Photos by FODMers Included in Virginia Wildlife's Photography Showcase Magazine

Restoring Biodiversity -- the Native Plant Site

Thanks to over 40 volunteers, National Park Service staff, three grants and many generous donors, in 2018 and 2019, the Friends of Dyke Marsh and partners cleared this .065-acre area and planted over 4,000 native trees and plants, a project designed restore degraded habitat and support native wildlife. We estimate that around 80 percent of the plants and trees have survived.

porcelain  porcelain berry   Bare1
Porcelainberry (Ampelopsis brevipedunculatais rampant all along the Haul Road and outcompetes many valuable native plants.  
All photos by Glenda Booth unless otherwise noted.
  The National Park Service and FODM created a demonstration plat, clearing the area of a massive invasive plant infestation.
planting16a   planting21a

On October 4, 2018, volunteers planted around 300 native plants.  Photo by Ned Stone

  On October 11, 2019, FODM volunteers and National Park Service staff put in 400 more native plants.
Photo by Robert Veltkamp

Here are some examples of the plants you can see much of the year: Hairy leafcup or bear’s foot (Smallanthus uvedalia); riverbank wild rye (Elymus riparius); New York ironweed (Vernonia noveboracensis); deer tongue (Dichanthelium clandestinum (syn. Panicum clandestinum); Joe Pye weed (Eutrochium purpureum); common milkweed (Asclepias syriaca) and common elderberry (Sambucus canadensis).  Some native plants have naturally returned, like pokeweed (Phytolacca americana) and yellow passion flower (Passiflora lutea).

YELLOW PASSION FLOWER Passiflora lutea su kim   ironweed   bear's foot
A very welcomed surprise was the return of the yellow passion flower (Passiflora lutea) from the seed bank. Photo by Su Kim   The ironweed (Vernonia gigantea) that we planted has done well.

  An eastern tiger swallowtail butterfly (Pterourus glucus) nectars on a bear's foot/hairy leafcup (Smallanthus uvedalius) plant. 
Joe pye weed 6 ft tall Eupatoriadelphus fistulosus plants thrive in the summer gb sm2   Pokeweed plants Phytolacca americana have berries that turn dark purple in the fall gb sm2
Six-foot tall Joe-pye weed (Eupatoriadelphus fistulosus) plants thrive in the summer.   Pokeweed plants (Phytolacca americana) have berries that turn dark purple in the fall.

Why Plant Native Plants?

“Plants and animals evolve together to create unique natural communities, weaving a complex web of interrelationships,” according to the Virginia Department of Conservation and Recreation.  

Native plants which produce nectar, pollen and seeds, serve as food for native birds, butterflies, bees and other wildlife. Many insects, like butterflies, depend on specific plants, called “host plants,” with which they co-evolved for their food and shelter.

Carolina Chickadee
(Parus carolinensis) with

a caterpillar.

Here is one example of the importance of native plants to wildlife. At FODM’s September 2018 meeting, Dr. Desiree Narango, a University of Massachusetts ecologist, explained that native plants support a higher abundance and biomass of caterpillars than non-native plants. She said that a chickadee pair with four to seven young, needs between 390 to 570 caterpillars every day to feed their young. Caterpillars are very dependent on certain host plants.

Native plants can improve ecological functionality of landscapes and provide ecological services like habitat creation, stormwater retention, cleaner air and erosion and sediment control. Native plants can improve soil health. Healthy habitats have plants and animals (producers and consumers) in balance. A diversity of plants can help keep pest populations in check.

By installing and supporting native plants, this project is one small way we can restore and sustain biodiversity, strengthen the resource base for wildlife and for people and create a healthier environment.  


Partners, Grants

Our partners in this project are the National Park Service, Earth Sangha and the Audubon Society of Northern Virginia. FODM received grants from the Audubon Society of Northern Virginia, the National Environmental Education Foundation and Transurban, operator of the I-95 and I-495 express lanes, and donations from many generous members.

Controlling Invasive Plants

invasives mara surovell  
Mara Surovell helped control invasive mile-a-minute (Persicaria perfoliata).  

For many years, volunteers have diligently worked in the preserve to eliminate and control invasive species, such as stiltgrass (Microstegium vimineum), mile-a-minute (Persicaria perfoliata), porcelainberry (Ampelopsis brevipedunculata), English ivy (Hedera helix) and others.

Invasive plants are introduced intentionally or accidentally by people in a region in which they did not evolve. Invasives typically grow and spread rapidly and are prolific seed producers. They typically outcompete and displace native plants and have few controls to keep them in check. University of Delaware entomologist Douglas Tallamy offers this in his book, Bringing Nature Home: “When a plant is transported to an area of the world that contains plants, animals and diseases with which it has never before interacted, the coevolutionary constraints that kept it in check at home are gone, as are the ecological links that made that plant a contributing member of its ecosystem.”  

We welcome volunteers and can train you to identify around five target invasive plants and the control methods. To help, check the left column of our homepage,, under “Coming Events, for a link to register to help on specific dates and for more information on forthcoming events. You can also send an email to This email address is being protected from spambots. You need JavaScript enabled to view it. with any questions. 

To learn about common invasive plants in the Washington, see “Plant Invaders of Mid-Atlantic Natural Areas” at

For more information on native plants, visit Plant NOVA Natives at and the Virginia Native Plant Society at


Bittersweet   Ballard invasive vine sculpture
Oriental bittersweet (Celastrus orbiculatus) is an invasive vine that can climb and girdle trees up to the canopy level and form thick masses over shrubs and plants producing dense shade that kills them.   Austen Ballard made “invasive vine sculpture” with porcelain berry (left) and Oriental bittersweet (right). These vines were about three inches thick. Porcelain berry is a vigorous invader that blankets plants and kills them by blocking sunlight.
Austen Ballard Jim Gearing the FODM leader and Mireya Stirzaker invasive plant specialist with the GWM Parkway   FODM invasives coordinator Jim Gearing conquered an impressive invasive Oriental bittersweet vine pictured here with GW Memorial Parkway Superintendent Charles Cuvelier
Austen Ballard, Jim Gearing (the FODM leader) and Mireya Stirzaker, invasive plant specialist, with the GWM Parkway, National Park Service, are stalwarts.   FODM invasives coordinator Jim Gearing conquered an impressive, invasive Oriental bittersweet vine, pictured here with GW Memorial Parkway Superintendent Charles Cuvelier.
Austen Ballard and many others removed ivy from trees   English Ivy   AnnaMedema
Austen Ballard and many others removed English ivy (Hedera helixfrom trees.   English ivy (Hedera helix) can eventually kill trees.   Anna Medema, a National Park Service intern, helped save a tree.

Resource Materials

To help people learn more about Dyke Marsh, FODM offers some materials to enhance your visits. You may wish to print them at home before you go.

1.  Seasonal Brochures - FODM has produced four seasonal brochures to show you what is possible to see in Dyke Marsh at each time of the year. Click the links below to display and/or print each one.


