While researching which birds were being seen where on TEXBIRDS (a listserv to report bird sightings in Texas) i happened upon a post that linked to an article on Planet Ark, Genetics Reveal 15 New N.American Bird Species. It appears that DNA studies are showing that there are some birds that were thought to be all the same but are, in fact, different enough genetically to possibly be considered as separate species:

OSLO - Genetic tests of North American birds show what may be 15 new species including ravens and owls -- look alikes that do not interbreed and have wrongly had the same name for centuries, scientists said on Sunday.

If the findings from a study of birds' DNA genetic "barcodes" in the United States and Canada hold true around the world, there might be more than 1,000 new species of birds on top of 10,000 identified so far, they said.

In addition there were others that have long been thought to be separate species but are so close genetically that they might be considered to be the same:

"Some of these on close inspection may really be better considered as a single species," said Stoeckle. "Others are probably very young species at the borderline."

The Snow Goose and Ross's Goose, for instance, shared 99.8 percent of DNA and the black-billed magpie and the yellow-billed magpie 99.6 percent. Gulls such as the Glaucous and Iceland Gulls were 99.8 percent the same.

One area that the article does not touch on is if the birds that were sampled were geographically isolated from one another. Things might get a bit tricky if you needed to get a feather tested to determine which exact species would be a "tick" on your life list . . .

(Planet Ark is an Australian website with information and news about the environment.)