[Tweeters] Re: Crossbills

Mike Patterson celata at pacifier.com
Wed Jun 8 10:14:04 PDT 2005


There are 9 to 9 North American subspecies of Red Crossbill
(depending on how you do the math) plus White-winged Crossbill
which means up to 10 "kinds" of crossbills in North America
(Eurasian has at least 3 more). Sibley's lays them all out.

Jeffrey Groth advocates splitting them all (see:
http://research.amnh.org/ornithology/crossbills/diagnosis.html )

The most diagnostic way to sort them is by vocalizations. Overall
size, bill size and color work to a lesser degree and require
considerable practice with all forms. The way the bill crosses
is not considered a taxonomically significant character.

I doubt that the AOU will split all forms. The very large "Mexican"
Crossbill (type 6) is the most likely split and the very small "Sitka"
Crossbill (type 3) is a fair bet. The stuff in the middle is squishier,
and if one of these gets split all would pretty much have to be
split...

--
Mike Patterson
Astoria, OR
celata at pacifier.com

Go, and sin no more (ethics in birding)
http://www.surfbirds.com/blogs/mbalame/archives/002555.html



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