2.  Dyke Marsh Birds Checklist - Birds are by far the most numerous and easily observed marsh dwellers. Their variety and numbers are astounding, especially since the return of sub-aquatic vegetation that has paralleled recent improvements in Potomac River quality. Presented here are 225 of the more common ones with their seasonal abundance and breeding data. Please go to our Facebook page where you can read reports of birds recently seen at Dyke Marsh.


3.  Mammals Seen in 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. The table below 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.


4.  Checklist of the Butterflies of the Dyke Marsh Wildlife Preserve - Butterflies delight us with their grace and beauty, while playing an essential role in pollinating a broad range of plants. Of the 90-some butterfly species found in Northern Virginia, nearly half have been reported at Dyke Marsh. With this checklist, a field guide and possibly binoculars, a few walks along the trails and boardwalks of Dyke Marsh can start to familiarize you with the most common butterflies. The listed host plants reflect the food and larval preferences of the butterfly species.


5.  Dyke Marsh Scavenger Hunt (for youngsters) - With this guide your youngsters can search for a variety of items found in Dyke Marsh.


How to Volunteer and Help

Share Your Talents


Current Opportunities to Help

The Friends of Dyke Marsh welcome the help of everyone, efforts big and small. We hope you will help us preserve and restore the Dyke Marsh Wildlife Preserve. Everyone’s efforts make a difference.

If you wish to participate, please send an email to This email address is being protected from spambots. You need JavaScript enabled to view it. and indicate how you would like to help. We will put you on a list for the activities you volunteer for and send you an email as opportunities arise.

We need help in the following areas, but feel free to indicate other ways you would like to contribute:

  • controlling invasive plants
  • planting native plants
  • helping with trash cleanups
  • staffing tables at FODM and community events
  • testing water in streams that feed into Dyke Marsh
  • helping with school groups (with other volunteers)
  • contributing articles for the Marsh Wren (newsletter) or website. What subject?
  • planning programs and meetings; bringing refreshments
  • planning and leading nature walks (Do you have a particular expertise?)
  • providing photographs for our website and publications
  • adding photographs in Facebook and Instagram posts
  • conducting research:
    ____(1) scientific
    ____(2) issues
    ____ (3) other
  • designing print materials
  • updating, maintaiining and operating our website and online membership systems
  • raising funds
  • hosting a fund raiser or other event
  • meeting with elected and other officials

Help Tackle Invasive Plants

Join FODMers 10 a.m. to noon on

  • September 23
    10 a.m. to noon
  • October 7 and 21
  • November 4 and 18
  • December 2 and 16

Nancy Herman

Nancy Herrman is a dedicated invasive plant volunteer.

Help protect native plants by pulling and clipping invasive plants. We will train volunteers to identify the five or so target plants. Click here to register to join us in any of these sessions. We kindly ask that you not bring pets. Invasive plants can threaten and outcompete native plants.

Bring gloves, hand clippers and water. We will supply instructions, examples and trash bags Wear long sleeves and pants and sun protection. We will have some tools to share. We will cancel if lightning or severe storms are anticipated.

Meet at the Haul Road trail entrance bench.

Haul Road Trail directions and parking: GPS coordinates: 38.777739, -77.050540 South of Alexandria off the GW Memorial Parkway at the sign for Dyke Marsh Nature Preserve and Belle Haven Marina, turn east onto the road toward the Potomac River. Take the first left and park in the Belle Haven Park lot. Walk back to the marina road and turn east, toward the river. Walk 30 yards. On your right is a Dyke Marsh sign and the entrance to the Haul Road trail.

Weed Warrior Training: Controlling Invasive Plants

matt and porcelainberry2 sm

The National Park Service, George Washington Memorial Parkway, is offering training sessions on controlling invasive plants this summer.

If you are interested in taking in-person training specifically for removing English ivy, register here to be added to a mailing list and receive notifications regarding future training dates.

Spotted Lanternfly Alert

Spotted Lanternfly NPS small
Spotted lanternfly
(Lycorma delicatula)
Photo by NPS

The National Park Service (NPS) asks that everyone be on the lookout for an invasive insect called the spotted lanternfly (Lycorma delicatula). As of February 3, 2023, there have been no reports of these insects on the GW Memorial Parkway properties, but the insect has been documented in Fairfax County.  Please be on the lookout for their egg masses on trees and other smooth surfaces (including rocks and vehicles) from now through spring. Egg masses look like smears of mud or mortar. NPS asks that if you see one, try to scrape it off and put it into a baggie with some rubbing alcohol or hand sanitizer.

The insect can be very destructive to trees.

There is more information in an article by a NPS official here.

For information in another article by the US Department of Agriculture click here.

Help Stop the Spread of a New Species of Water Chestnut


Water chestnut. Photo from MISC, Maryland Invasive Species Council

Be on the lookout for a new species of water chestnut (genus Trapa) ( / iotm/june-2018/) found in the Potomac watershed, Trapa bispinosa Roxb. var. iinumai Nakano.  It has been spreading since 1995 and is floating aquatic vegetation growing over the surface of a pond, lake or other fresh waterbody.

This species is identified by the seed cases having two spines instead of four found on Trapa natans. Report all invasive aquatic species to  the US Geological Survey’s Nonindigenous aquatic species website ( / SightingReport.aspx).

Water chestnut (an annual) sprouts in May, spreads over the water surface and then flowers and fruits by July.  It drops seeds all season until it senesces after a hard frost. To stop the spread, management by harvesting the plants by early July is very successful in eradicating the plants, but it may take several years of effort, if some seeds fall before the plants are harvested or lay dormant in the current year and sprout in a later year.






Restoring Biodiversity with Native Plants

 Starting in 2017 and again in 2018, in partnership with the National Park Service, the Friends of Dyke Marsh began to control invasive plants on a .065-acre area on the west side of the Haul Road trail and planted over 4,000 native trees and plants to restore the land to a healthier, more natural state.  Over 40 dedicated volunteers and National Park Service staff planted the trees and plants.  We received several grants and many generous donations (see below). Our goal is to restore a very degraded habitat.  We estimate that around 80 percent of the plants and trees have survived.

PorcelainberryInvasive plants like porcelainberry (Ampelopsis brevipedunculata) are rampant along the Haul Road Trail. They can smother and outcompete native plants. Cleared siteNational Park Service/George Washington Memorial Parkway staff cleared the site of invasive plants like English ivy (Hedera helix L) and porcelainberry (Ampelopsis brevipedunculata). VolunteerVolunteers planted native plants. Native plantsThe blue flags designated each plant that volunteers planted. Greg and MelissaGreg Crider and Melissa Westbrook, then the GWMP horticulturalist, planted a tree.

Invasives’ Harm

Non-native or invasive plants like English ivy (Hedera helix L) and porcelainberry (Ampelopsis brevipedunculata) are well established and rampant along both sides of the trail.  Why is this a problem?

Invasive plants displace native plants.  University of Delaware entomologist Douglas Tallamy offers this in his book, Bringing Nature Home: “When a plant is transported to an area of the world that contains plants, animals and diseases with which it has never before interacted, the coevolutionary constraints that kept it in check at home are gone, as are the ecological links that made that plant a contributing member of its ecosystem.”  In short, native plants support the native wildlife with which the plants coevolved.

