A Case in Point: The Cerulean Warbler
The cerulean warbler, so named for the male's sky-blue plumage, is a neotropical migratory songbird. Migrating to the lower slopes of the Andes in August, cerulean warblers return in April or May to build nests and breed in the upper canopy of forests in the Eastern United States. Since 1966, populations of the species have declined an estimated 70 percent, the decline tied to the fragmentation and destruction of habitat in both breeding and winter ranges.
The northern part of Alabama was once considered the southern limit of the bird's breeding range, but until very recently, there had been very few confirmed sightings since the 1970s. In 2002, the cerulean warbler was designated a species of highest conservation concern in Alabama.
In 2002, Alabama A&M University (AAMU) associate wildlife professor Yong Wang was working with graduate student Adrian Lesak on breeding bird studies on the overstory retention plots SRS researcher Callie Schweitzer had established in Jackson County, AL, (see story on p. 12). Lesak had started his drive home one day when, to his complete surprise, he heard the song of a cerulean warbler.
As a result of his observation, the researchers located the first breeding population of cerulean warblers seen in that area since the 1960s. Since then, another breeding population has been found in the Jackson County area; AAMU student John Carpenter now studies these populations, which in 2004 numbered almost 30 birds. Further south, in the Bankhead National Forest, bird surveys have counted a total of 32 cerulean warblers between 1999 and 2004, mostly in the Sipsey Wilderness Area.
In addition to detailed maps of where cerulean warblers have been found, researchers are able to provide information on the size of their populations, breeding status, and habitat and landscape relationships. Wang and his students have also started to develop Geographic Information System and statistical models of habitat and landscape characteristics that predict areas where the birds are most likely to be found- information that will help resource managers develop strategies to provide or ensure habitat specifically for the cerulean warbler. Paul Hamel, SRS wildlife biologist and national leader of cerulean warbler research profiled in this issue, helped develop this important research.
The work of Wang and his students on cerulean warbler is part of a largescale wildlife study associated with SRS upland hardwood regeneration research in Jackson County, AL. A sister study on the Bankhead National Forest looks at the wildlife community response to thinning and burning treatments. In addition to birds, studies look at snakes, salamanders, bats, frogs, even ants. Many of these studies are the first of their kind for the southern Cumberland Plateau, and invaluable for making clear the connection between silviculture and wildlife habitat. These research activities have been supported jointly by SRS, the National Science Foundation, the U.S. Environmental Protection Agency, and the Alabama Department of Conservation and Natural Resources. -ZH