Friends of Dyke Marsh is a volunteer group dedicated to preserving, restoring and enhancing Dyke Marsh, a freshwater tidal marsh in Fairfax County on the Potomac River just south of Alexandria, Virginia. The Dyke Marsh Wildlife Preserve is administered by the National Park Service.

What Is Dyke Marsh?

The Dyke Marsh Wildlife Preserve is a freshwater, tidal marsh on the Virginia side of the Potomac River in Fairfax County. It is a unit of the George Washington Memorial Parkway, U.S. National Park Service. For more information, visit the NPS website at www.nps.gov/gwmp.

Dyke Marsh Plants of Late Summer

On August 28, 2021, 18 plant lovers studied the diversity of Dyke Marsh’s plant life, on a Haul Road trail walk led by Alan Ford and Margaret Chatham of the Virginia Native Plant Society’s Potowmack Chapter.

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Two 2021 Bird Sightings Set Records

Buff-breasted Sandpiper

On August 28, Todd Kiraly, Steve Bielamowicz and Sherman Suter saw and reported a buff-breasted sandpiper (Calidris subruficollis) in the Hunting Creek mudflats, just north of Dyke Marsh.  This was a first sighting and a record for the George Washington Memorial Parkway (GWMP).  This is bird number 294 for GWMP. 

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FODMers Shine in Photography Showcase

Green heron

Virginia Wildlife magazine chose the photographs of two talented members of the Friends of Dyke Marsh for the magazine’s annual Photography Showcase, published in the July-August 2021 issue:  Barbara Saffir and Jane Gamble.  Congratulations!

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New, Exciting Sightings

Sunflower maggot fly

On June 9, 2021, FODMer Ed Eder documented a new fly species, Strauzia longipennis, never before confirmed on a George Washington Memorial Parkway property.  Its common name is sunflower maggot fly because its primary host plant is the sunflower.  Adults typically emerge in June.

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Volunteers Continue Insect Surveys

Gray hairstreak butterfly

Since 2016, devoted volunteers have surveyed Dyke Marsh for butterflies, dragonflies and damselflies once a month, often observing many other insects and wildlife too.  Here are a few examples of 2021 sightings. Thank you, Rusty Moran, for your observations and photographs.

The first photo is the gray hairstreak butterfly (Strymon melinus). As its name suggests, this species of butterfly belongs to a group of butterflies with hairlike markings on the underside of their wings. Fairly common, this species lives in a variety of habitats. Its caterpillars feed on a variety of plants.

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The Potomac River's Recovery May Be Stalling

Potomac River

The Potomac River is much cleaner today than it was in 1964 when then U.S. President Lyndon Johnson called it “a national disgrace,” but efforts are still needed to get it to an A grade, Hedrick Belin, President of the Potomac Conservancy, told attendees of a May 26, 2021, Zoom meeting of the Friends of Dyke Marsh. “It is still too polluted for swimming and fishing,” he cautioned.

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Determining the Habitat Quality of an Area Stream

Meredith Kepper

On April 9 and May 27, 2021, FODM volunteers conducted habitat quality monitoring in an unnamed, intermittent stream that flows through Mount Vernon Park  into west Dyke Marsh.  FODM started this project in 2016.

On May 27, the stream had the highest number of macroinvertebrates that FODM volunteers have ever seen there – 206.  “Although most were midges, it was still very, very exciting,” observed Ashley Palmer, Northern Virginia Soil and Water Conservation District (NVSWCD), who led the group. Palmer explains, “Midges are small macroinvertebrates considered to be tolerant of pollution. Finding many midges in a stream usually indicates poor water quality, but at this site we likely find more midges due to the intermittent stream flow which can make it more difficult for more sensitive species to be present.  A healthy stream has a large number and wide variety of macroinvertebrates.”

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Barred Owls Boost Spirits

Barred owl

Spring’s rebirth is always uplifting, especially when Dyke Marsh’s avian heroes and heroines put on a show.  In May 2021, many people delighted in observing a barred owl pair (Strix varia) and their three young near the Haul Road trail.

Josh Brick shared a video of the two adults appearing to display affection or preening.  “It was hard to pull ourselves away,” Josh reported.

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Bald Eagles and Ospreys Put on a Show

Eaglet

In early May 2021, the eaglet pair in one of the nests in Dyke Marsh is growing up.  They are often visible to visitors.  The flapping eaglet is exercising its wing muscles, in preparation for flight.  Young bald eagles typically fledge in Northern Virginia in June.

In these stunning photographs by Ashley Bradford taken on May 2, one of the eaglets leapt up and flapped and got up above the edge of the nest before dropping back down into it.

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Volunteers Are Saving Dyke Marsh’s Trees

Mireya Stirzaker

 In 2021 in five sessions, as of April 4, 2021, FODM volunteers have collected 136 bags of English ivy off trees, an effort to save the trees.

English ivy (Hedera helix L.) is an invasive, evergreen, aggressive invader that can outcompete and smother native plants, block sunlight needed by herbs and seedlings and spread into the forest canopy.

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Flying Squirrels Wow the Crowd

Flying Squirrel

On February 17, 2021, 89 people became instant fans of the native southern flying squirrel (Glaucomys volans) thanks to a much-applauded Zoom presentation by naturalist Kim Young, from Fairfax County Park Authority’s Hidden Oaks Nature Center.

Ms. Young detailed the identifying characteristics, behavior, diet and habitat of these members of the rodent family, animals that weigh about the same as a cellphone, 2 ½ ounces, and are eight inches long, with their tail being from a third to a half of that length.

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