Songbird migration study finds a tiny, vulnerable winter range

Prothonotary warblers, songbirds as yellow as sliced mangoes, breed in U.S. wetlands during warm months. Their plumage clashes against dark forests so starkly that a flock of them appears like “butter dripping from the trees,” Ohio State University biologist Christopher M. Tonra said.

Such scenes are increasingly rare. The U.S. Fish and Wildlife Service considers prothonotary warblers to be a species of concern, and in Canada, the warblers are endangered. Tonra and his colleagues recently tracked the declining birds. The goal, as the researchers reported in the journal the Condor: Ornithological Applications, was to discover where the animals spend the winter.