Migrating to the lower slopes of the Andes in August, cerulean warblers return in April or May to build nests in the upper canopy of forests in the southeastern 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. For its breeding range, the bird needs large areas of mature deciduous forest, often along streams: in the southeastern United States, much of this habitat has been lost to agriculture or development. In its winter range in South America, forests are also being lost to agriculture.
Hamel summarizes what is currently known about the biology of the cerulean warbler and the research questions that remain to be answered. "Cerulean warblers are very difficult to study in the field because they nest and forage in the high canopy," says Hamel. "Fortunately, we have learned a few tricks, such as surveying from canoes and using carved wooden decoys to attract the males. We have also developed genetic tools to help us track the movement of specific populations. We are seeing a dramatic shift in range. Land use change is certainly one cause, but climate change--either short- or long-term--may also be a factor."
Surprisingly little is known about the behavior and population ecology of the cerulean w
Contact: Paul Hamel
Southern Research Station - USDA Forest Service