information provided from the Sunday morning walks and reliable individuals. In previous years, the survey tract encompassed the Belle Haven picnic area, the marina, the open marsh, the Potomac River from the shoreline to the channel, and the surrounding woodland from the mouth of Hunting Creek to south of Morningside Lane. In 2015 we added the West Marsh to the survey tract. The West Marsh is defined as that portion of the Big Gut and the surrounding woodland that lies west of the George Washington Memorial Parkway up to River Towers.

The Dyke Marsh Breeding Bird Survey is undertaken as part of a continuing biological inventory of the tidal wetlands. The breeding status of each species is determined by means of behavioral criteria. Species are placed into one of four categories: confirmed breeder, probable breeder, possible breeder, and present. Volunteer observers participating in the 2015 survey reported 84 species at Dyke Marsh between May 23 and July 5. The 2015 list contains 48 confirmed breeding species, four probable breeders, and 13 possible breeders. An additional 19 species were present, but either were not in suitable breeding habitat, were colonial breeding waterbird species not using a rookery inside the survey tract, or out of range.

Marsh wrens (Cistothorus palustris) dropped from confirmed breeder status in this year's survey. Photo by Ed Eder

There was a void in the marsh during the 2015 breeding season, a profound absence in the Narrowleaf Cattails that have supported the nests of Marsh Wrens for so many years. The Dyke Marsh breeding population of Marsh Wrens failed to arrive in 2015. Canoe teams reported two calling Marsh Wrens on the large island north of the Haul Road peninsula for the first time only in early July, but at that late date, I believe that these birds were possibly relocated failed breeders from another population. Whatever the case, Marsh Wrens dropped from their normal status as Dyke Marsh confirmed breeders to merely possible breeders in 2015.

The failure of Marsh Wrens in 2015 to arrive and occupy the marsh during spring migration in May was hardly unexpected. In her study of Marsh Wrens at Dyke Marsh in 1998 and 1999 as part of her Master’s Thesis, Population Abundance and Habitat Requirements of the Marsh Wren (Cistothorus palustris) at Dyke Marsh Wildlife Preserve: An Urban Conservation Challenge, Sandy Spencer found slightly less than three dozen territorial males at Dyke Marsh. Sandy pointed out that Marsh Wrens were once abundant along the Potomac River close to Washington DC, but were experiencing declines by the 1960s. Habitat loss was the overriding cause, but Sandy also saw additional problems with the Dyke Marsh breeding population, including high rates of nest predation, and narrow preferences for nesting territories. She speculated that this could put the Marsh Wren breeding population at risk over the long term.

Sandy’s concern was warranted. Soon after her study, the number of territorial or singing males dropped from less than three dozen to around 18. The decline was more immediately noticed in the Big Gut portion of the south marsh. The birds disappeared from the Big Gut for several years and then briefly returned between 2011 and 2013, with an active nest documented in 2013. Then in 2014, there were no Marsh Wrens to be found anywhere in the Big Gut.

The Marsh Wren population in the north marsh was centered around the Narrowleaf Cattails to the north of the Haul Road peninsula and the largest of the adjacent islands. After 2000, the number of singing male Marsh Wrens in the north marsh fluctuated from an estimated low of eight to a high of perhaps 16. In 2015, we had absolutely nothing except the late arriving males. The unfortunate loss of Marsh Wrens at Dyke Marsh may be a result of an overall regional decline exacerbated by conditions unique to Dyke Marsh, based on Sandy’s thesis and conversations with local experts and experienced birders (see article p. 2). We hope that the absence of Marsh Wrens will be temporary as we prepare for marsh restoration, but know that there are no guarantees.

	A recently fledged least bittern (Ixobrychus exilis) improving its fishing skills. Photo by Ed Eder

In contrast to the sad tale of Marsh Wrens, Least Bitterns appeared to have a decent breeding season. During the 2015 survey, Least Bitterns were concentrated in the tributaries of the Little Gut and the channel that separates the Haul Road peninsula from the largest island to the north. Volunteers reported smaller numbers of Least Bitterns at the end of the peninsula just east of the boardwalk, on the north side of the large island, and in the inlet adjacent to the north side of the dogleg. Numbers appeared to be slightly reduced in the Big Gut, but the birds were not impossible to find. It may be that Least Bitterns are gradually withdrawing from the southern half of the Big Gut, possibly as erosion accelerates, and concentrating in the northern half. That, however, is still speculation on my part and bears a close look during the 2016 survey.

Least Bittern youngsters were found, not surprisingly, in areas of their heaviest concentration during the 2015 survey. In late July, I received reports of a fledged Least Bittern and then a family group in the channel separating the Haul Road peninsula from the adjacent island followed a few days later by additional reports of a Least Bittern fledgling attempting to fish in the Little Gut. Admittedly, we conducted more Least Bittern dedicated surveys after Independence Day then we have in the past, but the effort produced positive results. Even during the regular survey, we found more breeding pairs in the marsh, including a pair copulating in one of the Little Gut tributaries, than I can remember in previous years.

I want to add that this does not mean that the Least Bittern will not meet the same fate as the Marsh Wren. One explanation might be that the birds are becoming more concentrated in remaining suitable habitat around the Haul Road peninsula as the marsh erodes in the south, and thus temporarily easier to find at these locations. However, crowded conditions may not be conducive to long term overall breeding success, and provides another reason to keep an eye on these birds in 2016.

Most of our Dyke Marsh raptors had a successful breeding year in 2015. The Morningside Bald Eagle nest was abandoned by January, 2015, but the new nest south of Tulane Drive fledged one healthy youngster by the first week in June. Ospreys constructed a total of 11 nests in the survey tract. Two of these nests were abandoned, but the breeding pair in both cases constructed new nests at different locations. Of the nine active nests, eight fledged youngsters. The highly visible and popular breeding pair at the marina nest saw its three nestlings take their first, but truncated flights, on July 1. One of the breeding pair that abandoned its original nest and rebuilt a second one also fledged youngsters, but at the end of July. Better late than never it seems!

Here a barred owl (Strix varia) looks down at its human observers. Photo by Jennifer Cowser

As far as nocturnal raptors are concerned, we hoped to confirm our Eastern Screech-Owl pair as Dyke Marsh breeders. Volunteers documented the pair together, and witnessed copulation, but we could not confirm breeding. That has been the case for several years now. We were in for quite a surprise, however. On April 12, several of us spotted a pair of Barred Owls in a tree in the wooded spot between Marina Road and the south picnic area. One of the birds was raising and lowering its head as if feeding nestlings, but we could not be sure. At least one of the owls was spotted twice after that and then on May 5, I saw the Barred Owl breeding pair near the Haul Road entrance accompanied by a fledged youngster. The Barred Owl family group was perched less than 30 feet from the traditional primary roost cavity of the Eastern Screech-Owls. That’s potentially bad news for an Eastern Screech-Owl because a Barred Owl can easily make a meal out of a smaller owl.

As far as our Dyke Marsh songbirds fared, Eastern Kingbirds, Warbling Vireos, and Orchard Orioles were present in expected decent numbers, and all were confirmed as breeders by the documentation of multiple nests or numerous fledged young and family groups for each species. In one instance, a Warbling Vireo pair in the north picnic area had difficulty with Eastern Kingbird neighbors as the vireos unsuccessfully attempted to prevent the kingbirds from demolishing their nest. Although not as numerous as Eastern Kingbirds, Warbling Vireos, and Orchard Orioles, Eastern Wood-Pewees and Red-eyed Vireos also fledged nestlings, although in one case the youngster being fed by a Red-eyed Vireo parent was a Brown-headed Cowird. American Crows bred at Dyke Marsh for the first time since 2003 when West Nile Virus swept through the area. Fish Crows have dominated the breeding scene at Dyke Marsh since then, but it appears that American Crows are working their way back into the picture.

	A song sparrow (Melospiza melodia) feeds a fledged youngster. Photo by Laura Sebastianelli

Baltimore Orioles and Prothonotary Warblers were tallied in the confirmed breeder category, but neither species seemed as numerous as in previous breeding seasons. In addition, Northern Parulas, not confirmed as 2015 breeders, seemed to be singing from fewer locations than last year. Maybe this is a result of normal yearly fluctuation in population size, but in the case of Prothonotary Warblers, the seemingly lower numbers may be a result of snags falling over at a faster rate, depriving perhaps some birds of an adequate choice of nest cavities. Brown-headed Cowbirds appeared to have a banner breeding year at Dyke Marsh in 2015, with Eastern Phoebe, Red-eyed Vireo, Song Sparrow, and Northern Cardinal all recorded as host parent species.

