December 2011
  Quick Links
Aquatic: Stream, Pond, Vernal Pool
Wetlands: Low Wetland, Upland Seep
Woodlands: Dry Upland Woods, Moist Upland Woods, Floodplain Woods
Open Lands: Grassland, Edge


Despite its narrow confines and modest length, Sligo Creek Park is home to a wide variety of habitats, each with its own qualities based on soil, sunlight, slope, aspect (facing which direction), and water. Different combinations of these qualities support different sets of plants and animals that are adapted to them.

In Sligo, most of the habitats are distinguished by water. In aquatic settings, the mix of plants and animals depends on whether water is moving or still, deep or shallow, perennial or seasonal. In terrestrial contexts, the flora and fauna are determined by whether the water seeps in gradually through deep soils on slopes, runs quickly off thin, sloping soils; saturates soils on flat surfaces, or emerges from underground seeps. In contrast, Sligo's open areas are characterized less by the behavior of water than by an abundance of sunlight.

The Park's aquatic habitats include streams and tributaries, where wading birds, raccoons, and water snakes hunt minnows and crayfish; artificial stormwater control ponds, where six species of frogs breed every spring; and a few ephemeral vernal pools, where wood frogs and spotted salamanders can reproduce in the absence of fish predators.

Sligo's woodlands consist of dry woods on slopes with thin soils, where chestnut oaks tower above the spectacular blossoms of mountain laurel; moist woods with deep soils, where a host of delicate, spring wildflowers bloom; and flat floodplain woods, where giant sycamores loom and Sligo's largest birds build their nests — herons, night-herons, wood ducks, red-shouldered hawks, and barred owls.

Perhaps little noticed, but particularly valuable, are Sligo's wetlands, with their lush growth of skunk cabbage, in both low wetlands and upland seeps.

Scattered around the Park are tree-less, sunny open lands, comprised of edges and grasslands. The largest of these are at the Pepco powerline corridor, where one finds abundant grasses, summer wildflowers, and a host of butterflies and other pollinators.

CREDITS: Natural Habitats of Sligo Creek Park was developed by Michael Wilpers (FOSC Natural History Committee), based on J. Parrish and R. G. Steinman, Native Plants of the Sligo Creek Watershed (, Friends of Sligo Creek 2003), personal observations, classes in the Natural History Field Studies Program of the Audubon Naturalist Society, and consultation with Laura Mol (Natural History Committee). Format inspired by J. Long, "Habitats of Chapman Forest"(, accessed September 2011, Chapman Forest Foundation, 2008). Habitat categories adapted from Parish and Steinman (above); C. Fleming et al., Finding Wildflowers in the Washington-Baltimore Area (Johns Hopkins, 1995), G. Fleming, The Natural Communities of Virginia: Classification of Ecological Community Groups, version 2.4 (Virginia Department of Conservation and Recreation, 2011,; M. Godfrey, Field Guide to the Piedmont (University of North Carolina Press, 1997); P. Alden and B. Cassie, National Audubon Society Field Guide to the Mid-Atlantic States (Knopf, 1999); and R. Tiner, In Search of Swampland: A Wetland Sourcebook and Field Guide (Rutgers, 2005);

PHOTOS: All photos by Michael Wilpers, except vernal pool, by Ed Murtagh

Habitat Name What It Looks Like What's There Where To Find It
Stream Sligo Creek's waters move through deep, quiet sections (called pools) and shallow, fast-moving sections (called riffles). In pools, about a dozen species of small fish congregate below the surface, while mallards, wood ducks, and water striders occupy the surface. The riffles are where insect larvae, aquatic worms, and fresh-water snails affix themselves to rocks and feed on passing food, especially bits of decaying leaves that fall in great quantities from above.

Throughout the streams, yellow-crowned night-herons hunt for abundant crayfish (their specialty), while green herons, great blue herons, and black-crowned night-herons catch a variety of stream critters, including salamanders. Raccoons do the same under cover of night, leaving many tracks at the water's edge that can be seen in daytime. Water snakes often swim by or bask on rocks and fallen logs, as do snapping turtles. On summer evenings, bats cruise above the creek, catching insects as they hatch into their adult forms and emerge from the water. More often than one might expect, muskrat and beaver take up residence, with the beaver leaving many smalll tree stumps behind.

Left: Sligo Creek main stem, with a deep, quiet pool flowing into a shallow, fast-moving riffle, between New Hampshire Avenue and the Pepco powerline corridor.

Sligo Creek

Wheaton Branch

Long Branch

Smaller tributaries
Pond Sligo's artificial ponds, built for stormwater control, support freshwater snails, small fish, six species of frogs (during breeding season), and a variety of dragonflies and damselflies, among other animals. Feeding on all this life are belted kingfishers, eastern kingbirds, green herons, great blue herons, and black-crowned and yellow-crowned night-herons. Mallards and wood ducks feed on submerged vegetation, sharing the water with Canada geese. Painted turtles and red-eared sliders often bask along the banks or on logs in the summer and spend the winter months buried in the mud at the bottom of the ponds. Occasionally, a beaver will establish a den along the bank, taking down a number of trees in the process and sometimes blocking the pond's exit pipe, causing the pond to flood.

