|California Scrub-Jay, Bodega Bay, California|
Photo: Shari Zirlin
Since "species" is a slippery definition, it isn't often clear if birds that look very much alike are sub-species of one another or actually different species altogether, or, the opposite, if birds that look different are actually the same species. A the dictionary definition of species, an animal that mates with another of the same species to produce offspring that in turn are able to reproduce, isn't really applicable in many cases. Many birds hybridize and their progeny are capable of reproduction--otherwise there wouldn't be any backcrosses to drive birders nuts. Every dabbling duck you see probably has some Mallard in it. With DNA now playing the major role in determining what is and isn't a species, and with lots of Ph. D candidates looking for a thesis, every year produces "new" species and every year birds get lost. The cool thing is to get an "armchair bird" on your list, one where a bird you have already seen suddenly becomes a different species, which is why it pays to pay attention to sub-species.
I haven't traveled enough to have this happen to me very often. The only example I can think of up 'til this year is whip-poor-will. When we first heard the Eastern Whip-poor-will in our backyard I was excited because I thought it was a new state bird. We'd heard whip-poor-will in Arizona, years before. But when I went to enter the bird in eBird I saw that sometime since our trip to Arizona, whip-poor-wills in the west had become Mexican Whip-poor-wills, so not only was the whip whooping away dementedly in our backyard a state bird, it was also a lifer.
So I was pleased to read, this summer, that the Western Scrub-Jays we had seen in California and the Western Scrub-Jays we had seen in New Mexico, were, based on arcane DNA analysis, actually two species, the former California Scrub-Jay and the latter Woodhouse's Scrub-Jay. Nice, I thought, number 778 on the list.
|American Coot, Clove Lakes Park, Staten Island|
And for all I (or according to one theory I've read, ornithologists) know, the Eurasian Coots we saw in France are also the same species but since they don't migrate and the populations are isolated from one another we'll never know if they could mate with it each other in the wild. Isolation supposedly leads to speciation--but not necessarily.
So my life list stays at 777--I'm lucky it's that number because there was a lot of speculation that Hoary Redpoll was just a sub-species of Common Redpoll (their DNA supposedly matches in the high 90's) and would be lumped. Considering that I went to Minnesota and froze my ass off to get that bird it would be a big disappointment to find out that it was "just" a Common Redpoll in the end.