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Message: <blockquote data-quote="Kirk Roth" data-source="post: 1938237" data-attributes="member: 85015">All the quoted biometrics are statistically significant, which (to a scientist) is what defines a "real" difference.  If your argument is with the overlap in morphology of a minority of individuals in a museum tray, than I guess the issue is with statistics rather than biology - and frankly I'm too tired to argue about that!  I'll end by maintaining 1) that overlapping morphology is a problem with several plant species (Solidago, and other composites, especially), some flies, and probably many others.  And that is without getting into Hugh Patterson's "Recognition Species" concept.  In a taxa with such complex behavior as birds, I'd be amazed if they are exempt from this sort of crypsis.  and 2) I still maintain that breeding behavior, not morphology, is a better basis for species, (or "Type") definition.Very good idea.  To be more challenging, I'd add redpolls to the list.  However, I'd caution that one key aspect of crossbill biology and the assumed driver of population differentiation is a specialized and ephemeral food source.  All of our other finches seem to be moderately general feeders (okay, compared to crossbills anyway).  But they would be very good models for vocalization studies.I don't suppose there are any good data regarding Hispaniolan vs. Two-barred Crossbill vocalizations?  While those have more geographic isolation, I'd wonder if vocalizations vary in a similar way to Red Crossbills.</blockquote>

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