Why Native Plants?

“Plants and animals evolve together to create unique natural communities, weaving a complex web of interrelationships,” according to the Virginia Department of Conservation and Recreation.

Native plants that produce nectar, pollen and seeds, serve as food for native birds, butterflies, bees and other wildlife. Many insects, like butterflies, depend on specific plants, called “host plants,” with which they co-evolved for their food and shelter.  (See our butterfly and host plants checklist on this website.)

Native plantsIn 2018, we had a second round and planted more native plants. Matt BrightMatt Bright with Earth Sangha, a partner, explained the value of native plants. Paul SiegelVolunteer Paul Siegel put in a plant. PlantsIn July 2018, plants were about two to three feet tall.

Here is one example of the importance of native plants to wildlife.  At FODM’s September 2018 meeting, Dr. Desiree Narango, a University of Massachusetts ecologist, explained that native plants support a higher abundance and biomass of caterpillars than non-native plants.  She said that a chickadee with four to seven young, needs between 390 to 570 caterpillars every day to feed their young.  Therefore, caterpillars are very dependent on certain host plants.

Yellow passion flowerYellow passion flower (Passiflora lutes L) returned. Yellow passion flowerYellow passion flower (Passiflora lutes L). Yellow passion flowerYellow passion flower (Passiflora lutes L) berries in the fall. New York ironweedNew York ironweed (Vernonia noveboracensis) Hairy leaf cup/bears footHairy leaf cup/bears foot (Smallanthus uvedalia)

Native plants can improve ecological functionality of landscapes and provide ecological services like stormwater retention, cleaner air and erosion and sediment control.  Native plants can improve soil health.  Healthy habitats have plants and animals (producers and consumers) in balance. Increasing diversity of plants can help keep pest populations in check.

Joe Pye weedJoe Pye weed (Eutrochium purpureum) PokeweedPokeweed (Phytolacca americana) berries Common box turtleA young common box turtle (Terrapene carolina) was at home on the site.

By trying to control invasive plants and support more native plants, this project is one small way we can restore lost biodiversity, strengthen the resource base for wildlife and for people and create a more robust environment.

Controlling Invasive Plants

Since 2018, volunteer teams have diligently worked to pull up and root out invasive species, such as stiltgrass (Microstegium vimineum), mile-a-minute (Persicaria perfoliata), porcelainberry (Ampelopsis brevipedunculata), English ivy and others.  This is an ongoing effort.

We try to have several sessions a month from May to October.  In the winter, we work on controlling English ivy in multiple places.   We train volunteers to identify about five targeted invasive plants and in the methods for controlling them.  To join us, email This email address is being protected from spambots. You need JavaScript enabled to view it. with “Invasives” in the subject line and check our homepage for forthcoming events. 

To learn about common invasive plants in the Washington, see “Plant Invaders of Mid-Atlantic Natural Areas” at

For more information on Northern Virginia’s native plants, visit Plant NOVA Natives at and the Virginia Native Plant Society at

Partners, Grants

Our partners in this project are the National Park Service, Earth Sangha and the Audubon Society of Northern Virginia.  Our efforts are also supported by grants from the Audubon Society of Northern Virginia, the National Environmental Education Foundation and the I-495/95 Express Lanes and by many generous member donors.

Thank you to Bob Veltkamp, Greg Nemetz, Bernie Krell and Colin Surovell for the sign noting the project.  Thank you to Laura Sebastianelli for initiating two Chronolog stations, one at this site, both of which we installed. We encourage visitors to take photographs at the station and send them in. To view submitted photos, visit  Put “Dyke Marsh” in the box that says Filter by Project and our two cameras will appear.

Thank you to the dedicated employees of the George Washington Memorial Parkway, National Park Service, for partnering with us on this project.

Trudi and NancyTrudi Hahn and Nancy Herrman helped remove invasive plants. Mara SurovellMara Surovell tackled mile-a-minute (Persicaria perfoliata). Jim and EdJim Gearing and Ed Eder installed the chronolog station. SpringIn the spring, plants are about one foot high. Colin and BernieColin Surovell and Bernie Krell installed a sign at the native plant site.

All photos by Glenda Booth.

Taking Action

Expressing Concerns about Widening the Mount Vernon Trail

Many trees are growing very close to the trail 2   The pumpkin ash trees that FODM Is trying to save here marked with yellow plastic tags are very close to the trail and bridge 23
Many trees are growing very close to the trail. Photos by Glenda Booth.   The pumpkin ash trees that FODM Is trying to save, here marked with yellow plastic tags, are very close to the trail and bridge 23.
Barn swallow Hirundo rustica pair built a nest under bridge 23 Photo by Todd Kiraly med
A barn swallow (Hirundo rustica) pair built a nest under bridge 23 and raised at least four young in July and August 2023. Photo by Todd Kiraly

On August 21, 2023, FODM submitted the following comments to the National Park Service on their July 2023 Asessment of Effects report.

Thank you for the opportunity to provide comments on the July 2023 Assessment of Effects Report, George Washington Memorial Parkway South Section and the Mount Vernon Trail.

We realize that this phase of the plan focuses on impacts on historic and cultural resources. We hope you have reached out to historic preservation officials in Virginia, Fairfax County, Arlington and Alexandria as well as private groups like the Mount Vernon Ladies Association, the American Horticultural Society (River Farm), Mount Vernon Regional Historical Society and the Friends of Fairfax Archaeology and Cultural Resources.

We are pleased that the parkway will not be wider than its current footprint and urge you to maintain its historic character.

We agree with your goal to “not diminish the significance or integrity of the historic property” (page 29). We hope you will consult with FODM on your plans, especially if designs will have adverse environmental impacts.

We filed extensive comments on January 16, 2023, and direct you to those in making your final plans. Our views have not changed. (These comments appear below the next section on this web page.)

We oppose increasing impervious surfaces, harming and destroying mature native trees and native plants; staging construction in the preserve without restoring habitat; and other adverse impacts to an already fragile and diminishing wetland complex.

Our recommendations:

(1)    We recommend that you acknowledge (e.g., page 2, page 8, page 19) that the trail is used by many people to observe and study nature; conduct plant, bird and other surveys; host walks; conduct outdoor programs; conduct academic research and other non-recreational purposes. Those uses should be given equal weight in your plans. In describing trail users on page 19, these uses are ignored or omitted.

To base widening the trail on recommendations by American Association of State Highway and Transportation Officials (AASHTO) appears to focus solely on transportation, not the multi-, non-transportation uses we describe above, which are equally and perhaps more important in light of the rarity of the wetlands in the NPS system and challenges in Dyke Marsh, including the decline in biodiversity, native plants, birds, insects and other natural resource degradation.

Naturalists, students, academics, historians and others use the trail, especially bridge 23, for their studies and surveys. It is a prime area for viewing marsh habitat, tidal activity and wildlife.

(2)    We question the need to widen the multi-use trail to 10 feet from the current 8 to 9 feet south of Alexandria (page 27) and continue to request a bicycling safety study as we previously recommended. We assume that “safety improvements,” one of the bases of this plan, are supported by documented unsafe conditions. We again ask that you analyze and make publicly available the current state of safe use of the trail by all users, especially bicyclists.  

