A gap of about 340 miles divides the two breeding populations of Painted Bunting: one in the southern Great Plains and the other along the southeastern Atlantic coast.
Ornithologists have speculated for years that the two groups represent distinct species, largely because they winter and breed separately and molt and migrate on notably different schedules.
A genetic study published in 2011 may help decide if the species should finally be split. It showed the two populations are evolving independently “with no measurable gene flow between them” and that they began breaking away from each other between 26,000 and 115,000 years ago. Author Connie A. Herr wrote that they “should be recognized as separate management units” for conservation purposes, but she didn’t suggest the species should be split officially.
In July 2014, Robert C. Tweit, a past president of the Western Bird Banding Association, a former editor of North American Bird Bander, and the author of dozens of accounts in the Texas Breeding Bird Atlas and the Birds of North America series, proposed that the classification committee of the American Ornithologists’ Union declare the populations unique species.
The buntings’ distinct ranges, behavioral differences, and lack of gene flow show that they are reproductively isolated, he says. The committee is expected to announce its decision this summer.
A version of this article appeared in the April 2015 issue of BirdWatching. Subscribe.
Read the proposal
Tweit, Robert C. Split Passerina pallidior from Painted Bunting P. ciris. July 7, 2014. AOU Classification Committee – North and Middle America, Proposal 2015-A-7 (PDF).