To split or not to split: when eastern and western birds find romance on the Great Plains, the results can create a nightmare for biologists and birders' checklists.

Publication: Birder's World

Publication Date: 01-DEC-97

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COPYRIGHT 1997 Kalmbach Publishing Company

When eastern and western birds find romance on the Great Plains, the results can create a nightmare for biologist and birders' checklist

I don't know about you, but my favorite field guide and my life list are getting pretty marked up these days. Not only species, but genera, families, subfamilies, and tribes seem to regularly come and go. When the idea for this piece was first discussed, Baltimore and Bullock's Orioles had faded into the past. Now, as we sit here today, they've been back for over two years. Back then, the flickers all had been tossed into the same salad. Now, happily, the Gilded has been tossed back out. On the other side, we've gained a towhee without losing one first. Think back further. Remember the Tufted and Black-crested Titmouse? Well, they aren't back yet, but.... Personally, I wouldn't place any final bets on any of these "species" just yet. And I suggest you keep these parts of your life list in pencil.

Certainly, species are coming and going taxonomically in many parts of North America. And a look at the Forty-first Supplement to the American Ornithologists' Union (AOU) Check-list of North American Birds (1983) quickly reveals that we are unsettled in our naming over a much larger geographical area. But no region of the U.S. has presented ornithologists with more reasons to think about what makes a species a species than the Great Plains. At the same time, no region has caused us to fiddle more with our life lists.

The meeting of eastern and western forms in the Great Plains was appreciated at least as early as the late 1800s by Elliot Coues, who described the phenomena in Key to North American Birds. John James Audubon also was involved early on, describing a mixed pair of flickers from Fort Union on the North Dakota-Montana border in 1897. Our elders were tuned into hybrids, and they got us thinking.

According to James D. Rising, who has recently worked extensively on this problem, the orioles, flickers, and titmice are only three "pairs of taxa" out of eleven that hybridize at least occasionally in the Great Plains. The other pairs are the Eastern and Western...

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