More impervious surface (which your plan acknowledges) can harm and kill trees and other vegetation, introduce more disturbances and invasive plants, increase stormwater runoff, increase human-wildlife conflict, wildlife deaths and further degrade Dyke Marsh.

(3)    As expressed on pages 7 and 16, NPS plans to rehabilitate the bridge over Hunting Creek. We believe NPS should consider designs that allow for marsh migration landward, in light of the rising river levels.

(4)    We would appreciate more detail on the page 15 statement that NPS will "conduct tree pruning and clear vegetation" at places along the trail. At a minimum, NPS should conduct a thorough tree survey as mentioned on page 27, document what trees are present and avoid further harm to trees and prepare a biological inventory of plants and animals present. The plan should include planting more trees, beyond those impacted by these plans. The parkway is losing many valuable trees. Dyke Marsh alone is losing over 1,000 pumpkin ash trees.

(5)    The changes to the Belle Haven marina road appear largely to address crosswalks and the left turn from the parkway into the driveway (pages 9-10). Improving crosswalks and turns off the parkway could make Dyke Marsh visitors’ access more accessible and safer.  

(6)    On page 15, NPS plans to build a new "comfort station" at Gravelly Point and make amenity improvements along the trail (benches, drinking water, racks for bikes). We continue to urge upgrading the restrooms at Belle Haven Park and make them available in all seasons.

(7)    We urge that any drainage and stormwater management changes (pages 28-29) not send more polluted stormwater into Dyke Marsh or the Potomac River. We urge NPS to retain more stormwater onsite and to convince Fairfax County and other jurisdictions to implement measures that retain more stormwater onsite, to prevent it from flowing into the marsh and river. NPS should mitigate any adverse impacts of expanding impervious surfaces.

Since the trail is located in a wetland and floodplain at many points, ponding (page 29) and flooding are inevitable. NPS and trail users should live with it.

Commenting on the U.S. Army Corps of Engineers’ Proposed Belle View Floodwall and Levee, Draft Integrated Feasibility Report and Environmental Assessment (May 2022)

Floodwall Map

Provided here are the Corps of Engineers Feasibility Report and Environmental Assessment and documents related to comments provided to the U.S. Army Corps of Engineers.

1.  U.S. Army Corps of Engineers’ Feasibility Report and Environmental Assessment (Plan)

2.  Comments FODM submitted to the Corps

3.  FODM summary of all public comments

4.  All comments submitted to the Corps

Expressing Concerns about Trail Construction

Many trees are growing very close to the trail 1   Many trees are growing very close to the trail 2
Many trees are growing very close to the trail.  All photos by Glenda Booth

On December 6, 2022, the George Washington Memorial Parkway (GWM) unit of the National Park Service (NPS) published a proposed plan and environmental assessment to perform some construction on the south GWM Parkway segment and the Mount Vernon Trail. Around 2.5 miles of the trail is in the Dyke Marsh Wildlife Preserve.

On January 16, 2023, FODM submitted the following comments on the NPS’s plans. FODM's January 16 Comments

On January 18, 2023, FODM submitted the following additional comments on the NPS’s plans. FODM's January 18 Comments

The NPS proposal is posted here:

 The red pen is 5 12 inches long illustrating how close the tree trunk is to the trail   The multi use trail attracts many bikers
The red pen is 5 1/2 inches long, illustrating how close the tree trunk is to the trail.   The multi-use trail attracts many bikers.

The pumpkin ash trees that FODM Is trying to save here marked with yellow plastic tags are very close to the trail and bridge 23   Bridge 23 on the trail and in Dyke Marsh is a favorite spot for nature study
The pumpkin ash trees that FODM Is trying to save, here marked with yellow plastic tags, are very close to the trail and bridge 23.   Bridge 23 on the trail and in Dyke Marsh is a favorite spot for nature study.

Increasing Local Parks’ Resources

  Gamble1   Gamble2

On April 13, 2022, FODM Board member Carolyn Gamble testified before the Fairfax County Board of Supervisors urging these elected officials to increase funding for local parks in the fiscal year 2023 budget. She explained that county officials’ decisions and what happens in local parks affect the larger environment, including the Dyke Marsh Wildlife Preserve.

To view her statement,  click here.

Discouraging Single-use Plastics

Plastic Bags 3On September 14, 2021, FODM submitted comments to the Fairfax County Board of Supervisors supporting a proposed fee on single-use plastic bags. The Board approved the proposal which will go into effect on January 1, 2022. Below are our comments submitted to the Board.

The Friends of Dyke Marsh urge the Board of Supervisors to approve a fee on certain disposable plastic bags, as proposed in the draft ordinance.

The Friends of Dyke Marsh (FODM) is a non-profit 501(c)(3) organization dedicated to preserving, protecting and restoring the Dyke Marsh Wildlife Preserve. Dyke Marsh is a 485-acre freshwater tidal wetland complex in Fairfax County on the Virginia shoreline of  the Potomac River. The Potomac River is a major tributary of the Chesapeake Bay. Dyke Marsh is ecologically diverse, offering habitat for 300 known species of plants, 6,000 arthropods, 38 fish, 34 mammals, 16 reptiles, 14 amphibians, over 275 species of birds and at least 20,000 species of insects. 

In our numerous trash cleanup events over many years, we have frequently found plastic debris, including plastic bags and plastic bag fragments within the preserve, at Belle Haven Park and along the Potomac shoreline. The standard grocery and convenience store plastic bags are flimsy and intended for single use. We believe that most are not recycled. Even when properly disposed of, for example, placed in a trash receptacle or recycled, this plastic waste can still make its way into woodlands, vegetated areas and local waterways. We have experienced wildlife getting into trash cans searching for food and spreading trash, including plastic bags, all around.

Microplastics Cause Harm

Plastic Bags 2Plastics break down into smaller pieces called micro-plastics that infiltrate into the ecosystem and  waterways. Micro-plastics continue to break down into such small pieces that they become impossible to completely remove, even during targeted cleanup events. 

Wildlife, especially birds, turtles and fish, are particularly vulnerable to this plastic pollution. Micro-plastics are frequently ingested by wildlife: birds and fish often mistake them for food or may consume insects and worms that have ingested the plastics. Micro-plastics act as magnets for harmful pollutants and often become laden with chemicals, which are then passed along the food chain from insects and worms to birds and fish and, eventually, to humans.

In addition to the harmful chemicals, we know that when birds ingest these plastics, they can die by starvation because the plastic takes up space in their stomachs and  makes the birds feel full of a material that does not break down or provide any nutritional value.

FODM has conducted Dyke Marsh breeding bird surveys for over 27 years, which highlight the presence of plastics and how birds interact with them. During the survey conducted between May and July in 2021, we identified nearly a dozen osprey nests and three bald eagle nests within the preserve. These nests had debris, including plastic bags and bag fragments, in them. Ospreys and their young can get entangled in these plastics, which can result in fatal outcomes.