Left: One of the Wheaton Branch stormwater ponds, with geese and goslings afloat.

Kemp Mill stormwater ponds, just north of Univ. Blvd, near the Kemp Mill shopping center

Wheaton Branch stormwater ponds, just south of Dennis Avenue and west of Inwood.

Small ponds just south of the Beltway, between the parkway and the creek

Stormwater ponds just north of Forest Glen Road, between the parkway and the creek

Vernal Pool Wet only during spring and early summer when they accumulate rain water, vernal pools provide important habitats because they contain no fish. With these predators absent, wood frogs and spotted salamanders can breed here in very early spring after arriving from their upland feeding areas, where they spend most of the year. These ephemeral ponds support an array of tiny creatures that provide food for growing tadpoles, including daphnia, seed shrimp, leeches, and isopods.

That's Not a Puddle, It's a Vernal Pool

Vernal Pool Walk - March 4, 2006

Left: Vernal pool in Kemp Mill woodland

Kemp Mill, between hiker-biker trail and the creek, north of the split in the trail

Wheaton Branch, along the foot path south of Woodman Ave. (Breeding frogs & salamanders were last reported here in the 1990s.)

Low Wetland In these low-lying areas, the soil is wet most of the year. Skunk cabbage grows in profusion here and is considered an indicator of valuable wetland habitat. Overhead are water-tolerant trees such as red maple, sycamore, green ash, tulip tree, and pin oak, with abundant spicebush underneath. The wet conditions limit the variety of herbaceous plants, but one can typically find lady fern, New York fern, sensitive fern, Jack-in-the-Pulpit, and bog hemp (false nettle).

Left: Skunk cabbage dominates the herbaceous layer in the wetland across the creek, and a bit upstream, from the Dennis Avenue Recreation Center.

Just north of Dennis Avenue, between the Dennis Ave. Recreation Center and the hiker-biker trail

Kemp Mill, just upstream from the split in the hiker-biker trail, on either side of the trail (this may be a Seep, see below)

Smaller wetlands with Skunk Cabbage located elsewhere in the Park.

Upland Seep When the underground water table encounters the surface along a slope, water emerges to create an upland seep or swamp. Skunk cabbage is abundant, identifying it as a true wetland. Also found there are abundant New York fern, sensitive fern, and Jack-in-the-Pulpit, along with royal fern, cinnamon fern, lady fern, and several sedges.

Left: Cinnamon fern (foreground) and New York fern in the upland seepage area above the west bank of the Kemp Mill stormwater ponds. This is the only location where cinnamon fern grows in Sligo.

See a album of plant photos in an upland seepage swamp in Kemp Mill.

In Kemp Mill, just west of the stormwater ponds

Kemp Mill, just upstream from the split in the hiker-biker trail, on either side of the trail (tentatively identified as a Seep)

Dry Upland Woods Dry woods have steep, rocky slopes and thin soil that cause rain water to run off more than soak in. Chestnut oak is an indicator species for these dry conditions and is abundant between New Hampshire Avenue and the Pepco corridor. It appears with above a shrub layer with mountain laurel and maple-leaved viburnum, and alongside several other oaks, pignut hickory, American beech, red maple, and tulip tree.

Abundant leaf-eating caterpillars in the trees provide food for many birds, while the bountiful acorns are eaten by deer, raccoons, squirrels, chipmunks, mice, woodpeckers, titmice, nuthatches, grackles, and blue jays.

Left: Chestnut oaks and mountain laurel in the dry woods on the north-facing slope between New Hampshire Avenue and the Pepco corridor

Between Piney Branch Road and the Pepco corridor, especially the north-facing slope below New Hampshire Ave.
Moist Upland Woods In moist, upland woods, gentle slopes and deep, rich soil allow rainwater to soak into the ground, providing plenty of moisture for luxuriant plant growth. Most distinctive of this habitat are the briefly flowering "spring ephemerals" such as the widespread mayapple, trout lily, Solomon's plume (false Solomon's seal), and spring beauty, as well as more localized Dutchman's breeches, pink lady's slipper, ramp, star chickweed, and cut-leaved toothwort, all pollinated by native solitary bees. Rich soils in these woods support Christmas and rattlesnake fern, Indian, pipe, and a number of rare spring flowers.

In the canopy are abundant tulip trees, several oaks, mockernut hickory, American beech, black gum, sassafras, dogwood, and ironwood (Carpinus), with a shrub layer of spicebush (especially on lower slopes) and maple-leaved viburnum, with occasional strawberry bush and pinxster azalea. The deep, moist leaf-litter is home to most of Sligo's box turtles. As in dry woods, the abundant leaf-eating caterpillars provide food for many birds, while a reliably vast crop of acorns are eaten by deer, raccoon, squirrels, chipmunks, mice, woodpeckers, titmice, nuthatches, grackles, wood ducks, and blue jays. Red-tailed hawks prefer these woods for their nesting sites.