I feel personally indebted to all those who have taken the time and the effort to supply data as part of a survey team or who have led the Sunday morning walks during the survey period. Some of you have volunteered for many years, even going back over two decades when I became the survey’s compiler. Thanks so much to all of you. Those who contributed to the 2015 Breeding Bird Survey in alphabetical order are Dave Boltz, Jennifer Cowser, Ed Eder, Myriam Eder, Sandy Farkas, Kurt Gaskill, Susan Haskew, Gerry Hawkins, Ellen Kabat, Lori Keeler, Elizabeth Ketz-Robinson, Ginny McNair, Larry Meade, Roger Miller, Nick Nichols, Marc Ribaudo, Rich Rieger, Don Robinson, Laura Sebastianelli, Robert Smith, Ned Stone, Jessie Strother, Sherman Suter, John Symington, Meg Symington, Russell Taylor, Brett Wohler, Margaret Wohler and Katherine Wychulis.

The 2015 Breeding Bird Survey Results:

Confirmed - 48 Species: Canada Goose, Wood Duck, Mallard, Least Bittern, Osprey, Bald Eagle, Mourning Dove, Barred Owl, Red-bellied Woodpecker, Downy Woodpecker, Hairy Woodpecker, Northern Flicker, Eastern Wood-Pewee, Eastern Phoebe, Great Crested Flycatcher, Eastern Kingbird, Warbling Vireo, Red-eyed Vireo, Blue Jay, American Crow, Fish Crow, Northern Rough-winged Swallow, Purple Martin, Tree Swallow, Barn Swallow, Carolina Chickadee, Tufted Titmouse, White-breasted Nuthatch, House Wren, Carolina Wren, Blue-gray Gnatcatcher, American Robin, Gray Catbird, European Starling, Cedar Waxwing, Prothonotary Warbler, Yellow Warbler, Song Sparrow, Northern Cardinal, Indigo Bunting, Red-winged Blackbird, Common Grackle, Brown-headed Cowbird, Orchard Oriole, Baltimore Oriole, House Finch, American Goldfinch, House Sparrow.

Probable - 4 Species: Eastern Screech-Owl, Acadian Fly-catcher, Common Yellowthroat, Northern Parula. 

Possible - 13 Species: Green Heron, Black-crowned Night-Heron, Red-tailed Hawk, Spotted Sandpiper, Yellow-billed Cuckoo, Chimney Swift, Ruby-throated Hummingbird, Belted Kingfisher, Marsh Wren, Eastern Bluebird, Northern Mockingbird, American Redstart, Scarlet Tanager. 

Present - 19 Species: Lesser Scaup, Double-crested Cormorant, Great Blue Heron, Great Egret, Black Vulture, Turkey Vulture, Greater Yellowlegs, Whimbrel, Semipalmated Sandpiper, Bonaparte’s Gull, Laughing Gull, Ring-billed Gull, Herring Gull, Caspian Tern, Rock Pigeon, Gray-cheeked Thrush, Northern Waterthrush, Magnolia Warbler, Blackpoll Warbler.

Definition of Categories:

Confirmed Breeder: Any species for which there is at minimum evidence of a nest. A species need not successfully fledge young to be placed in the confirmed category.

Probable Breeder: Any species engaged in pre-nesting activity, such as a male on territory, courtship behavior, or even the presence of a pair, but for which there is no evidence of a nest. Since birds can and do sing and display to females during migration, this category cannot be used until the safe dates are reached. 

Possible Breeder: Any species, male or female, observed in suitable habitat, but giving no hard evidence of breeding. Unless actively breeding, all birds in suitable habitat before the start of the safe date are placed in this category.

Present: Any species observed that is not in suitable habitat or out of its breeding range.  It also applies to colonial water birds in the survey tract not associated with a rookery in the tract.  

Definition of Safe Dates

We use safe dates as a means of deciding if a bird can be considered a breeder or a migrant.  Safe dates are simply defined as a period beginning when all members of a given species have ceased to migrate in the spring and ending when they begin to migrate in the fall.  Unless a bird is engaged in behavior that confirms breeding, it will be placed no higher than in the possible breeder category if it is observed outside the safe dates assigned to that species.

The Results of the 2014 Dyke Marsh Breeding Bird Survey

By Larry Cartwright, Breeding Bird Survey Coordinator

The 2014 Dyke Marsh Breeding Bird Survey was conducted as part of a continuing biological inventory of the tidal wetlands. The breeding status of each species was determined by means of behavioral criteria. Species were placed into one of 4 categories: confirmed breeder, probable breeder, possible breeder, and present. 

The 2014 survey was conducted between Saturday, May 24 and Sunday, July 6, but any data collected outside of this period that confirmed a breeding species was entered into the database. This permitted us to weed out most migrants that do not use the marsh to breed. I also included information provided from the Sunday morning walks and reliable individuals to supplement data reported by the survey teams. The survey tract encompassed the Belle Haven picnic area, the marina, the open marsh, the Potomac River from the shoreline to the channel, and the surrounding woodland from the mouth of Hunting Creek to Morningside Lane. Volunteers found 84 species at Dyke Marsh during the survey. By the completion of data collection, 44 species had been confirmed as breeders, 6 species were listed as probable breeders, and 17 species as possible breeders. An additional 17 species were identified in the survey tract during the reporting period, but were considered not to be in suitable breeding habitat.  

The analyzed data indicates both good news and areas of continuing concern. Breeding woodpeckers seemed to do quite well in 2014 and volunteers observed Red-bellied, Downy, and Hairy Woodpeckers, and Northern Flickers all with fledged young. As in previous years, we discovered breeding Eastern Kingbirds, and Orchard and Baltimore Orioles everywhere that there were trees to host a nest. Territorial Warbling Vireos were singing from every possible location too, but it wasn’t until July 6 that the survey documented its first, and only, evidence confirming breeding, a nest near the boardwalk entrance. Observers reported possibly 2 Great Crested Flycatcher family groups in the south picnic area.   

A female yellow warbler (Setophaga petechia) is gathering spider silk for nesting material. Photo by Ed Eder

Survey teams did quite well on confirming the warblers. Prothonotary Warblers, Common Yellowthroats, Northern Parulas, and Yellow Warblers all were tallied as confirmed breeders. These warbler species are fairly common in the survey tract during the breeding season, but it can be exceedingly difficult to confirm all 4 of them. White-breasted Nuthatches were confirmed as breeders in late March when a pair began nest construction in a cavity at the Haul Road entrance, providing easy observation. Brown Thrashers, not always easy to find or even present at Dyke Marsh during the survey, were reported from several locations in 2014. I was delighted to find a Brown Thrasher pair near the Haul Road wooden bridge on June 18 followed by a report on July 8 of a ground foraging Brown Thrasher fledgling in the company of an adult near the boardwalk entrance.  

	A white-breasted nuthatch (Sitta carolinensis) female carrying nesting material. Photo by Ed Eder

Several confirmation misses are worthy of note. A Willow Flycatcher reported by multiple observers near the boardwalk from mid-May to early June apparently departed without attempting to breed. The now famous Eastern Screech-Owl pair put on quite a show in early March, copulating and giving every indication of preparing to breed, but we could not quite positively identify the nest cavity or locate young. A June 1 report of a Red-tailed Hawk pair near an empty nest in the south marsh was exciting news, but subsequent survey teams could not locate the pair or determine that the nest actually belonged to the hawks. Too bad, because Red-tailed Hawk has not been confirmed as a breeder in the 22 years that I have been compiler.  

Ospreys had a highly successful breeding season in 2014. Survey teams discovered 10 Osprey nests and eight of these eventually contained nestlings. A root ball nest off the picnic area that flooded out in early May and a tree nest along the stretch south of the Little Gut that was abandoned later that month were the only 2 failed nesting attempts. Of the successful endeavors, the platform nest near Porto Vecchio was the most productive, fledgling 4 youngsters. That may be a new record for the Dyke Marsh breeding bird survey. Another observer reported a nest with 4 nestlings near the island in Pipeline Bay, but I’m not sure that all of them fledged. 