Reduce Use

Plastic Bags 1The only way to reduce the amount and harmful side effects of plastic debris in our ecosystem and local waterways is to reduce the amount of plastics produced and used. Creating ways to dispose of these plastics is only a band aid to a growing issue. Therefore, it is critical for our local, state and federal governments and elected officials to implement policy changes such as the proposed plastic bag fee.  

Fees on single-use plastic bags in other localities and states have proven to raise awareness of their harm and to reduce their use and improper disposal. Bag fees in other areas have proven to reduce plastic bag trash, for example, in Washington, D.C.

These policy changes can help shape behavior and raise public awareness through educational and volunteer opportunities that can be funded through the collected revenue.

More Revenue

According to and its July 2019 estimate, there are 1,147,532 residents living in Fairfax County. If half of these residents used one plastic bag during weekly trips to the grocery store, this would total 29,835,884 plastic bags used annually within the county – and this is a conservative estimate.

If this fee is enacted and Fairfax County residents still consume 29,835,884 plastic bags during the 2022 calendar year, at a collection rate of $0.03 per plastic bag, the county could receive $895,076.52 in revenue which the county could use to fund litter reduction and anti-littering education programs to increase public awareness of reducing environmental waste and mitigating  litter pollution.   

As Virginia Governor Ralph Northam has said, “It takes a village to be stewards of our environment and natural resources.” Enacting the proposed disposable plastic bag fee is a critical, necessary and a long overdue step for Fairfax County, our residents and importantly, our natural resources. We believe that Fairfax County’s residents want to be good stewards of the environment and to protect our precious natural resources on which we all depend.

Thank you for the opportunity to present our views and recommendations.


Stemming the Trash Flood

Trash cans, trash traps, dumpsters and storm drain gutter guards may keep some trash out of Dyke Marsh and our waterways, but the real solution to the never-ending stream of trash is to stop generating it in the first place. On October 19, 2020, Zach Huntington, Clean Streams Program Manager for Clean Fairfax (, conducted a briefing on the trash menace and possible solutions.

Solid waste collections are increasing in Northern Virginia. In fact, Fairfax County is the second largest trash collector among local jurisdictions in the United States. Republic, a company that services Fairfax County is the second largest hauler in the U.S. and their national average has increased by 30 percent this year. The county has seen a 40 percent increase in residential trash tonnage since last year and a 30 percent increase in curbside collection since the March 2020 onset of the coronavirus pandemic.

He described several litter prevention legislative solutions, including plastic bag fees, polystyrene bans, increasing litter taxes and extended producer responsibility. You can view the presentation here.

Some bills anticipated in the 2021 Virginia General Assembly are described on the Litter Free Virginia website, In addition to FODM, other organizations represented were the Porto Vecchio Waterfront Committee, the Audubon Society of Northern Virginia, Friends of Little Hunting Creek and the Friends of Accotink Creek.

GW Parkway GW Parkway GW Parkway cyclist

FODM Weighed in on GWM Parkway Safety Study

The National Park Service (NPS) is conducting a safety study of the south segment of the George Washington Memorial Parkway.  After a July 11, 2019 public meeting, NPS had a public comment period which ended on August 21.  FODM submitted the following comments. Read here.

GW Parkway GW Parkway GW Parkway cyclist

FODM on the Future of Claude Moore Farm Park, May 23, 2019

In 2019, the George Washington Memorial Parkway unit of the National Park Service is considering a concept plan for the Claude Moore Farm area of Turkey Run Park.  FODM submitted the following comments on May 23, 2019 and stressed the importance of conducting a comprehensive biological inventory of the natural resources there and preserving conservation corridors.

FODM on the Future of Claude Moore Farm Park, October 26, 2019

On October 26, 2019 FODM submitted the following comments on the National Park Service's proposed three concepts for the former Claude Moore Farm area of Turkey Run Park.

Oxon Hill Farm

On June 25, 2019, FODM wrote to the National Park Service’s (NPS) Acting Director, Mr. Dan Smith, and urged NPS not to develop Oxon Hill Cove National Park and Oxon Hill Farm, to preserve its biodiversity and not to trade it for land elsewhere. Read FODM's letter here.

Oxon Hill Farm Oxon Hill Farm

Trainings: Controlling Invasive Plants, June 15 and 18

The National Park Service, George Washington Memorial Parkway, is offering training sessions on controlling invasive plants. There will be one virtual classroom training and one in-person training for field work at two different times.

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Disfrute una Visita a Dyke Marsh

 Dyke Marsh


The Dyke Marsh Wildlife Preserve (la Reserva Natural de Pantano Dyke (pronunciado “Daik”) es un pantano de agua dulce y de marea a la ribera del Rio Potomac en Virginia.  Es una parte del George Washington Memorial Parkway, controlado por el Servicio Nacional de Parques de los EEUU.  Para más información, visite al sitio del web
El pantano está abierto y gratis a todo el mundo.  Contiene muchas diferentes plantas, y animales incluyendo pájaros, mamíferos, reptiles, peces y insectos.  En Dyke Marsh puede usted caminar un sendero de más de un kilómetro para ver la naturaleza y el rio Potomac.  Además hay una marina al lado del pantano donde puede rentar canoas y kayaks para disfrutar el coto por agua.
Para llegar a Dyke Marsh, pasen en rumbo sur de Washington DC en George Washington Memorial Parkway.  En la ciudad de Alexandria sigue directo en Washington Street al sur.  Despues de salir de la ciudad, sigue solo media milla, y verá letreros a Belle Haven Marina y Dyke Marsh Wildlife Preserve, y gire al izquierda.  Estacionarse en el Picnic Area.

peregrine falconPeregrine falcon. Photo by Ed Eder

Red slider turtleRed slider turtle. Photo by Ned Stone

Dyke Marsh es apoyado por una organización de voluntarios llamada Friends of Dyke Marsh  (Amigos del Pantano).  En el internet, explore  (escrito en inglés).  Para más información, escriba a This email address is being protected from spambots. You need JavaScript enabled to view it..


If you don't remember your user name or password and the "Forgot your password?" or "Forgot your username?" links don't work for you, send an email to This email address is being protected from spambots. You need JavaScript enabled to view it. for assistance.



Marsh Wren Honored

FODM's newsletter,The Marsh Wren received an Excellence in Craft Award as the Best Virginia Newsletter from the Virginia Outdoor Writers Association at the group's annual meeting in February, 2014. Congratulations to Dorothy McManus, Editor, and Duncan Hobart, Assistant Editor pictured below with the award.


The Marsh Wren is the quarterly newsletter published by the Friends of Dyke Marsh.  It provides the latest news on what is happening in Dyke Marsh, announcements of upcoming events and activities and other information of interest to members of FODM.  In the table below, click on the issue date to open the newsletter in PDF format.

Members must log in to view the most recent edition of the newsletter.  Send an email to This email address is being protected from spambots. You need JavaScript enabled to view it. if you need help logging in.

