>I couldn't help notice that (by some aberration) tweeters is discussing birds (
>or ornithology, or something out of character anyway), so I thought I'd pose a
>question. Some months ago an extremely alert Oregon Birder discovered an appar
>ent hybrid Chestnut-backed x Black-capped Chickadee in Albany OR. Are tweeters
> aware of this? Us locals don't know of any other reports of this hybrid betwe
>en two species with broad range overlap in the NW (I said it, didn't I). Has a
>nyone heard of this hybrid being recorded previously? If not, why not? What r
>elevance does this one bird have to the species concept? None at all? (Anyway
>, I'm doing my best to prolong this conversation, thereby forestalling (for now
>) a return to limericks.
>
>PS This is NOT an invitation for a limerick on hybrid chickadees or the specie
>s concept, or any other subject either.
>
>Bob O'Brien

I have never heard of this hybrid combination before, but I have seen both
a specimen and a wild bird that I thought were hybrid Black-capped X
Mountain chickadees. Isolated hybrids of this sort have absolutely no
relevance to the species concept, but it is always of interest to see what
species will hybridize, especially in nature; it probably gives us some
indication of relatedness (don't read this, David). For example,
goldeneyes and mergansers have hybridized frequently, which seems bizarrre,
yet in fact they're not distantly related, something that wasn't realized
when the first hybrids were reported. And juncos hybridize with some
sparrows, again a little surprising until you realize that they are in fact
closely related.

Many hybrids have been produced in captivity, even between birds that don't
seem especially closely related. This is probably because if you put a
male of species X and a female of species Y in a cage, lacking appropriate
mates but possessing an urge to breed, they may eventually get it on.

About hybrids--the burden of proof is on the hybrid proponent, as sometimes
an easier explanation is that a bird is an aberrant individual of its
species. If I recall correctly, the Black-capped X Chestnut-backed was
never photographed or captured and measured, which is a shame.

Don't be so sensitive to limericks, Bob! You may not like that particular
brand of humor, but humor is the greatest antidote we have to reality.

Dennis Paulson, Director phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416