This marina tilted nest with adults and nestlings was a success. Photo by Bill Young

The breeding Osprey pair at the marina nest perhaps had the most difficult time fledgling their 2 youngsters. During the winter, pressure from moving ice pushed the pole supporting the nest platform to a precarious 45 degree angle. We were amazed as we watched the Ospreys build the nest, adding more sticks to one side of the platform than the other to compensate for the lean. We held our breath as the 2 nestlings grew, hoping that the pole would not collapse or the nestlings slide out of the nest into the water. But fledge they did, and kudos to the Osprey breeding pair that made it happen!

There is a corollary to the marina Osprey nest story. A group of Purple Martins nested at the base of the platform of the marina nest during the 2012 and 2013 breeding season. On April 6, 2014 observers during a Sunday morning walk saw 4 Purple Martins flying around inspecting the platform, but the birds apparently decided that the lean was too great to try to nest there for a third year. So several found an alternative according to one report. They apparently nested in the masts of some of the inactive sailboats in the marina, and with some success. An adult was found feeding a fledged youngster in mid-July at the boardwalk. More fledglings were sighting in the following weeks. 

A new eagle nest along the tree line just west of the Little Gut was first reported under construction on December 21, 2013. Several observers noted some dark smudging in the tail of the smaller male eagle, indicating that he was probably only 4 or 5 years old, and likely a first time breeder. We watched the nest with much anticipation and everything seemed to be doing well until late March. On March 26 crows and Blue Jays were at the rim of the nest with no adult eagles in sight, not a good sign. Several of us assessed that it was the excessive cold our area experienced in late March that likely killed young nestlings and caused nest abandonment, and not just the presumed inexperience of the Bald Eagle breeding pair. On a happier note, the Morningside Lane Bald Eagle nest once again was successful, with the breeding pair fledgling its single nestling by mid-June.   

	Marsh wren (Cistothorus palustris) breeding status is a concern. Photo by Ed Eder

There remains much concern about the future of the Marsh Wren breeding population at Dyke Marsh. As in previous years, Marsh Wrens in the northern portion of Dyke Marsh were concentrated in the marsh vegetation on the north side of the Haul Road peninsula and the larger of the adjacent islands. By late June a canoe team could clearly see perhaps a half dozen nests in the Narrow-leaf Cattails as the surveyors transited the channel separating the peninsula from the island. By plotting locations of singing Marsh Wrens, I calculated that there was a minimum of 16 males on territory at this location. 

Unfortunately, there were no Marsh Wrens in the portion of the southern marsh that we refer to as the Big Gut in 2014. Indeed, there has been no reliable presence of Marsh Wrens in the Big Gut since 2000 when the breeding population throughout Dyke Marsh gave initial indications of a decline. After an absence of several years, a few Marsh Wrens occupied a tributary of the Big Gut in 2011 followed by a few more in 2012. By 2013 one survey team reported the presence of approximately a half dozen singing males and a minimum of 4 nests. One observer even documented a nest containing youngsters. Hope stirred that the Big Gut would host an even larger Marsh Wren presence in 2014. It didn’t. I’m confident Marsh Wrens will be at their usual location in the north marsh in 2015, but unwilling to make any prediction of what will happen in the Big Gut. The last decade and a half suggests it could go either way.   

The pattern and concentration of the Least Bittern population at Dyke Marsh increasingly seems to parallel that of the Marsh Wren. I assess that Least Bitterns are starting to focus their breeding efforts on the marsh vegetation around the Haul Road peninsula, to include the Little Gut. A canoe team tallied 5 Least Bitterns within 5 minutes of entering a tributary of the Little Gut on a June 7 survey. That includes a definite breeding pair. Another breeding pair was found near the north end of the boardwalk and at least a territorial male maintained a constant presence at the southern tip of the peninsula just off the boardwalk. In contrast, Least Bitterns south of the Little Gut seemed to be found primarily in the extreme upper portion of the Big Gut. Survey teams in the Big Gut reported no definite breeding pairs. Sightings or heard vocalizations were all of single birds. It may be that the rapid erosion in the lower portion of the Big Gut is making the habitat unsuitable for Least Bitterns.  

Unfortunately we were not able to confirm Least Bittern as a breeder anywhere in Dyke Marsh. Several light colored birds seen in flight along Haul Road towards the end of the survey could have passed as either adult females or fledged young. So Least Bittern went into the probable breeder category for 2014.   

Finally, I conclude with an example of a significant incident that occurred during the survey that demonstrates that some birds will take advantage of a seemingly bad situation. Most of you may recall a big storm event on June 18 that broke branches and felled many trees in the picnic area and along Haul Road. I’m sure that several active nests were destroyed and nestlings and some adults perished. Yet several Carolina Wren breeding pairs saw the wreckage as a golden opportunity to make another breeding attempt. Several observers found Carolina Wrens carrying nesting material into fresh cavities and crevices created by snapped tree trunks and broken branches within 10 days of the storm. On the downside, Carolina Wrens were observed for the second year in a row as the only species feeding fledged Brown-headed Cowbirds.  

This survey would not be possible without the hard work and dedication of so many volunteers who collected breeding bird data in 2014 as part of a Dyke Marsh survey team or who provided information as leader of a Sunday morning bird walk. I want to thank all those who contributed to the survey.    

In alphabetical order, they are: Bob Beard, Dave Boltz, Ed Eder, Myriam Eder, Sandy Farkas, Kurt Gaskill, Susan Haskew, Gerry Hawkins, Ellen Kabat, Elizabeth Ketz-Robinson, Dorothy McManus, Ginny McNair, Larry Meade, Roger Miller, Nick Nichols, Patrice Nielson, Marc Ribaudo, Rich Rieger, Don Robinson, Peter Ross, Molly Ross, Trish Simmons, Ned Stone, Jessie Strother, Paula Sullivan, John Symington, Maggie Symington, Bill Whitacre, Margaret Wohler, Katherine Wychulis.

The 2014 Breeding Bird Survey Results:

Confirmed - 44 Species: Canada Goose, Wood Duck, Mallard, Osprey, Bald Eagle, Mourning Dove, Red-bellied Woodpecker, Downy Woodpecker, Hairy Woodpecker, Northern Flicker, Great Crested Flycatcher, Eastern Kingbird, Warbling Vireo, Blue Jay, Fish Crow, Northern Rough-winged Swallow, Purple Martin, Tree Swallow, Barn Swallow, Carolina Chickadee, Tufted Titmouse, White-breasted Nuthatch, Marsh Wren, Carolina Wren, Blue-gray Gnatcatcher, American Robin, Gray Catbird, Brown Thrasher, European Starling, Cedar Waxwing, Prothonotary Warbler, Common Yellowthroat, Northern Parula, Yellow Warbler, Song Sparrow, Northern Cardinal, Red-winged Blackbird, Common Grackle, Brown-headed Cowbird, Orchard Oriole, Baltimore Oriole, House Finch, American Goldfinch, House Sparrow.

Probable - 6 Species: Least Bittern, Red-tailed Hawk, Eastern Screech-Owl, Acadian Flycatcher, Red-eyed Vireo, Indigo Bunting.

Possible - 17 Species: Pied-billed Grebe, Black-crowned Night-Heron, Mississippi Kite, Cooper’s Hawk, Killdeer, Spotted Sandpiper, Yellow-billed Cuckoo, Chimney Swift, Belted Kingfisher, Pileated Woodpecker, Eastern Wood-Pewee, Willow Flycatcher, American Crow, House Wren, Northern Mockingbird, American Redstart, Chipping Sparrow.

Present - 17 Species: American Wigeon, Ruddy Duck, Common Loon, Horned Grebe, Double-crested Cormorant, Great Blue Heron, Great Egret, Black Vulture, Turkey Vulture, Greater Yellowlegs, Ring-billed Gull, Caspian Tern. Rock Pigeon, Black-billed Cuckoo, Alder Flycatcher, Mourning Warbler, Blackpoll Warbler.

Definition of Categories:

Confirmed Breeder: Any species for which there is at minimum evidence of a nest. A species need not successfully fledge young to be placed in the confirmed category.

