As birds go, the cerulean warbler is very hard to spot. At just four inches, it is small even for warblers, and it forages and nests high in the canopy. With its numbers plunging by nearly 80 percent during the past four decades, it’s becoming even more elusive. “There are very few species anywhere that are declining as steadily and as steeply as the cerulean warbler is,” says Greg Butcher, Audubon’s director of bird conservation.
The U.S. Fish and Wildlife Service (FWS), however, decided this past December not to list the bird as a threatened species under the Endangered Species Act, having determined that it’s holding its own. “The cerulean warbler was not a species you had to bring into the emergency room,” says Charlie Scott, field supervisor with the FWS’s Missouri Ecological Services Field Office, who participated in the review process. The decision comes six years after several conservation organizations, including Audubon and Defenders of Wildlife, petitioned the agency to consider listing the bird.
About 400,000 ceruleans remain, based on estimates from the Breeding Bird Survey, which monitors the status and trends of North American bird populations. If the cerulean population continues to decline at the current rate of about 3 percent per year, some scientists estimate that within a century their numbers could drop by 90 percent. The FWS maintains that the projection is too far in the future to warrant a listing now—even though the threats the bird faces, which include development, forest management practices, and mountaintop removal mining, will probably push it even more quickly toward extinction. “If there is any doubt, the nod should go toward protecting the species,” says Andrew Hawley, an attorney with Defenders of Wildlife.
While the cerulean’s summer range extends across 33 U.S. states, its breeding area is centered in West Virginia, parts of Ohio and Kentucky, and the Cumberland Mountains of Tennessee. It prefers mature deciduous forests with vertical canopies and small gaps, at times along mountain ridges—the same areas targeted by mining and timber companies.
Filling the void left by the FWS decision, the Cerulean Technical Working Group—made up of agencies, scientists, Audubon and other conservation groups, universities, NGOs, and timber industry representatives—meets periodically to discuss the latest research and to plot strategies to protect the bird. For example, a four-state silviculture study under way in the core of the cerulean’s domain aims to test a range of forest management practices—such as selective logging—to see how the ceruleans respond.
Meanwhile, at least six conservation groups are already reviewing the decision to see if another petition is necessary, maintaining that listing the bird would give more clout to their current efforts by restricting further habitat destruction. “We just know that no species can sustain these losses in the future and remain viable,” says Butcher.—Julie Leibach