Left: Mockernut hickory sapling (above) and spicebush (below) in the moist upland woods between the hiker-biker trail and Sligo Middle School

The largest tracts of this habitat are:

Above University Blvd., west/southwest of the stormwater ponds; behind Magruder's grocery story; and north of the hiker-biker trail after the trail splits

Just north of Dennis Ave., between Sligo Middle School and the creek

From the confluence of Sligo Creek and Wheaton Branch northwest to Woodman

Long Branch, between Carroll Ave. and the confluence with Sligo; between the Long Branch Community Center and Melbourne

Floodplain Woods Floodplain woods occur in flat, low-lying areas on either side of the creek and its tributaries. The trees here are species that can tolerate occasional flooding. Specializing on the stream and pond banks are box elder, river birch, the uncommon black willow, and the non-native white mulberry. Here and away from the streams are ironwood (Carpinus), red and silver maple, sycamore, American elm, pin oak, green ash and a few stands of paw-paw, many of which are subject to beaver damage. Spicebush is often plentiful, while silky dogwood is uncommon. As in Sligo's wetlands, the herbaceous layer here is less varied than in other woods, but one can find abundant Jack-in-the-Pulpit, lady fern, New York fern, sensitive fern, false nettle (bog hemp), jewelweed (touch-me-not), sedges, and one tiny colony of turtle-head.

Some of our largest birds nest in floodplain woods, including the often-heard barred owl as well as red-shouldered hawks, wood ducks, and (in trees directly over the creek) black-crowned and yellow-crowned night-herons that migrate to Sligo from as far away as the Caribbean in order to breed here each spring.

Left: Pin oak, with its downward swooping branches, in the floodplain woods downstream from the Kemp Mill stormwater ponds

Watch video of yellow-crowned night-herons nesting and hunting along the Sligo Creek floodplain just above Piney Branch Road in June 2011 (video by Debra Benator).

Kemp Mill, between the stormwater ponds and University Blvd.

Kemp Mill, south of the right-hand fork of the hiker-biker trail

Wheaton Branch, above the confluence with Sligo Creek, up to where it begins to parallel Woodman Avenue

Between the Pepco corridor and East-West Hwy

Stream bank trees, shrubs, and herbaceous plants can be found along the entire length of Sligo and its tributaries

Grassland Grasslands in the Eastern United States were once created and maintained by fire, but today they are provided by annual mowing. Like fire, mowing prevents shrubs and trees from establishing themselves, leaving the field open to grasses and wildflowers. The mowing also helps keep invasive vines and shrubs under control.

The flowers include butterfly weed, common milkweed, boneset, Joe-Pye weed, goldenrods, dogbane, and yarrow, all of which provide nectar and pollen for a variety of butterflies, bees, wasps, and other pollinators who in turn fertilize the flowers. Meadow voles make their passageways in the dense undergrowth, while red-tailed hawks and red fox search them out for food. .

Left: Goldenrod in the grassland along the Pepco powerline corridor

In the Pepco powerline corridor between New Hampshire Ave. and East-West Highway

Across from Sligo Golf Course, between the Beltway & the soccer fields

Just north of the Beltway on the east side of the hiker-biker trail

The hillsides surrounding the Wheaton Branch stormwater ponds (although these are mowed twice a year so that safety inspectors can look for faults that might endanger downstream homes)

Edge Where woodland meets open space, one finds a narrow transition zone called an "edge," which has its own habitat qualities. Sun-loving shrubs are abundant here, providing fruits of great value to wildlife, such as tall blackberry and common and glaucous greenbriers. Also here are plants rarely seen in other Sligo habitats, including winged sumac, trumpet vine, and Hercules' club.

Abundant dogbane and goldenrods provide nectar and pollen for insects. Eastern towhees sing in the trees high above their well-hidden nesting sites, chipmunks dig their burrows underground, and cottontail rabbits escape to the dense thorny cover for protection from foxes.

Also flourishing along these edges are some of our most widespread and aggressive non-native invasives, especially such vines and shrubs as mile-a-minute, porcelainberry, Japanese honeysuckle, multiflora rose, bush honeysuckle, and wineberry.

Left: Plentiful fruits of tall blackberry in edge habitat along the Pepco powerline corridor

Many areas throughout the Park, especially around ball fields, when they aren't covered in exotic invasives such as porcelainberry, multiflora rose, and wineberry

The Pepco powerline corridor, between New Hampshire Ave. and East-West Highway

Wheaton Branch stormwater ponds, along the eastern and southwestern edges of the property

Kemp Mill, the north side of the right branch of the hiker-biker trail