Probable Breeder: Any species engaged in pre-nesting activity, such as a male on territory, courtship behavior, or even the presence of a pair, but for which there is no evidence of a nest. Since birds can and do sing and display to females during migration, this category cannot be used until the safe dates are reached. 

Possible Breeder: Any species, male or female, observed in suitable habitat, but giving no hard evidence of breeding. Unless actively breeding, all birds in suitable habitat before the start of the safe date are placed in this category.

Present: Any species observed that is not in suitable habitat or out of its breeding range. 

Definition of Safe Dates

We use safe dates as a means of deciding if a bird can be considered a breeder or a migrant. Safe dates are simply defined as a period of time beginning when all members of a given species have ceased to migrate in the spring and ending when they begin to migrate in the fall. Unless a bird is engaged in behavior that confirms breeding, it will be placed no higher than in the possible breeder category if it is observed outside the safe dates assigned to that species.

President's Message

Summer / Fall 2021

Glenda Booth
FODM President

	Jack Oliver and his family helped pull stiltgrass from the native plant site  in August.

Message

The Origins of the Friends of Dyke Marsh

     The Friends of Dyke Marsh was formed in 1975 and incorporated in 1976. Since then, the group has grown and become more active in our work to protect the health of the Dyke Marsh Wildlife Preserve and to restore it.

     In the following article, one of FODM's founding members, the late Ed Risley, describes how and why the Friends of Dyke Marsh was formed.

The Friends of Dyke Marsh: Over Three Decades

Founding members and past FODM Presidents Ed Risley and Jeb Byrne. Photo by Ed Eder. -- by Ed Risley (Founding Member, FODM)

The origins of the Friends of Dyke Marsh, Inc. can be stated quite precisely: it followed a meeting of local activists and naturalists held with officials of the National Park Service on January 28, 1976. Of course there had been earlier "friends," notably Louis Halle, whose splendid book Spring in Washington (1945) was set in large part in Dyke Marsh; Irston Barnes whose articles in the Washington Post helped engineer the Act of Congress of 1969 which set aside the Marsh as a wildlife preserve; and Jackson Abbott who for years had been keeping records of sightings and leading bird walks. Nonetheless, by 1976 the area seemed virtually abandoned. No attempt will be made here to identify the numerous volunteers who gave their time and skill freely over the past three decades to preserve the Marsh.

The appearance of U.S. Army Corps of Engineers staff in the Marsh in late 1975 raised questions which the Park Service proposed be addressed at a meeting which was organized by the Audubon Naturalist Society (ANS). I was on the ANS Conservation Committee and put together a list of attendees. In addition to publicizing possible plans for expanding the Marsh, it was agreed that an environmental assessment would be prepared and that the public should be involved through a continuing committee (the Friends!). In short order officers were elected and a charter was adopted. Later, articles of corporation were adopted and Friends' objectives were agreed to. Above all, the goal of the Friends was to preserve the remnant but valuable fresh water tidal marsh against a multitude of human and natural threats.

A number of steps were agreed to, first by the new committee and in the years since:

1. To promote awareness, regular meetings were set up (now on a quarterly basis at Huntley Meadows Park Visitors Center) open to the public. Speakers on topics generally related to the Marsh were recruited.
2. A newsletter was published, at first sporadically and later on a quarterly basis. To maintain visibility and credibility members wrote letters to editors and contributed to periodicals such as Audubon and the Washington Post. A large aerial photo was purchased and made part of a traveling exhibit. Brochures and bird lists were produced and distributed.
3.  Relations with the Federal managers were strengthened. The Corps of Engineers backed off and the impact statement abandoned, but relations with the Park Service were strengthened although every few years there would be a new set of officials to deal with. In 2000 the Friends were formally recognized as a collaborating partner of the National Park Service. Our contribution was to participate in regular Marsh cleanups and to host and guide school groups and other visitors. Periodic meetings are held with the Superintendent to discuss issues and problems.

As the area around Dyke Marsh has become urbanized various human problems have been aggravated. Some problems such as hunters, commercial fishing, drug use and public immodesty were clearly illegal and gradually reduced. FODM has over the years engaged in a variety of issues, including application of herbicides in the marsh, impact on the marsh of Belle Haven Marina, the construction of the new Wilson Bridge and National Harbor. Such activities continue. FODM has also worked with the National Park Service on a boardwalk for Dyke Marsh, and after its destruction by Hurricane Isabel, now a new one.

A major positive activity of the Friends has been collecting and organizing data of all elements of the natural environment. Over $30,000 has been collected and spent to gain Dyke Marsh entry in the Virginia State Department of Natural Resources files and to collect data on, especially, the bird life including annual winter census and breeding bird surveys. Collection of data also includes results of the weekly bird walks led by expert birders. Other flora and fauna are the subject of ongoing collection efforts which we support and already have published in a pamphlet prepared by a trained biologist.

After three decades, members can look back with satisfaction on the camaraderie of regular meetings, the contribution of volunteer work and the gains in understanding the natural ecology at their doorstep. It is clear that threats to the integrity of Dyke Marsh will never cease. Buffeted by natural and manmade forces, the continuation of the Friends is essential.

Membership

How to become a Member of FODM

You can join, renew and donate online or by U.S. Postal Service mail.

Membership in the Friends of Dyke Marsh is $20 a year per household or $250 for an individual life membership. You can sign up or renew for one or more years. We will send members reminders to renew as their membership expiration date approaches. We will send the notices via email or postcard.

We welcome your contributions of any amount to help us preserve and restore Dyke Marsh. Thank you.

Membership and Donations Online:

Just click on the orange "Join/Renew/Donate" button in the right column to join or make a non-membership donatation.  Members who wish to renew or make an extra donation must log in first. If you do not remember your login username or password, send an email to This email address is being protected from spambots. You need JavaScript enabled to view it. and we will send you login and payment instructions.

Membership and Donations by Mail:

Please send us your membership dues along with your name, address, phone number and email address. Please indicate the amount of your donation that is for dues and the amount for any additional contribution. We will send our quarterly newsletter, The Marsh Wren, to members by email in  *.pdf  format for people for whom we have an email address. For those who do not provide an email address, we will send you a paper copy by the U.S. Postal Service mail.

Dr. Edd Barrows leads a group of students in study along Haul Road. Photo by Robert Smith.

 Friends of Dyke Marsh
P.O. Box 7183
Alexandria, VA 22307-7183

$20.00 / Household - Per Year
$250 Individual Lifetime Membership
Tax Deductible

A financial statement is available upon written request from the Virginia Office of Charitable and Regulatory Programs.

About FODM

Dr. Elizabeth Wells leads plant walks in Dyke Marsh. Photo by Glenda Booth.The Friends of Dyke Marsh (FODM) was formed in 1976 by a group of local people who, initially, wanted to stop plans to use the marsh as a dumping ground for dredged river spoil. This was yet another insult to the wetland; in the 1930s, construction debris had been heaped into the marsh and some of it is still visible today. The group formally organized as a non-profit organization for the purpose of cooperating with the U.S. National Park Service (NPS) in promoting the well-being of the marsh and preserving and restoring it. FODM was incorporated in 1976.

Since 1975, the Friends have continued and expanded their volunteer work. Our efforts include holding quarterly meetings and other programs open to the public; publishing a newsletter titled The Marsh Wren; raising money to sponsor scientific studies of the marsh; conducting nature walks; conducting surveys, including the annual breeding bird survey; hosting trash cleanups; preparing informational materials; encouraging public stewardship; maintaining this website and a Facebook page; and helping NPS control invasive Lew Cabe is a member of the FODM team that works to control non-native, invasive plants. Photo by Glenda Booth.plants.

The Friends also advocate for conservation and restoration and oppose inappropriate activities that degrade the health of the marsh as a wildlife habitat. For a more complete history of the park and the Friends of Dyke Marsh, see Dyke Marsh Wildlife Preserve, A Chronology.

Our Mission

The Friends of Dyke Marsh are dedicated to preserving, protecting and restoring the Dyke Marsh Wildlife Preserve, in partnership with the National Park Service, as a vital wildlife habitat, through education, science, advocacy and stewardship. Our vision is that Dyke Marsh will someday be a healthy, vital, self-sustaining, biodiverse ecosystem.

Thanks go to our many supporters, including many public officials.

