There’s something truly mysterious about the wood thrush. It’s small, tinier than its robin cousin. Its cinnamon brown color provides camouflage in the branches and shrubs that the bird calls home. And the wood thrush’s call, made to defend territory and attract mates, sounds as if it emanates from a big, complex instrument rather than this delicate creature. Although the bird’s range is large, reaching from Canada to Minnesota to Mexico, it is particularly beloved in the D.C. region. Besides Rock Creek, it can be found in Glover-Archbold Park, Fort Dupont Park, along the C&O Canal and in the many large wooded areas that dot the suburbs. In fact, in 1967, the wood thrush was declared the District’s official bird by the board of commissioners. This despite The Washington Post’s initial protests that the wood thrush spent only five months of the year in the region.
But, like many of North America’s migrating birds, the wood thrush is in trouble. According to a 2016 study led by Smithsonian researchers, the number of breeding wood thrushes in the United States has dropped by more than 60 percent in the past five decades. “They are the poster child of declining forest songbirds,” says Calandra Stanley, a postdoctoral fellow at the Smithsonian Migratory Bird Center who’s studying how to protect the wood thrush. “There’s a mixture of factors. But the big one is habitat loss.”
Wood thrushes make their home here in the spring and summer, then migrate south to the warmer climates of Central America in the winter. They return to the D.C. region to breed in mid-April to early May, a million songs announcing their presence. Wood thrushes can produce two clutches of eggs a year with three to four eggs per clutch. That means potentially six to eight chicks annually. However, it’s a tough life for a migrating bird. Rauch explains: “A small bird, traveling thousands of miles — just think of all the things they could run into: predators, cars, glass, power lines, hunters, storm systems.” Rauch estimates that even under ideal conditions, about half live through their first year. But if that were the case, wood thrush numbers would be rising.
Instead, they are declining as suitable habitat disappears. Wood thrushes need vibrant, large wooded areas to survive. They nest in shrubs and eat caterpillars and larvae that live in the undergrowth, and the tree canopy helps limit hungry hawks’ field of vision. The D.C. region has had a massive reduction in forests in recent years due to urban development. As forests become fragmented, the birds are forced into smaller and smaller areas. It’s like being forced to move from a six-bedroom mansion to a studio apartment. “There may be a lot of trees in the D.C. area, but there isn’t a lot of complete forest cover,” Stanley says.
This has left the wood thrush even more vulnerable to other factors, such as climate change and, specifically in Rock Creek Park, an ever-increasing deer population. According to the National Park Service, a healthy deer density is 15 to 20 per square mile. In recent years, that density has reached 100 per square mile, prompting the need for an annual park culling. “Deer are grazers and eat everything on the ground: acorns, sapling trees and lots of native plants,” affecting birds that nest closer to the forest floor like the wood thrush, says Scott Sillett, head of the Smithsonian Migratory Bird Center. “[Deer] can shut down the forest’s natural cycle of regeneration, which can compositionally change the forest and lead to the loss of certain species.”
Although the wood thrush isn’t yet considered a threatened species in the United States (it is, though, in Canada), declining numbers, increasing development and climate change factors have led to some dire predictions. The NPS, using a 2013 agency-sponsored report, assessed that there is a 75 percent chance that wood thrushes will totally be gone from parts of the D.C. region by 2100. This statistic isn’t shocking to scientists and experts. Sillett compares the wood thrush’s plight to that of the Kentucky warbler, a small, bright yellow bird that he says has gone extinct from the Washington region in the past several decades. Stanley agrees that it’s a major concern. “There’s been 3 billion birds [total] lost since the 1970s. It’s happening right in front of us,” she says. “In D.C., where there’s so much development, it’s completely a reality that in D.C. proper, we may no longer have wood thrush.”
Yet history provides some hope. In 1970, bald eagles were in rapid decline in the United States and nearing extinction. But a nationwide effort to protect America’s beloved winged symbol, including the banning of the pesticide DDT, new legislation, stricter law enforcement, better power line design and general awareness of its plight, shot its numbers back up within a decade.
Stanley sees that potential with the wood thrush. She says it’s about land management, making conscious decisions to preserve larger swaths of wooded area. The wood thrush is also comfortable in “second-growth habitats,” previously cleared areas that have been regrown with native planets, trees and underbrush. Says Stanley: “It’s something we don’t talk about enough ... how to conserve landscape. Maybe that means building up instead of out and protecting forests that are large enough to be useful.”
Even providing small wood-thrush-friendly habitats in your backyard, where they can stop during migration, helps, Stanley says. They should be full of native plants, berry-producing shrubs (so they can fatten up for their long journey) and a water source. “If we try to address these issues, I think we have a chance of returning the population,” she says, “or stopping the decline, at least.”
Matt Blitz is a writer in Washington.