Tuesday, July 11, 2006

Chickadees, Titmice and DNA

The current issue of Birding magazine has some interesting notes about recent research on chickadees, titmice, and other members of the Paridae family. (The report in Birding summarizes a study published last year in The Auk.) Researchers determined that the genus Parus, which used to contain all chickadees, titmice, and related species, should in fact be broken into multiple genera. The suggested division includes Poecile (chickadees) and Baeolophus (titmice) in North America. Eurasian and African tits are now divided into Parus, Lophanes, Periparus, and Cyanistes. The split of New World chickadees and titmice into the Poecile and Baeolophus genera is not new; the AOU recognized the split in 1998.

For North American birders, the results regarding chickadees are intriguing. Though the black-capped chickadee and carolina chickadee interbreed and are similar enough in appearance to make identification difficult, they are not as closely related as one might think. Instead, black-capped is more closely related to the mountain chickadee. Among carolina chickadees, there are significant genetic differences between the two subspecies, the eastern extimus and the carolinensis subspecies in Louisiana. Whether that would be enough to call for a species split is not addressed in the Birding summary.