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Ecology Walk in Dyke Marsh

Charles Smith Charles said that the horse chestnut tree (Aesculus hippocastanum) at the beginning of the Haul Road is an early succession species and grows well in disturbed systems.

It was all about geology, plants, forests, wetlands, uplands, birds, mammals, reptiles, insects, how everything interrelates and more on the June 10, 2017, ecology walk with Charles Smith, expert naturalist and Chief of Fairfax County’s Stormwater Planning Division, Watershed Projects Implementation Branch.

Smith described the geology of Virginia’s coastal plain and told the 35 enthusiasts that the Dyke Marsh Wildlife Preserve’s Haul Road trail, around seven feet above sea level, could be under water by the end of the century because of sea level rise.

The Haul Road, basically fill, was built by Smoot Sand and Gravel, the company that dredged away almost half of Dyke Marsh between 1940 and 1972.  Both sides of the Haul Road represent “decades of disturbance and re-disturbance. It’s a very compromised landscape,” Smith told the group.  Nevertheless, throughout the preserve, there are different habitat types, a rich biodiversity and many valuable natural resources.

Among many other sightings, walkers spotted an orchard oriole (Icterus spurius) and an Eastern garter snake (Thamnophis sirtalis sirtalis), as red-winged blackbirds (Agelaius phoeniceus) called vociferously and ospreys (Pandion haliaetus) soared and hovered.  Known bird nests near the Haul Road this spring are those of the Eastern kingbird (Tyrannus tyrannus ), yellow warbler (Setophaga petechia), warbling vireo (Vireo gilvus), orchard oriole and two cedar waxwings (Bombycilla cedrorum).  Ed Eder reported that there are eight or nine nests within several hundred yards beyond the “dogleg.” The group was encouraged by a marsh wren (Cistothorus palustris) calling.  For the first time in over 20 years, FODMers did not document marsh wrens nesting in Dyke Marsh in 2015 or 2016.

Photographs contributed by Glenda Booth

Box elderThe box elder or ash leaved maple (Acer negundo), a native tree, is sometimes called the “poison ivy tree” because its “leaves of three” resemble the poison ivy plant (Toxicodendron radicans).

Short-tailed shrewThis short-tailed shrew (most likely Blarina brevicauda) probably died a natural death. It is an aggressive, feisty rodent and probably “burned out,” Charles explained.

Porcelain berryUnfortunately, the Haul Road is overrun with invasive plants like porcelain berry (Ampelopsis brevipedunculata), which strangles many valuable native plants.

River bulrushThe river bulrush (Bolboschoenus fluviatilis), is designated as a rare plant in Virginia. It is usually found in the upper tide range.

Silky dogwoodThe silky dogwood (Cornus amomum) was in bloom.

Three-square rushAlong the water’s edge is three-square rush (Scirpus americanus), a shoreline stabilizer and cover for waterfowl and spawning fish.

Native grapesNative grapes (Genus Vitis) were also in bloom.

Pandorus sphinx mothUnder the leaf of a bear’s foot or hairy leafcup plant (Smallanthus uvedalius), FODMers saw a Pandorus sphinx moth (Eumorpha pandorus). It has a wingspan of 3 ¼ to 4 ½ inches. Females lay eggs on the host plant, primarily grapes and Virginia creeper (Parthenocissus quinquefolia).

Sensitive fernThe sensitive fern (Onoclea sensibilis) is thriving next to the boardwalk (except for the invasive porcelainberry vine that might smother it).

Swamp roseSwamp roses (Rosa palustris) were in bloom.

Five-lined skinkFive-lined skinks (Plestiodon inexpectatus) are usually close to the ground, Charles said. The male is copper colored with an orange head. This skink lost its tail to a hungry predator and can grow the tail back.