FODMers Work to Protect and Restore Dyke Marsh

Some Examples of What We Do

Sponsor programs

Monarch butterfly expert Larry Brindza gave a presentation to FODMers describing how he catches and tags monarch butterflies.

Caroline Seitz of Reptiles Alive used live reptiles in her presentation to FODMers. This alligator is not found in Dyke Marsh.

Support Science

FODM supported a dragonfly and damselfly survey in the preserve, conducted by Chris Hobson of the Virginia Natural Heritage Program, which he presented at a FODM meeting in 2012. 

FODMers conduct surveys, for example, of reptiles and amphibians.

Lead nature walks

FODMers lead bird walks every Sunday morning at 8 a.m.

FODM volunteers co-lead a plant walk every fall.

Conduct surveys

For over 20 years, FODMers have conducted a breeding bird survey. Larry Cartwright organizes it, compiles records of breeding birds and submits data to the National Park Service.
     Larry Cartwright, leader of the annual breeding bird survey, and Laura Sebastianelli surveyed birds in the western part of Dyke Marsh for the first time in July 2015.

Introduce decision-makers to Dyke Marsh

In July 2015, with the assistance of NPS biologists Erik Oberg (steering the boat) and Brent Steury, FODM introduced two of Congressman Beyer's staff to the Dyke Marsh Wildlife Preserve. Standing:  Kate Schisler.   Seated:  ChoYi Kwan.
      On October 24, 2013, Department of Interior Secretary Sally Jewell came to Dyke Marsh to announce the award of a $25 million grant to restore Dyke Marsh. Seated:  Congressman Jim Moran; Secretary Jewell; Virginia Senator Tim Kaine; Virginia Delegates Rob Krupicka and Scott Surovell.

Host school and other groups

Since 2012, students from the T.C. Williams High School International Academy have visited Dyke Marsh in the spring to learn and help control invasive plants.

 Students from nearby Belle View Elementary School visit Dyke Marsh.  NPS Ranger Emily Zivot helped us describe the spatterdock to them.

Encourage public stewardship

FODM participates in the Gum Springs Community Day. Here Ned Stone helps a young visitor make a paper bird.

FODM and National Park Service staff introduce the next generation to environmental stewardship.  Here Laura Sebastianelli, in NPS uniform, and Greg Crider, FODMer, discuss insects with Mara and Colin Surovell.

Organize trash cleanups

FODMers participate in the annual Alice B. Ferguson Potomac River Trash Cleanup every spring and conduct other cleanups throughout the year.

Community groups like the Girl Scouts help us clean up trash. 

Attack invasive plants

NPS staffer Kenneth Adams helps train volunteers. Here he tackles the very invasive porcelainberry.

Members of the Student Conservation Corps help FODMers try to control invasive plants. 

The Dyke Marsh Wildlife Preserve, like many Northern Virginia properties, is unfortunately riddled with non-native plants. Areas on both sides of the Dyke Marsh Haul Road, the walking trail, are particularly overwhelmed with invasives, like many areas in northern Virginia. Invasive plants are often found in disturbed areas. The Haul Road, as fill, is a classic example. It was built as a service road by the people who dredged and hauled away half of Dyke Marsh between 1940 and 1973.     Fortunately, the National Park Service (NPS) is trying to better control these plants, but it is truly an uphill battle. Non-natives do not co-evolve with native insects and other animals and usually provide little food value to wildlife. NPS biologist Erik Oberg calls invasive plants like bush honeysuckle “junk food” for birds. Plants like orcelainberry and English ivy can outcompete, destroy and smother native, understory plants.     Porcelainberry vines smother trees, shrubs and plants in summer and fall (see photo, right by G. Booth). FODM volunteers work to control invasive plants. To volunteer, visit our Volunteer / Help page.

Birding and Conservation Groups

Local

• Alexandria Seaport Foundation
• Audubon Naturalist Society of the Central Atlantic States
• Audubon Society of the District of Columbia (DC Chapter of the National Audubon Society)
• Audubon Society of Northern Virginia
• Chesapeake Bay Foundation (Save the Bay)
• Entomological Society of Washington
• Four Mile Run Conservatory Foundation
• Friends of Huntley Meadows Park (Alexandria, VA)
• Friends of Little Hunting Creek
• Friends of Mason Neck State Park
• Georgetown University Laboratory of Entomology and Biodiversity (Dyke Marsh research and photos)
• Maryland Ornithological Society (Links to all Maryland Chapters)
• Mt. Vernon Sierra Club
• Northern Virginia Bird Club (Northern Virginia Chapter of the Virginia Society of Ornithology)
• Potomac Appalachian Trail Club
• Potomac Conservancy
• Potomac Riverkeeper
• Virginia Bluebird Society
• Virginia Department of Conservation and Recreation Natural Heritage Program
• Virginia Department of Game and Inland Fisheries (Web page of the Virginia Birding & Wildlife Trail)
• Virginia Institute for Marine Science
• Virginia Native Plant Society (State)
• Virginia Native Plant Society (Potowmack Chapter)
• Virginia Natural History Society
• Virginia Society of Ornithology
• Wetlands Watch

National

• American Bird Conservancy
• American Birding Association
• Boreal Songbird Initiative
• Cornell Lab of Ornithology
• Ducks Unlimited
• Monarch Watch
• National Audubon Society
• National Park Service
• National Parks Conservation Association
• National Wildlife Federation
• The Nature Conservancy
• World Wildlife Fund

Why Should Dyke Marsh Be Restored?

For many years, the Friends of Dyke Marsh have advocated for the stabilization and restoration of the marsh. Two U.S. Geological Survey (USGS) studies found that the marsh is eroding and could be completely gone by 2035. For a full explanation, see “The Problem” below.

Fortunately, the National Park Service prepared a restoration plan, described below, and contracted with Coastal Design and Construction to build a breakwater and five sills to stabilize the marsh and encourage sediment accretion.

The breakwater replicates a natural promontory that the USGS study maintains protected the marsh.

In November 2022, Coastal Design and Construction completed that work. The following is a brief chronology of the stabilization and restoration work.

Two Phases of Restoration Completed

In November 2022, Coastal Design and Construction completed construction of sills north of  the breakwater. These structures are intended to provide buffers against storms, stem erosion and encourage accretion in the marsh.

Dyke Marsh Restoration, Phase 2 Is Approved

On June 22, 2021, the Virginia Marine Resources Commission unanimously approved the National Park Service’s permit to construct 1,720 linear feet of rock sill in Dyke Marsh, effectively extending the current sill northward. This is considered to be phase two of the restoration and stabilization project. On November 4, the National Park Service awarded a contract for phase two to Coastal Design and Construction, Inc.

Dyke Marsh Restoration, Phase 1 Is Completed

In February 2020, the marine engineering firm that contracted with the National Park Service to begin Dyke Marsh restoration completed phase one.  Coastal Design and Construction, Inc., built a 1,500-foot breakwater and a sill in the south marsh.  The breakwater is designed to replicate the former protective promontory removed by dredgers who hauled away over half of Dyke Marsh between 1940 and 1972.

Coastal Design and Construction has a contract with the U.S. Army Corps of Engineers, Baltimore District.  Managers estimate that the project could take up to 18 months.

The breakwater is the first stage of restoration.  U.S. Geological Survey and National Park Service (NPS) studies identified a breakwater in the southern marsh as the top restoration priority.  The breakwater is designed to replicate the historic promontory removed by dredgers between 1940 and 1972.  Destroying the promontory altered the hydrology of the marsh.  The breakwater would “redirect erosive flows in the marsh, particularly during strong storms and would re-establish hydrologic conditions that would encourage sediment accretion,” says the NPS 2014 plan.

Permits

In September 2017, the Fairfax County Wetlands Board, on a five to zero vote, approved a wetlands permit.  On March 27, the Virginia Marine Resources Commission (VMRC), on a five to two vote, approved a permit for NPS to begin part of the Dyke Marsh restoration project.  Generally, the permit application had two parts: (1) construction of a 1,500-foot breakwater to replicate the former promontory that protected the marsh and (2) restoration of 5.45 acres of wetland lost to dredging.  VMRC approved the 1,500-foot riprap breakwater and stipulated that work on that could begin soon.

