Walking along the trail on this April day, wildflowers and blossoms dot the ground: bluebells, violets, spring beauties, trout lilies, jack-in-the-pulpit, mayapples, and bloodroot. Redbuds and cherry trees flower along the park’s roadways as bicyclists power up its steep hills.
It may be surprising, but this leafy wilderness is just miles from the White House, in the bustling, traffic-laden city of Washington, D.C.
Rock Creek Park, one of the largest natural urban parks in the country, flows through a stream valley in the city. The main stem of the creek, 33 miles (53 kilometers) long, winds through D.C. for nine miles (14 kilometers) within the park’s boundaries before emptying at its mouth into the Potomac River and ultimately reaching the Chesapeake Bay. (See “How Urban Parks Are Bringing Nature Close to Home.”)
The National Park Service (NPS) administers Rock Creek Park within the city’s boundaries, overseeing the park’s forested 1,754-acre (710-hectare) main section—from D.C.’s northern border with Maryland to the Smithsonian’s National Zoo in the south—as well as an additional 1,300 acres (526 hectares) of smaller, fragmented parks and historic buildings. These different pieces of land make up what’s collectively called Rock Creek Park.
“Rock Creek is a little wilderness area in the middle of the city,” says Ken Ferebee, a biologist with the National Park Service who’s worked in the park for 25 years. “A lot of people don’t realize how big this park is. They just drive through it, they don’t spend time with it.”
Many animals make their homes in the park’s natural landscape. From shad swimming in the creek to ovenbirds rustling through the forest’s understory, it’s a hub for urban wildlife. Yet with more than 30 miles (48 kilometers) of recreational trails, the park’s also a destination—and playground—for city residents, who hike its trails and stroll along its banks.
Congress established the park in 1890, creating an area “perpetually dedicated and set apart as a public park or pleasure ground for the benefit and enjoyment of the people of the United States, to be known by the name Rock Creek Park.”
It outlined a natural vision for the park: “Such regulations shall provide for the preservation from injury or spoliation of all timber, animals, or curiosities within said park, and their retention in their natural condition, as nearly as possible.”
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But that’s created a dilemma for those who manage Rock Creek: How do you preserve the natural habitat of the park and encourage people to experience it at the same time?
It’s especially challenging as the pressure of city life impacts this urban sanctuary on a daily basis.
Among the Wildflowers
Though spring cherry blossoms may be the most well-known flowers of the nation’s capital, the native wildflowers, plants, and trees of Rock Creek Park are striking standouts, too. Bursts of pink, white, and purple color the urban park.
On the park’s Valley Trail, Ferebee points to a delicate flowering plant. It’s called jack-in-the-pulpit because “it looks like someone’s standing inside of it,” he says.
The timing of this fleeting wildflower, as with other spring ephemerals, is critical to the balance of the ecosystem. Wildflowers must complete their life cycle quickly before the canopy leafs out, blocking the sunlight, Ferebee says. Insects consume wildflower seeds and pollinate plants. Returning migratory birds feast on the insects, as do salamanders and frogs. (Explore the “Power of Parks” in National Geographic magazine.)
A native violet tries to peek out amid an overwhelming cover of lesser celandine, an invasive plant commonly called fig buttercup. For the past few years in early March, this section of the park has been treated with an herbicide to reduce the spread of the plant. Celandine outcompetes the park’s native wildflowers, he says, and it’s destroying the ability of native plants to thrive, in turn threatening the park’s diversity.
“People say, ‘Why don’t you dig it up?’” Ferebee says. “I could dig this up for a thousand years and you would not see anywhere near the end of it.”
Ferebee estimates celandine affects some 200 acres (81 hectares) of the park. Other invasive plants, such as garlic mustard and Japanese honeysuckle, are scattered throughout. “The invasive plants are changing the habitat and overwhelming native species,” Ferebee says.
On a sunny afternoon, near the side of the road on Beach Drive, wood ducks and mallard ducks swim in the creek, as three red-eared sliders, a type of turtle, bask in the sun atop a log. Although cars whir by, the ducks seemingly ignore them, dipping their heads down into the water.
A red-bellied woodpecker taps a tree overhead. Many different species of trees grow in the park, including oak, hickory, sycamore, and tulip poplar, which are among the oldest and tallest trees in the park. (See 14 pictures of extraordinary trees.)
Trees remain vital habitat for birds and other species even after they die and fall, creating new homes for critters such as snakes, salamanders, moles, and shrews.
“Mice, insects, and birds use the logs like a restaurant,” Ferebee says. “They peck off the bark to get to where the insects are.”
