"Coevolutionary Arms Race Causes Ecological Speciation in Crossbills," Julie
W. Smith and Craig W. Benkman, AMERICAN NATURALIST 2007 169:455-465.

The new critter has been described at a morphologically and vocally distinct
type of  Red Crossbill restricted to the Soth Hills and Albion Mountains of
southern Idaho.  They are reproductively isolated with more than 99%
breeding with their own kind, per the authors.

Full details at www.eurekalert.com , click on Biology, and troll down.

Whether you buy this or not, the day field nightmare of a 9+ species split
of the Red Crossbill is not far off!

Kurt Schwarz
HowCo
goawaybird at comcast dot net