However, citing concerns about the impacts to submerged aquatic vegetation, VMRC only approved 1.5 acres of restoration, about one fourth of what NPS sought approval for and a small fraction of the 40 acres originally envisioned in phase one of NPS’s 2014 restoration plan, a plan that also envisions restoring up to 150 acres in future phases.

“We are very disappointed,” said Doug Jacobs of NPS’s National Capital Region office. “Restoring one and a half acres falls far short of our goal and it does not meet the Congressional directive to restore Dyke Marsh. Restoration was also a key purpose of the Hurricane Sandy grant. Nonetheless, we still hope to advance the project.”

In addition to Jacobs, FODMers Glenda Booth, Katherine Wychulis and Jessie Strother gave supportive testimony at the hearing. No one opposed the application at the hearing.

Click here to read the statements of the three FODM representatives to VMRC: Glenda Booth - Katherine Wychulis - Jessie Strother

On May 28, 2019, the Virginia Marine Resources Commission unanimously approved a permit modification authorizing the National Park Service to start phase two of restoration. Under the revised permit, the contractor will build a rock sill at the three-foot contour offshore of the southern marsh shoreline just north of the breakwater currently under construction. The sill will have gaps so that water and aquatic organisms will flush in and out with the tides.  Because the sill will impact some submerged aquatic vegetation (SAV), NPS is required to mitigate those impacts by funding a submerged aquatic vegetation project at a cost of $160,000 at, as of August 2019, an undetermined location within the Chesapeake Bay watershed.

As of early August, the submerged portion of the breakwater was about 90 percent completed; the part visible at low tide is around one-third completed.

The Dyke Marsh shoreline is eroding 1.5 to two acres a year. Photo by Glenda Booth.Dyke Marsh Is Disappearing

Dyke Marsh will be gone by 2035, 20 years from now, without action, predicts the U.S. Geological Survey (USGS). The marsh is losing 1.5 to two acres a year and the rate of erosion is accelerating.

In a 2013 update to their 2010 landmark study, USGS reported, "We ultimately conclude that Dyke Marsh presently is in its late stages of failure as a freshwater tidal marsh system. Bathymetry data confirm that tidal creeks are stripping sediment from the marsh, rather than aggrading it onto the marsh. Erosion is fragmenting the marsh and dismantling tidal creek networks by stream piracy. In the absence of human efforts to restore the equilibrium between marsh and tide, and equilibrium to the other natural forces acting on this wetland, Dyke Marsh likely will continue to accelerate its degradation, erosion, and fragmentation until it is gone. This likely will occur prior to 2035 AD."

Dyke Marsh erosion and loss from 1937 to 2006. Click photo to enlarge.The Problem

In 1940, Dyke Marsh was around 180 acres in size. By 2010, it was around 53 acres, said USGS. The USGS scientists wrote, “Analysis of field evidence, aerial photography, and published maps has revealed an accelerating rate of erosion and marsh loss at Dyke Marsh, which now appears to put at risk the short term survivability of this marsh.”

The USGS 2010 study also had these findings:

• Dredging of sand and gravel from 1940 to 1972 was a strong destabilizing force, transforming it from a net depositional state to a net erosional state. Dredging removed around 101 acres or 54 percent of the 1937 marsh.

2010 USGS Study• Erosion is both continuous and episodic. The changes caused by dredging have made the marsh subject to significant erosion by storm waves, especially from winds traveling upriver. Damaging storms occur approximately every three years.

• Mining or removing the promontory on the southern end of Dyke Marsh removed the geologic wave protection of the south marsh that existed back to at least 1864 and altered the size and function of the tidal creek network.

• “This freshwater tidal marsh has shifted from a semi-stable net depositional environment (1864–1937) into a strongly erosional one . . . The marsh has been deconstructed over the past 70 years by a combination of manmade and natural causes. The marsh initially experienced a strong destabilizing period between 1940 and 1972 by direct dredge mining of the marsh surface. By 1976 the marsh had entered a net destructive phase, where it remains at present.”

• The minimal protection needed to protect and enhance natural deposition includes a wave break in the location of the former promontory.

The U.S. Geological Survey study is titled Analysis of the Deconstruction of Dyke Marsh, George Washington Memorial Parkway, Virginia: Progression, Geologic and Manmade Causes, and Effective Restoration Scenarios and was written by Ronald J. Litwin, Joseph P. Smoot, Milan J. Pavich, Helaine W. Markewich, Erik Oberg, Ben Helwig, Brent Steury, Vincent L. Santucci, Nancy J. Durika, Nancy B. Rybicki, Katharina M. Engelhardt, Geoffrey Sanders, Stacey Verardo, Andrew J. Elmore and Joseph Gilmer. It is on the USGS website here.

Historic Imagery Viewer Shows Changes over Time

Fairfax County has an imagery viewer that can help people understand the extent of the wetland in the past and provide context for marsh restoration. For more information, click here.

The NPS Restoration Plan

NPS Natural Resources Manager Brent Steury discusses the plan with FODM board member Trudi Hahn.  Photo by Glenda Booth.The NPS Dyke Marsh Restoration PlanThe National Park Service (NPS) published the final Dyke Marsh Restoration and Long-term Management Plan on October 9, 2014 in the form of an environmental impact statement (EIS). Among other objectives, the plan would restore wetlands and ecosystem functions and processes and protect the remaining wetland. Restoration would also increase the resilience of the marsh, provide a buffer to storms and control flooding, states the EIS. NPS maintains that their restoration plan would bring beneficial impacts to the marsh's hydrology, sediment transport, vegetation and wetlands and stabilize erosion.
Alternative C
Click image to enlargeNPS’s plan or preferred alternative is “alternative C,”  the “fullest possible extent of wetland restoration,” an approach which would restore up to 180 acres of wetland habitats in stages. The Friends of Dyke Marsh support alternative C. NPS would restore the marsh in a phased approach “up to the historic boundary of the marsh and other adjacent areas within NPS jurisdictional boundaries, except for the area immediately adjacent to the marina.”
In phase one, NPS would build a breakwater in the southern part of the marsh to replicate the promontory removed by dredgers and identified by USGS as critical to protecting and restoring wetland habitat. "Phased restoration would continue until a sustainable marsh is achieved . . . .," says the plan.

Other steps:
• fill the deep channels created by dredging;
• restore emergent marsh within the area of the historic promontory;
• build containment cells within the historic boundary. "The location of these cells would be prioritized based on the most benefits of the specific locations could provide to the existing marsh. . . ."
• restore marsh along the edge of existing marsh to wherever the water is less than four feet deep; and
• install breaks in the Haul Road to "reintroduce tidal flows west of the Haul Road" and to restore the swamp forest.

FODM Supports Restoration

FODM Restoration Flyer
Click image to enlarge.The Friends of Dyke Marsh have advocated for restoration of Dyke Marsh since the organization's founding in 1976. FODM believes that a restored marsh can restore coastal resiliency, buffer the area against some storm activity, restore more habitat for birds, fish and other wildlife; restore more native wetland plants and other biota; create a healthier overall ecosystem, and if restored, provide more opportunities for research, nature study and educational, recreational and other nature-oriented activities. A restored Dyke Marsh can be a more robust outdoor classroom for hundreds of students of all ages and a natural laboratory for scientists and others.

Restoration Funds Are Available

Thanks to broad support, funding is available, from two sources:

1. MWAA Mitigation Funds

On March 27, 2013, the Metropolitan Washington Airports Authority (MWAA) made available to the National Park Service (NPS) $2.5 million for construction of a "promontory structure breakwater." The breakwater would be designed to replicate the historic promontory in the southern end of the marsh that protected Dyke Marsh, but was removed by Smoot Sand and Gravel. The USGS study maintains that a replacement promontory would provide a buffer against storms and flooding, encourage accretion and deposition of sediment and restore ecosystem services that benefit the Potomac River, the Chesapeake Bay and the community. The airport funds represent compensatory mitigation for impacts of a runway extension, an airport landing safety area, required to meet Federal Aviation Administration safety standards.