Birds of Dyke Marsh

green heronBirds are by far the most numerous and easily observed marsh dwellers. Their variety and numbers are astounding, especially since the return of sub-aquatic vegetation that has paralleled recent improvements in Potomac River quality. One expert, Lt. Col. Jackson M. Abbott, compiled a list from over 40 years of recorded observations of 296 species seen in Dyke Marsh. Presented here are 225 of the more common ones with their seasonal abundance and breeding data. Please go to our Facebook page where you can read reports of birds recently seen at Dyke Marsh.
Relative Abundance
a    Abundant
v    Very Common
c    Common
u    Uncommon
vu    Very Uncommon
r    Rare
vr    Very Rare
*    Confirmed Breeder
I    Irruptive Species
Print Dyke Marsh Birds Checklist You will need Adobe Acrobat Reader®. Download a FREE Reader now by clicking on the icon below.
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Red-throated Loon vr     vr Red-headed Woodpecker vr   vr vr
Common Loon u   vu vu Red-bellied Woodpecker * vc vc vc vc
Pied-billed Grebe u r c c Yellow-bellied Sapsucker     vu vu
Horned Grebe vu   vu u Downy Woodpecker * vc c vc vc
Double-crested Cormorant vc c vc vu Hairy Woodpecker * u vu u vu
American Bittern vu   vu   Northern Flicker * c c c u
Least Bittern * u u vu   Pileated Woodpecker * vu vu u vu
Great Blue Heron vc vc vc vc Eastern Wood-Pewee * c c u  
Great Egret vu u vc c Yellow-bellied Flycatcher     vr  
Snowy Egret r vu u   Acadian Flycatcher * u u vu  
Little Blue Heron     r   Willow Flycatcher * vu vu    
Tri-colored Heron vr       Eastern Phoebe * u r u r
Cattle Egret vr       Great Crested Flycatcher * vu vu vu  
Green Heron * vu vu u r Eastern Kingbird * vc vc c  
Black-crowned Night Heron r vu u r White-eyed Vireo * u vu u  
Yellow-crowned Night Heron   vr     Yellow-throated Vireo vu   r  
Glossy Ibis r       Blue-headed Vireo r      
Black Vulture vr vr r r Warbling Vireo * vc vc vc  
Turkey Vulture vu vu vu vr Philadelphia Vireo     vr  
Snow Goose     vu vr Red-eyed Vireo * vc vc u  
Canada Goose * a vc vc a Blue Jay * vc c vc c
Mute Swan vu vu r   American Crow * a a a a
Tundra Swan vu     vu Fish Crow * vc u vu c
Wood Duck * u vu u vu Purple Martin * c u c  
Gadwall r   vu vu Tree Swallow * vc vc u vr
American Wigeon r   u vu Northern Rough-winged Swallow * u vu vu  
American Black Duck * u u c vc Bank Swallow * vu   r  
Mallard * vc vc vc vc Cliff Swallow r   vu  
Blue-winged Teal r r u r Barn Swallow * a a vc  
Northern Shoveler vu   u vu Carolina Chickadee * vc vc vc vc
Northern Pintail r   c u Tufted Titmouse * vc vc vc vc
Green-winged Teal u   c u White-breasted Nuthatch u u vu vu
Canvasback r vr u vu Brown Creeper u vr r vu
Redhead     r vu Carolina Wren * vc vc vc vc
Ring-necked Duck vu vr vu vu House Wren * vu vu vu  
Greater Scaup vu vr r vu Winter Wren vu     vu
Lesser Scaup c vr vu c Marsh Wren * vc vc u  
Long-tailed Duck       vr Golden-crowned Kinglet u   u u
Bufflehead u vr u c Ruby-crowned Kinglet c   u u
Common Goldeneye     r vu Blue-gray Gnatcatcher * c c u vr
Hooded Merganser vu r vu u Eastern Bluebird vr vr   r
Common Merganser c     c Veery r      
Red-breasted Merganser c vr vu u Hermit Thrush r      
Ruddy Duck u vr c u Wood Thrush * vu vu    
Osprey * vc vc vc r American Robin * a vc vc u
Bald Eagle u r c vc Gray Catbird * vc vc vc vu
Northern Harrier vr   u vu Northern Mockingbird * vc c vc vc
Sharp-shinned Hawk vu   u vu Brown Thrasher * vu vu vu  
Cooper's Hawk vu vr r vu European Starling * a a a a
Red-shouldered Hawk u   vu u Cedar Waxwing * c u u vu
Broad-winged Hawk vu   vu   Blue-winged Warbler vu   vu  
Red-tailed Hawk vu   vu u Tennessee Warbler vr      
American Kestrel vu   vu vu Orange-crowned Warbler       vr
Merlin r   vu   Nashville Warbler     vu  
Peregrine Falcon r   vu r Northern Parula * vc u vu  
Northern Bobwhite vr vr     Yellow Warbler * vc vc c  
King Rail   vr     Chestnut-sided Warbler     vu  
Virginia Rail r       Magnolia Warbler u   u  
Sora r       Cape May Warbler r   vu  
Common Moorhen     r   Black-throated Blue Warbler u   r  
American Coot u vu u u Yellow-rumped Warbler c   c u
Black-bellied Plover     vu   Black-throated Green Warbler u   vu  
American Golden Plover     vu   Blackburnian Warbler     r  
Semipalmated Plover     u   Yellow-throated Warbler     vr  
Killdeer u vc c u Pine Warbler     vu r
American Avocet     vr   Prarie Warbler     r  
Greater Yellowlegs c vc c vu Palm Warbler     vu  
Lesser Yellowlegs vu u vc   Bay-breasted Warbler vr   r  
Solitary Sandpiper vu r vu   Blackpoll Warbler c vr    
Willet     vr   Black-and-white Warbler vu   u  
Spotted Sandpiper c vu u   American Redstart * c vu vu  
Hudsonian Godwit     vr   Prothonotary Warbler * u u vu  
Marbled Godwit     vr   Worm-eating Warbler r      
Ruddy Turnstone     vr   Ovenbird vu   r  
Red Knot     vr   Northern Waterthrush vu   r  
Sanderling     r   Louisiana Waterthrush   vr vu  
Semipalmated Sandpiper   c u   Kentucky Warbler vr      
Western Sandpiper   vu vu   Common Yellowthroat * vc vc vc r
Least Sandpiper vu c vu vr Hooded Warbler *     vr  
White-rumped Sandpiper     r   Wilson's Warbler vu   vr  
Baird's Sandpiper     vr   Canada Warbler vu   vu  
Pectoral Sandpiper vu r u   Yellow-breasted Chat vr     vr
Dunlin r   r vu Scarlet Tanager * vu vu vu  
Stilt Sandpiper   r vu   Eastern Towhee * u vu vu r
Short-billed Dowitcher   c u   American Tree Sparrow       vu
Long-billed Dowitcher   r vu r Chipping Sparrow * r vr vr  
Common Snipe vu   vu r Field Sparrow * u vu u r
Wilson's Phalarope     vr   Savannah Sparrow vu   vu r
Red-necked Phalarope     vr   Seaside Sparrow vr      
Laughing Gull u vc vc u Fox Sparrow     r vu
Franklin's Gull     vr vr Song Sparrow a vc a vc
Bonapartes's Gull - I u   vu vu Lincoln's Sparrow vr   r  
Ring-billed Gull a vc a a Swamp Sparrow * u vu u u
Herring Gull vc c vc vc White-throated Sparrow a   a a
Lesser Black-backed Gull     r r White-crowned Sparrow r   r r
Great Black-backed Gull a c vc vc Dark-eyed Junco vu   u u
Caspian Tern vc vu vc   Snow Bunting       vr
Royal Tern vr       Northern Cardinal * vc vc vc vc
Common Tern   vu vu   Rose-breasted Grosbeak vu   r  
Forster's Tern u c vc vu Blue Grosbeak vr      
Black Tern   vr r   Indigo Bunting * u vu vu  
Rock Dove * a a a vc Bobolink     r  
Mourning Dove * vc vc vc vc Red-winged Blackbird * c a a u
Black-billed Cuckoo r       Rusty Blackbird u   vu vu
Yellow-billed Cuckoo * u c c   Common Grackle * vc vc vc u
Eastern Screech Owl * vr     r Brown-headed Cowbird * vc vc u vu
Great Horned Owl * vr     r Orchard Oriole * vc vc u  
Barred Owl * vr r   r Baltimore Oriole * vc vc u  
Common Nighthawk vu   vu   Purple Finch - I vu     r
Whip-poor-will vr       House Finch * a vc vc c
Chimney Swift * vc a vc   Pine Siskin - I       r
Ruby-throated Hummingbird * u u u   American Goldfinch - I * a vc vc c
Belted Kingfisher * u u c u House Sparrow * vc vc vc c

