Reaching only about 4 inches tall, with a wingspan of 7 to 8 inches, cerulean warblers can be hard to find in the deep woods where they live. But when you see them, you can recognize them by their beautiful blue coloration. "Cerulean" means "sky blue." Males tend to be more of a true sky blue, while females are generally more turquoise.
Cerulean warblers depend on mature deciduous forests for their habitat. They like to remain high in the tree canopies, foraging for insects. They are a songbird and are members of the wood warbler family; however, only males sing, producing a distinctive rapid buzzing sound.
In addition to being a songbird, the cerulean warbler is also a migratory species. During the summer, cerulean warblers are found in southeastern North America where they breed, and in the winter these birds travel to northern regions of South America.
Females make a small, open-cup nest using bark, grass stems, and twigs, which are all bound together by spider webs. Both male and female birds take care of the nest and the baby birds until they are ready to fly out of the nest.
Population in Decline
The cerulean warbler has faced a steady decline in population since the 1960s—almost 75 percent of the original population has disappeared. These birds are at high risk of extinction for several reasons, primarily the loss of large contiguous areas of forest habitat.
This is particularly an issue with nesting. Without the dense forests, brown-headed cowbirds can find cerulean warbler nests more easily, leading to nest parasitism, which is what happens when brown-headed cowbirds lay their eggs in warblers’ nests, often pushing out the warbler eggs. A mother cerulean warbler can’t distinguish the cowbird eggs from her warbler eggs, so she continues to care for the invading chicks, often at the expense of her own.