NPS and MWAA received 80 public comments, almost all of which were supportive. Among those who sent supportive comments were Congressmen Jim Moran and Gerry Connolly; Sharon Bulova, Chair, Fairfax County Board of Supervisors; William Euille, Mayor of Alexandria; the Northern Virginia Conservation Trust; the National Parks and Conservation Association; the Nature Conservancy (Virginia); the Potomac Conservancy; the Audubon Society of Northern Virginia; the Audubon Naturalist Society; the Mount Vernon Council of Citizen Associations and the Virginia Conservation Network.

2. Department of Interior, $25 Million in Resiliency Funds

Secretary Jewell makes the announcement flanked by Senator Tim Kaine, D-VA (left), Congressman Jim Moran, D-VA and FODM president Glenda Booth. Photo by T.D. Hobart.U.S. Secretary of Interior Sally Jewell on October 24, 2013 came to the Dyke Marsh Wildlife Preserve and announced the award of a $24.9 million grant to restore Dyke Marsh, part of President Barack Obama’s Hurricane Sandy Rebuilding Strategy and Climate Action Plan to build resilience by restoring natural features along shorelines and to protect communities from storms. Virginia U.S. Senator Tim Kaine, a staffer for U.S. Senator Mark Warner, Eighth Congressional District Congressman Jim Moran and Alexandria Councilwoman Allison Silberberg attended.Secretary Jewell said, “What we witnessed during Hurricane Sandy was that our public lands and other natural areas are often the best defense against Mother Nature. By stabilizing marshes and beaches, restoring wetlands, and improving the resiliency of coastal areas, we not only create opportunities for people to connect with nature and support jobs through increased outdoor recreation, but we can also provide an effective buffer that protects local communities from powerful storm surges and devastating floods when a storm like Sandy hits.”The announcement is on the Department of the Interior website and a video is here.

Why is Dyke Marsh Significant?
FODM has published a flyer outlining the significance of Dyke Marsh and why we should care about the health of this valuable resource. Click image at right.

Summary

• Without restoration, Dyke Marsh will be gone in 20 years.

• NPS has prepared a restoration plan.

• Funds are available to complete most of the restoration.

• The National Park Service should implement the restoration plan.

Why Should Dyke Marsh Be Restored?

Rare: Dyke Marsh is a rare freshwater, tidal wetland along the Virginia shoreline of the Potomac River in the Washington, D. C., area, one of the most highly-valued habitats in the region. It is one of the most significant temperate, climax, riverine, narrow-leafed, cattail marshes in the U. S. National Park system nationwide. The marsh started forming between 5,000 and 7,000 years ago with the youngest part located on the northern extension. It is unusual because much of it has survived in a large metropolitan, heavily developed area.

Habitat Loss Means Species and Opportunities Lost: Over the years, there has been a decline in many species and some have become extinct in Dyke Marsh. Dyke Marsh supports the only known nesting population of marsh wrens (Cistothorus palustris) in the upper Potomac tidal zone, a species once found in many of the marshes that lined the Potomac River. In 1950, 87 singing males were counted. In 2012, two nests were found. In 2015, one marsh wren has been seen. The least bittern, which also nests in Dyke Marsh, is on the Virginia’s threatened list. A restored Dyke Marsh can provide more habitat for more birds, fish and other wildlife, more plants, more biodiversity and more opportunities for recreation, education and scientific study.

Cleaner Water: The restoration of Dyke Marsh can help improve water quality in the Potomac River and the Chesapeake Bay because wetlands filter out pollutants and sediment loads from stormwater runoff. The Potomac provides drinking water to over five million people in the Washington area. Minimizing contaminants that might be missed during water treatment procedures can improve human health.

Restoration Can Buffer Some Flooding, Surges: Wetlands can stem flooding. A one-acre wetland can store about three acre-feet of water or one million gallons, according to the U.S. Environmental Protection Agency. (An acre-foot is one acre of land, about three-fourths the size of a football field covered with one foot of water.) Preserving and rebuilding natural defenses against storms is one of the most cost-effective and sustainable ways to protect communities and natural resources (Defenders of Wildlife). Virginia has lost almost half of its wetlands.

Rich in Diversity: Dyke Marsh has 300 known species of plants, 6,000 arthropods, 38 fish, 16 reptiles, 14 amphibians, over 230 birds. Since at least the late 1800s, it has been the only site in the upper Potomac River with a breeding population of marsh wrens, but in 2015, whether these birds bred in Dyke Marsh is unclear. The marsh has a state-threatened breeding population of least bitterns. A restored marsh can support and expand that biodiversity.

Congress Stressed Preservation: The U. S. Congress designated Dyke Marsh in 1959 by law as part of the National Park system “so that fish and wildlife development and their preservation as wetland wildlife habitat shall be paramount.” Congress reaffirmed its support and the marsh’s significance by approving House Resolution 701 in 2009 and Senate Resolution 297 in 2010. In 1974, Congress authorized the Corps of Engineers to assist NPS in restoring the “historic and ecological values of Dyke Marsh.”

Human Caused: Extensive dredging of almost half the marsh from 1940 to 1972 destabilized the marsh. People inflicted the damage; people should fix it.

When Will Dyke Marsh Be Restored?

Everyone is asking when Dyke Marsh restoration will begin and be completed?

On September 28-29, 2015, National Park Service (NPS) and U.S. Army Corps of Engineers (COE) officials met to begin the design of the restoration of Dyke Marsh under a NPS-COE interagency agreement.  Officials estimate the design phase will take at least 12 months. Once the design is completed, NPS will have to get several permits before starting construction of the first phase, the breakwater on the southern end of the marsh to replicate the promontory removed by the dredgers.   Once NPS obtains necessary permits, construction will take around two years. 

In December 2015, the Corps of Engineers created a website for the project:  http://www.nab.usace.army.mil/Missions/CivilWorks/dykemarshrestoration.aspx.  COE  has posted some history, facts, a map, photographs, tentative schedule and the conceptual restoration plan.

COE officials have said that they hope to award a contract to build the promontory in 2017 and that they might start building a containment cell in 2017 as well.  COE officials also expect substantial construction to be completed in 2019, depending on funds.

In early 2016, Corps staff conducted a bathymetric survey in Dyke Marsh (photo, right by Ed Eder).

In May, using a barge (photo left by Ned Stone), the Corps staff conducted dilatometer tests in Dyke Marsh to measure different layers of soil and soil strength for building the foundation of the breakwater in the south marsh. Building a breakwater is expected to be phase one of the marsh restoration project. These tests will inform the final design of the restoration.

In July 2016, NPS signed an agreement on restoration design with the U.S. Army Corps of Engineers and in September, NPS had a “Rapid Review Team” presentation, precursor to the “Design Advisory Board,” required for projects costing over $1 million.

On March 28-30, 2017, NPS and the Baltimore District/Corps of Engineers hosted a two-day value analysis to clarify development concepts and to further refine the project plans, including the alignment of the proposed breakwater and location of off-shore sills.

On March 7, 2017, the NPS Design Advisory Board (DAB) approved the restoration project.  The DAB reviews, comments on and if found sufficient, recommends construction projects costing over $500,000.

On May 21, 2017, the George Washington Memorial Parkway office of the National Park Service submitted a joint permit application to the U.S. Army Corps of Engineers, Norfolk District.

Dyke Marsh Restoration, A Chronology

1930s - Smoot Sand and Gravel acquired 650 acres of Dyke Marsh from Bucknell University.

1940 to 1972 - Smoot Sand and Gravel dredged least 270 acres of sand and gravel and the swamp forest wetlands of the promontory on the south end of Dyke Marsh and built the Haul Road.

1959 - Congress passed and the President Dwight D. Eisenhower signed into law P.L. 86-41 on June 11, a bill adding the Dyke Marsh Wildlife Preserve to the National Park system "so that fish and wildlife development and their preservation as wetland wildlife habitat shall be paramount." Congressman John Dingell (D-Michigan), one of the authors of the legislation, stated, "We expect that the Secretary will provide for the deposition of silt and waste from the dredging operations in such a way as to encourage the restoration of the marsh at the earliest possible moment."

1974 - Congress passed and the President signed P.L. 93-251 which authorized the U.S. Army Corps of Engineers to assist NPS in planning, designing and implementing the restoration of the “historic and ecological values of Dyke Marsh.”

1975 - Smoot Sand and Gravel relinquished their mining rights.

1977 - The National Park Service prepared an environmental assessment proposing management options for Dyke Marsh, including "attempt re-establishment of portions of the dredged marsh."

