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Desert Diary


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Superficial knowledge sometimes confuses more than it enlightens. Biology students learn that, by the most commonly used definition of species, populations of organisms that are able to freely breed with each other are considered to be members of the same species. They also learn that individuals belonging to different subspecies have to live in different places, since they're members of the same species. This, of course, is because if they lived in the same geographic range, any differences between the subspecies would quickly break down due to interbreeding. And thus, no longer different subspecies.

So what's a fellow to think, if he hasn't worked it through, when he sees two or three subspecies of snowbirds, which you may know as juncos, cavorting in the snow in the El Paso winter? Isn't this proof that they're really separate species. Come on, now, do you see any nests or eggs? Many birds migrate, remember? Come warmer weather, when snowbirds begin to think of building nests instead of snowballs, these separate subspecies will disperse to their breeding grounds--their SEPARATE breeding grounds!
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Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.


Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.