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

Do Trees Have Antifreeze?

Jessie Strother

FODM Board member Jessica Strother, a forester, led a walk on February 27, 2016, and described three of the ecotones of the preserve:  the swamp forest, the floodplain forest and the tidal marsh.  She explained that trees breathe through their leaves and root system.  Trees like the pumpkin ash tolerate water, but cedars like drier, upland soil. 

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How Noise Affects Birds

Dr. David Luther

On February 28, 2016, Dr. David Luther, George Mason University biology professor, gave a presentation to FODMers and friends on his research analyzing the effects of noise on birds’ communication, a field called “acoustic ecology.”  Generally, birds sing to attract mates, to defend territories and to establish “social status,” he told the 75 attendees.  In urban areas, anthropogenic noise, like the noise from traffic or gardening tools, can cause birds to change their behavior and their songs.

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The January 2016 Oil Spill

Canada geese

On February 22 at Belle Haven Park, several members of the Friends of Dyke Marsh attended and helped release 21 Canada geese that had been oiled and cleaned by staff of Tri-State Bird Rescue and Research of Newark, Delaware. 

FODMers and others reported to local, state and federal authorities on February 3 that an oil sheen was in the water at the Belle Haven Marina.  Two people photographed an oil sheen that day, one at the marina and one at 7831 Southdown Road, almost a mile south of Dyke Marsh.  Tri-State staffers said they were called on February 4 and that they and others caught birds for a week at Roaches Run, Hains Point and Gravelly Point. 

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Spring Courtship Has Begun

Barred Owl

Spring is underway in Dyke Marsh, especially in the “bird world.”  Former FODM President Ed Eder has taken these beautiful photographs and made a video of some recent bird sightings in Dyke Marsh.

Two barred owls (Strix varia) have been seen near the Haul Road.  Here is one flying through a sweet gum tree.

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Christmas Bird Count Included Dyke Marsh

Red shouldered hawk

Many FODMers participated in the National Audubon Society’s annual Christmas Bird Count (CBC) in January 2016.  Larry Meade, president of the Northern Virginia Bird Club, gave this report in the club’s February newsletter, The Siskin:

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NVCT Volunteers Tackle Ivy and Trash


On the morning of January 18, 2016, the annual Martin Luther King Day of Service and winter’s coldest day so far, 20 hardy volunteers organized by the Northern Virginia Conservation Trust (NVCT) visited the Dyke Marsh Wildlife Preserve.   Braving temperatures in the high teens and a brisk wind whipping across the river, the group removed English ivy climbing up trees and collected five bags and a plastic crate of trash. 

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Hoping to Repopulate Pumpkin Ash Trees

Pumpkin ash seed

In September 2015, a team from the North Carolina Botanical Garden, working with National Park Service staff and the Friends of Dyke Marsh, collected thousands of pumpkin ash seeds (by the bunch, pictured) from a score of different trees in the preserve.  The team has concluded that the seeds are likely viable and in early 2016, they are drying them for long-term storage. 

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Nature's Exquisite Timing


Among many other accomplishments, Henry David Thoreau and Thomas Jefferson were diligent phenologists.  They kept detailed journals in which they recorded the timing of events in nature -- when trees leafed out, when flowers bloomed, when the ground was warm enough to plant.

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The Sounds of Dyke Marsh

American bullfrog

FODMer Laura Sebastianelli lives on the edge of the western part of the Dyke Marsh Wildlife Preserve, the 26 acres west of the George Washington Memorial Parkway, a place she describes as "rich with natural sounds."

Laura admits to a “natural bias,” meaning she loves the sound of nature.  She wrote, "Now technically nature includes us humans, but I confess my bias is for birds, insects, frogs, toads, mammals, gentle wind blowing through treetop leaves and water lapping at shoreline edges." 

With this playlist, Laura shares some of the wonderful sounds of Dyke Marsh. American bullfrog picture courtesy of Laura Sebastianelli.

FODMers Clean Up Trash


Despite a steady drizzle on November 7, 2015, fourteen FODMers and friends donned their rain gear and cleaned up trash in Dyke Marsh West for almost two hours at low tide.  The group collected eight bags of plastic and glass bottles, metal cans, tennis balls, plastic bags, styrofoam, cardboard and more. 

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