Of the four subspecies of willow flycatcher (Empidonax traillii), three have breeding grounds in California and are listed as endangered by the state's Department of Fish and Wildlife. Because the southwestern subspecies, one of those three subspecies, is listed as endangered by the federal Fish and Wildlife Service, ecologists and conservation biologists have studied the birds closely for decades. Scientists have tried to gather information using traditional research methods such as attaching unique identification bands to the birds' legs, but that provides only limited data because too few of the birds are recaptured for further study.
In the new paper, researchers from UCLA and partner organizations used genetics to produce a clearer picture of where the birds spend their summers and winters, their migration routes, and the threats they face.
Recently, a lawsuit filed on behalf of various industry groups encouraged the Fish and Wildlife Service to remove the flycatcher from the U.S. endangered species list; the agency rejected the request and decided to continue its protections for the bird. Judging by the findings of the UCLA research, that was a wise decision.