Marsh Life

About the Marsh

Dyke Marsh InletA 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. 


Why Is Dyke Marsh Significant?

FODM has created a fact sheet that explains why Dyke Marsh is significant. It includes some of the rare plants and animals in the marsh. To view the flyer, click here.

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.

 What to See in Dyke Marsh    
 FODM has produced four seasonal brochures to show you what is possible to see in Dyke Marsh at each time of the year. Click the links to display each one.


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

studyUnder 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

  Mammals Seen in Dyke Marsh
     Virginia Oppossum (Didelphis virginiana)
     Northern Short-tailed Shrew (Blarina brevicauda)
     Eastern Mole (Scalopus aquaticus)
     Star-nosed Mole (Condylura cristata)
     Little Brown Myotis (Myotis lucifugus)
     Northern Red Bat (Lasiurus borealis)
     Hoary Bat (Lasiurus cinereus)
     Silver-haired Bat (Lasionycteris noctivagans)
     Eastern Pipistrelle (Pipistrellus subflavus)
     Big Brown Bat (Eptesicus fuscus)
     Evening Bat (Nycticeius humeralis)
     Eastern Cottontail (Sylvilagus floridanus)
     Eastern Chipmunk (Tamias striatus)
     Woodchuck (Marmota monax)
     Eastern Gray Squirrel (Sciurus carolinensis)
     Southern Flying Squirrel (Glaucomys   volans)
     American Beaver (Castor canadensis)
     Marsh Rice Rat (Oryzomys palustris)
     Eastern Harvest Mouse (Reithrodontomys humulis)
     White-footed Mouse (Peromyscus   leucopus)
     Deer Mouse (Peromyscus maniculatus)
     Eastern Woodrat (Neotoma floridana)
     House Mouse (Mus musculus)
     Norway Rat (Rattus norvegicus)
     Black Rat (Rattus rattus)
     Meadow Vole (Microtus pennsylvanicus)
     Common Muskrat (Ondatra zibethicus)
     Red Fox (Vulpes vulpes)
     Common Gray Fox (Urocyon cinereoargenteus)
     Common Raccoon (Procyon lotor)
     Mink (Mustela vison)
     Striped Skunk (Mephitis mephitis)
     Northern River Otter (Lutra canadensis)
     White-tailed Deer (Odocoileus virginianus)

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

beaversFODMer 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

Dyke Marsh westFODM 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:

Little brown bat■  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.)


least bitternLeast bittern (Ixobrychus exilis). Photo by Ed Eder.Scarlet tanagerScarlet 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

Screech owlEastern screech owl (Megascops Asia). Photo by Ed Eder.

Barred owlBarred 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

swallowtailEastern tiger swallowtail (Papilo glaucus). Photo by Glenda BoothMonarchMonarch 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 skimmerTwelve-spotted skimmer (Libellula pulchella). Photo by Kevin MunroeRusset-tipped clubtailRusset-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 swallotailEastern 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

reddragonThe 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.).

amberwingMale 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.

bigbluetBig 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 cattailNarrowleaf 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

Dr. WellsOn 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. 


Swamp rose mallowSwamp dogwoodThe 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.

Wild grapeSwamp milkweed


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 sumacPickerelweedSmooth 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.


Groundnut vineWater hemlockThe 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.

Tall coneflower


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

BobSmithRobert 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

AdamLizardo 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.

PumpkinAshFour 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.”

              pumpkinashFODMers 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.

Robert SmithRobert Smith manages the pumpkin ash restoration project for FODM.

deadtreesThe marsh has many dead trees, presumably killed by the invasive emerald ash borer.

Lizardo Bonilla-TezaLizardo Bonilla-Teza of Bartlett Tree Experts measures a tree that has beaver-protection wire around it.

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

PumpkinAshThis 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 BoothtunnelshClose-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.


                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 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 and

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

by Glenda C. Booth

Marsh WrenMarsh Wren (Cistothorus palustrus)
Photo by Ed Eder
It’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.”

 Students Produce Video about Dyke Marsh

by Cece Brower

From April to June, 2015, I had a English-history-chemistry assignment at Thomas Jefferson (TJ) High School for Science and Technology to create a documentary about a local environmental issue involving chemistry. My group chose to address the restoration of the Dyke Marsh wetland because it's an important project that affects our community and the health of the Potomac River. We thought it would be interesting to make our documentary child friendly, so we chose to use a puppet approach.

The other students who worked on it were Leela Ramineni, Ragavi Murali and Tatiana Bennett. We were all sophomores at TJ when we did the project. Tatiana now goes to Stone Ridge School.

Raptor Rapture

KidsChildren enjoyed interactive participation at the Earth Day event on April 20. Photo by Ed Eder.Around 300 people came out on April 20 to learn about raptors.

To celebrate Earth Day, the Friends of Dyke Marsh, the Monarch Teacher Network, the National Park Service and the Raptor Conservancy of Virginia (RCV) set up an exhibit in Belle Haven Park raptorYoungsters of all ages were captivated by the display of raptors. Photo by G. Booth.from 10 a.m. to 12 noon near the bicycle path.

Kent Knowles and Gabby Hrycyshyn of RCV introduced visitors to birds of prey – a barred owl, an Eastern screech owl, a peregrine falcon hybrid, a red-shouldered hawk and a red-tailed hawk. RCV rehabilitates injured raptors and then releases those that can survive on their own.

For more information on their work, visit their website

Through conservation and education, FODM works to support raptors and other wildlife and their habitat.