Fish Out of Water
Situated at the park’s center is Peirce Mill, a restored 19th-century gristmill. In 1904 authorities installed a dam near the mill to create a picturesque setting for visitors. Shortly afterward, the mill was converted temporarily into a teahouse. In the 1930s, NPS restored the mill to its historic design.
As with other changes made in the park, the creation of the dam brought unintended consequences—it blocked the passage of herring, a migratory fish that spawns upstream in Rock Creek.
In 2007, the park service installed a fish ladder to create an upstream path. “The ladder was built for herring to get upstream, but other fish, like shad, use it too,” Ferebee says, as he rakes leaves away from the ladder’s exit so it doesn’t impede the fish. (Also see “Fighting Over Herring—the Little Fish That Feeds Multitudes.”)
In early spring, fish begin moving through the ladder, which helps lift them up by increasing the water’s velocity through a series of about 15 baffles. These devices form pockets of slack water so fish can rest as they’re moving through, allowing them to climb the elevation from the lower creek to get above the dam.
In the afternoon sunlight, a silvery shad suddenly emerges from the ladder’s exit. It waits just outside of the exit, seeming to hesitate.
“It’s using its senses to figure out this part of the creek,” Ferebee says. “Maybe it hasn’t been here before. It’s making sure this is right.” A few minutes later the fish moves on, continuing its journey upstream.
Critters of the Night
Rock Creek Park is a tectonic boundary, straddling the fall line between two geological provinces: the bedrock of the Piedmont and the Atlantic Coastal Plain.
Its high ridgeline along the western side of the park is a hot spot for birds, such as warblers and other neotropical birds, which migrate through the park in April and May.
Near Rapids Bridge, the creek drops in elevation about 70 feet (21 meters). Water-loving sycamores grow close to the creek. Soon wood thrush and ovenbirds will return. The official bird of D.C., the wood thrush, scours leaf litter looking for caterpillars and worms. Their ee-oh-lay song “sounds like someone playing the flute,” Ferebee says, while the ground-nesting ovenbird makes a distinctive “teacher-teacher” vocalization. (Explore National Geographic’s backyard bird identifier.)
Other animals in the park are active at night, like barred owls. The flying squirrel is an elusive nighttime critter, and Ferebee has seen just three of them in the park over the past two decades. A distinctive flap of skin enables flying squirrels “to fly like a kite” when their legs are outstretched, he says.
Along the Valley Trail, a woodpecker drums against a tree, perhaps to attract a female. Ferebee stops at a fenced area, erected to keep dogs away, surrounding a pool of water.
The seasonal spring pool is critical habitat for the park’s amphibians, such as wood frogs and spotted salamanders, both of which lay their egg masses here. But when Ferebee made his most recent egg count in the middle of March, their future wasn’t looking good. (See “In New Drainage Projects, Long-Buried Urban Streams See the Light Again.”)
This year’s dry spring, and the warmer spring days in March and April, Ferebee says, have put the park’s amphibians in danger since the pool is drying up too early in the season. A lack of precipitation, evaporation from the sun, and trees drawing water out of the ground as they grow and leaf out all affect the pond, he says.
“All this stuff is timed. Since 2003, we’ve only had two years when there’s been water in this pond at the end of June,” he says. If the pond dries up before the larvae mature in May or June, they can die, he says.
“We’re losing habitat,” Ferebee says.
On a Tight Leash
Many people enjoy walking their dogs in the park. Though legally dogs should be leashed, Ferebee says many people overlook that. “When a dog runs through,” he says, “everything stops. This is not a dog park, but people treat it like one.”
Unofficial trails, called social trails by park officials, create shortcuts from nearby neighborhoods into the park. People often walk their dogs down these trails, creating more fragmentation and disturbance, which causes erosion and sedimentation in the creek.
“We have a huge problem with social trails,” Ferebee says, estimating that there are perhaps two times as many social trails as official ones.
Trampling dogs place more pressure on already fragile animal populations. As they race through the underbrush, dogs create bare areas and may disturb ground-nesting birds and squirrels. If a dog chases a bird off its nest, Ferebee says, a snake may come in and eat its eggs.
Dogs can harm spring ponds with amphibian eggs, too. If they stir up the pool, sediment covers the eggs and blocks the sunlight and warmth the eggs need to develop.
“The native animals are already under stress living in the city,” Ferebee says. “A lot of animals are already living on the edge. Just surviving is a daily challenge for some of them.”
Though the park service has treated invasive plants and restored much of its ground cover, the challenges of city life remain.
Road traffic and the park’s proximity to neighborhoods exert daily pressure on Rock Creek’s animals and plants.
The interactions between plants, animals, and people in the park matter, Ferebee says. “It’s all a balance.”
Christy Ullrich Barcus is the author of the National Geographic book The Angry Birds Movie: Red’s Big Adventure.