2004 - The University of Maryland, Center for Environmental Science, Appalachian Laboratory held a workshop titled, "Should We Restore Dyke Marsh"?

2007 - Congress passed the Water Resources Development Act which directed NPS to restore Dyke Marsh.

2009 - The U.S. House of Representatives approved H. Res. 701, introduced by Congressman Jim Moran (D-VA), recognizing Dyke Marsh as a unique and precious ecosystem that should be conserved, protected and restored.

2010 -The U.S. Senate approved S. Res. 297, introduced by Senator Jim Webb (D-VA), recognizing Dyke Marsh as a unique and precious ecosystem that should be conserved, protected and restored.

2010 - The U.S. Geological Survey study found that Dyke Marsh will disappear in 20 to 30 years without action. Analysis of the Deconstruction of Dyke Marsh, George Washington Memorial Parkway, Virginia: Progression, Geologic and Manmade Causes, and Effective Restoration Scenarios. By Ronald J. Litwin, Joseph P. Smoot, Milan J. Pavich, Helaine W. Markewich, Erik Oberg, Ben Helwig, Brent Steury, Vincent L. Santucci, Nancy J. Durika, Nancy B. Rybicki, Katharina M. Engelhardt, Geoffrey Sanders, Stacey Verardo, Andrew J. Elmore, and Joseph Gilmer

2013

March 27 - The Metropolitan Washington Airports Authority announced a statement of findings, making $2.5 million available to NPS for construction of the first phase of restoration a promontory in the southern part of the marsh.

October 3 - The U.S. Geological Survey published a follow-up report, concluding that ". . . Dyke Marsh presently is in its late stages of failure as a freshwater tidal marsh system . . . In the absence of human efforts to restore the equilibrium between marsh and tide, and equilibrium to the other natural forces acting on this wetland, Dyke Marsh likely will continue to accelerate its degradation, erosion, and fragmentation until it is gone. This likely will occur prior to 2035 AD." Rates and Probable Causes of Freshwater Tidal Marsh Failure, Potomac River Estuary, Northern Virginia, USA. By Ronald J. Litwin, Joseph P. Smoot, Milan J. Pavich, Erik Oberg, Brent Steury, Ben Helwig, Helaine W. Markewich, Vincent L. Santucci and Geoffrey Sanders. See the report.

October 25 - U.S. Department of Interior Secretary Sally Jewell announced the award of a $24.9 million grant to the George Washington Memorial Parkway to restore Dyke Marsh.

2014

January - NPS issued the draft Restoration and Long-term Management Plan/Draft Environmental Impact Statement and had a public comment period from January 15 to March 18. During the comment period, NPS received around 300 comments, most of which were supportive.

February 26 - NPS held a public meeting and presented the draft final environmental impact statement (EIS) and restoration plan. Around 100 people attended.

October 9 - The National Park Service published the final Dyke Marsh Restoration and Long-term Management Plan in the form of an environmental impact statement.

2015

July -- Officials of the U.S. Army Corps of Engineers (USACE) and the National Park Service (NPS) signed an interagency agreement on preparing a restoration plan.

Fall -- The U.S. Army Corps of Engineers (COE) started preparing engineering plans for restoration, after a September 28-29 "kickoff" meeting with NPS.  NPS and COE officials predict that the design phase will take 12 months.

October 15 -- The National Park Service issued a press release announcing that the COE is preparing engineering plans and that geotechnical drilling in the marsh will start on October 19.  The drilling will provide sediment samples from the marsh and help determine some features of the foundation for the design of the promontory, phase one of restoration.  The release states, " The restoration efforts are anticipated to begin summer  2017 and expected to take four years." NPS and COE announced that the "project team is looking for potential sources of clean dredged material at no cost for restoration purposes."  For information, contact Rolando Sanidad, project manager, at 410-962-2668 or This email address is being protected from spambots. You need JavaScript enabled to view it..

Once the design work is completed, NPS will have to get several permits.

The U.S. Army Corps of Engineers signed the programmatic agreement for section 106 of the National Historic Preservation Act.

December -- The Baltimore District Corps of Engineers created a website on Dyke Marsh restoration at http://www.nab.usace.army.mil/Missions/CivilWorks/dykemarshrestoration.aspx .

2016

February - The COE conducted a bathymetric survey in Dyke Marsh.

May - The COE conducted dilatometer tests in Dyke Marsh to measure different layers of soil and the soil strength for building the foundation of the breakwater in the south marsh.

June 29 – Robert Vogel, Regional Director, National Capital Region, National Park Service, signed the record of decision for the Dyke Marsh Wetland Restoration and Long-term Management Plan/Environmental Impact Statement.

July – NPS signed an agreement on restoration design with the U.S. Army Corps of Engineers.

September – NPS had a rapid review team presentation, precursor to the design advisory board, required for projects costing over $1 million.

2017

March 28-30 - NPS and the Baltimore District/COE hosted a two-day value analysis to clarify development concepts and refine the projects plans.

March 7 - The NPS Design Advisory Board (DAB) approved the restoration project. 

May 21 – The NPS submitted a joint permit application to the U.S. Army Corps of Engineers, Norfolk District.

September 12 -- On a five to zero vote, the Fairfax County Wetlands Board approved the National Park Service's restoration permit application.

September 30 – The Baltimore District of the U.S. Army Corps of Engineers awarded a construction contract to Coastal Design and Construction, Gloucester, Virginia

2018

March 27 – The Virginia Marine Resources Commission on a five to two vote approved a permit, with conditions, to build a breakwater and begin limited wetlands restoration.

July -- Coastal Design and Construction Inc., a Gloucester, Virginia, business, under contract with the U.S. Army Corps of Engineers, Baltimore District, started construction of the breakwater (photo at right).

2019

February - By February 11, Coastal Design and Construction had lowered 3,800 mattresses from a barge to the river bottom (using crane, photo at right), stacked them one on top of another and placed armor stone on top.

March 1 to July 1 - The contractor temporarily suspended work because construction permits have seasonal limitations to protect fish, birds and other wildlife during their breeding and migration season.

May 28 – The Virginia Marine Resources Commission approved a permit modification authorizing the National Park Service to start phase two of restoration, a rock sill north of the breakwater with windows to allow for tidal flushing.

September - The contractor started phase 2 of restoration, construction of a sill north of the breakwater.

2020

February - The contractor completed construction of the breakwater and sill.

2021

June 22 - The Virginia Marine Resources Commission unanimously approved a permit to extend the sill by 1,720 linear feet.

2022

November - Coastal Design and Construction completed the construction of additional sills north of the breakwater.

Map and Directions

From Alexandria, Virginia

Travel south from Old Town, Alexandria on the George Washington Memorial Parkway towards Mt. Vernon. After crossing the stone bridge at Hunting Creek (unmarked), take your next left at "Belle Haven Park & Marina/Dyke Marsh Wildlife Preserve." For parking, after turning east from the parkway, take the first left to the Belle Haven Park parking lot. The south or first lot is closest to the Haul Road Trail. The trail out to the marsh is beyond the bike path, on the right, but be sure to scan the cove in front of the picnic area for waterfowl and eagles. The Sunday morning walks meet at 8 a.m. in the south parking lot of the Belle Haven picnic area. (See the "P" in the map below.) Walks are led by experienced birders and all are welcome. Many other walks and activites meet at the Haul Road entrance. (See the yellow arrow in the map below.) The Haul Road is a dirt/gravel road or path, shown by a green dashed line on the map, which leads out into the marsh and river. 

How to Visit the Preserve without a Vehicle:

You can visit Dyke Marsh Wildlife Preserve without a vehicle by taking a 10-minute bus ride from Huntington Metro Station. Take the Fairfax Connector bus 101, 151 or 152. Go to the Fairfax Connector website for the schedule.

Get off the bus at Belle View Boulevard and Wakefield Drive across from the Belle View Shopping Center. Walk east on Belle View Boulevard about three blocks to the George Washington Memorial Parkway. Cross the parkway and walk north about 1/3 of a mile to the Dyke Marsh Wildlife Preserve sign and turn right or east on the entrance road. The pedestrian entrance to the wetland is a dirt/gravel road called Haul Road on the right at the sign marked Dyke Marsh Wildlife Habitat. (See map below.)

Mission