2015 Frog Survey and Frog Calls

toadAmerican toad (Anaxyrus americanus)Laura Sebastianelli led the first known citizen monitoring program in Dyke Marsh West from March to August after launching our own FrogWatch USA chapter early in 2015.  She heard and documented six species.  "The songs of spring peepers, American toads and especially green tree frogs were pleasant surprises," she wrote in our fall newsletter, The Marsh Wren.

SurveyorstreefrogGray tree frog (Hyla versicolor) and Cope's Gray Tree Frog (Hyla chrysoscelis) look identical but can be differentiated by their call. focused on Dyke Marsh West because some River Towers Condominiums residents expressed concerns about what appeared to be declining frog species over the past several years.  They said, for example, that they still heard bullfrogs and green frogs, but they no longer heard spring peepers, American toads, wood frogs or gray tree frogs. Experts say it is not unusual for amphibian populations to rise and fall.  Worldwide, scientists have documented an overall decline.

Laura shared these observations:  "Beginning in early April, I heard a lone spring peeper frequently on the grounds of River Towers Condos for over a month. While I heard only one voice calling from the same location, not far away, in Belleview Elementary School's wetland meadow, a small chorus of spring peepers began calling in late March. Their songs carry a significant distance and combined with the knowledge that peepers have been documented to migrate up to two miles for breeding, the song of the lone spring peeper at River Towers became a song of hope. Describing the sound of spring peepers in years past as 'delightfully deafening,' residents had not recalled hearing a spring peeper in at least three years. In May, we regularly heard a lone American toad for weeks. bullfrogAmerican bullfrog (Lithobates catesbeianus)In June, we documented a gray tree frog. These were welcomed songs that most people have not heard for at least three years.  While focused on Dyke Marsh West, the surprise of the season was Ed Eder's hearing a green tree frog near the Haul Road, not part of our 2015 study area." 

Volunteers Identify 16 Herptofauna, Two New Species in DMWP

search2Matthew Neff and Alonso Abugattas search for herps. Photo by Greg Crider.NicoleCharles Smith (looking at a field guide to correctly identify the turtle), and Nicole Reintsma is holding the turtle she found. Photo by Greg Crider.Forty enthusiastic volunteers conducted a herpetology survey in the Dyke Marsh Wildlife Preserve on May 3, 2012, an effort sponsored by the Virginia Herpetological Society, the Friends of Dyke Marsh and the U.S. National Park Service (NPS). Herpetology, a branch of zoology, is the study of amphibians (like frogs, toads, salamanders and newts) and reptiles (like snakes, lizards, turtles and terrapins). Herpetology is derived from Greek words meaning the “knowledge of crawling things.” Volunteers looked under logs and rocks, poked in the leaf litter and searched through brush piles. Some herpers explored the flotsam and trash along the shoreline.

By day’s end, the group had identified 16 species. “The May 3 effort added two new records, the non-native yellow-bellied slider and eastern king snake,” concluded NPS’s Brent Steury, Natural Resources Program Worm SnakeWorm Snake (Carphophis amoenus) about 10 inches long. Photo by Greg Crider.Manager for the George Washington Memorial Parkway. “Any time we add a new species, especially a vertebrate to the thousands of species previously recorded from the George Washington Memorial Parkway, we add a missing piece to the puzzle of biological diversity that exists in Northern Virginia.” Alonso Abugattas, Manager of Arlington’s Long Branch Nature Center, commented, “The information is important for the park and its managers because you can't protect or manage what you don't know you have or what's in trouble.” The survey had three segments: 10 a.m. to 1 p.m. on land, in four different areas; 2 to 5 p.m. on water; and 8 to 9:15 p.m. on land to listen for frogs calling.

Click here to read the survey report by the survey's leader, Caroline Seitz.

Research on Sediment Dynamics in Dyke Marsh

Many of us have wondered, "Is the marsh growing or shrinking? Is it being rebuilt by the river, or are we losing it to erosion?" To provide some answers to these questions, research in the gain and loss of sediments in the marsh has been undertaken by Cindy Palinkas and David Walters of the Horn Point Laboratory of the University of Maryland Center for Environmental Science in Cambridge, MD, in cooperation with the National Park Service, building on earlier work by Katia Engelhardt. They reported their work in a poster paper at a recent conference of the American Geophysical Union. The goal of their study is more modest than predicting the ultimate fate of the marsh: "to better understand the spatial and temporal variability in sedimentary processes in a freshwater tidal marsh." There are competing effects at work in setting the level of the marsh relative to the river. The Potomac always carries a burden of sediment, which is greatly enhanced following heavy rain upstream. Two daily incoming tides flood parts of the marsh, and some of the river-borne sediment is left behind in those areas.

Surface Elevation TableA Surface Elevation Table used to evaluate gain or loss of sediments. Photo by Ned Stone.Some weather conditions can produce unusually high water levels, bringing sediments onto higher ground. On the other hand, heavy rain in the local area can produce strong outflows, and will wash some of this sediment back out. Also working against building up the marsh are two long-term effects: sea level rise and the general subsidence of the entire Maryland-Virginia area. Several different techniques are involved in evaluating the gain or loss of sediments. One, deployed by the National Park Service, is called a SET (Surface Elevation Table) (see photo). Researchers have installed a dozen of these in the marsh in the last decade. Other techniques involve collecting deposits on ceramic tiles and radioisotope sampling as a function of depth. These measurements were made at approximately 24 sites in locations throughout the marsh. Results on several time scales - month, season, year, and decade - are presented in the paper. This research by Palinkas and Walters is not yet complete. Also, the sediment results vary considerably from place to place in the marsh. For those reasons, it is not yet possible to draw any firm conclusions about gain and loss over the whole marsh. Reading their report, however, suggests that while the marsh is generally gaining in deposited sediments, it may nonetheless be losing to subsidence.

Learn More About DMWP’s Complex Biodiversity

barrows2Dr. Edd Barrows leads students in study along Haul Road in Dyke Marsh. Photo by Robert Smith. An excellent website for learning about the many natural resources of Dyke Marsh Wildlife Preserve (DMWP) is the Biodiversity Database of the Washington, D.C., Area (BDWA), produced by Professor Dan Kjar of Elmira College and Professor Edd Barrows of Georgetown University’s Laboratory of Entomology and Biodiversity. The BDWA has arthropod lists and photographs of many DMWP organisms, provides
helpful links and lists some publications related to the Preserve.

To access DMWP information, visit the Biodiversity Database website.

Dr. Barrows wrote in the spring 2008 Marsh Wren, the newsletter of the Friends of Dyke Marsh, that there are thousands of “key players” in the wetland’s ecosystem, yet to be studied and recorded.

About invertebrates (including arthropods), BDWA quotes Professor Edward O. Wilson: "The truth is that we need invertebrates but they don’t need us. If human beings were to disappear tomorrow, the world would go on . . . . But if invertebrates were to disappear; I doubt that the human species could last more than a few months. Most of the fishes, amphibians, birds and mammals would crash to extinction about that same time. Next . . . the bulk of the flowering plants . . . and the world would return to the state of a billion years ago. . . ."

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