In response to several postings, it sounds as if there is concern about
there being species out there that we can't recognize. Does that mean that
bird listers should be the arbiters of species limits and bird taxonomy? Or
maybe avian ecologists, because they wish to study community ecology and
need to know the exact identity of each species?
It sounds to me that this would be the tail wagging the dog. I
think that science is a search for the truth, and if the truth is that
there are 8 species of "red crossbills" out there, then that's that (I
realize there will be good healthy debate on scientific bases in any case).
Let the ABA and birders have Red Crossbill for their lists, and let people
who are interested in evolutionary biology and biodiversity try to
understand how 8 "red crossbills" evolved and can coexist now. In fact,
each type of crossbill does know itself--they respond preferentially to
tapes of their own calls! And we have abundant evidence from other
taxonomic groups that very distinct species may look alike to us. Why
should that be displeasing or frustrating?
My own opinion is that it's wonderful that we can't pigeonhole
everything just exactly as we would like it. If two species are different,
why should we retain the fiction that they aren't just because we can't
identify them in the field? Some small mammals can be identified only by
looking at their skulls, so what are the mammal listers in the American
Mammaling Association to do? It gets worse when you get into salamanders
and other creatures that tell each other apart probably entirely by smell.
Are we to say they don't exist just because we don't know what they are
when we pick one up?
I have now seen several comments from birders who condemn the
existence of species they can't identify and, I guess, those researchers
who unearth such species. I'd be interested in learning more about this
attitude, which is so different from my own.

This Timberline Sparrow discussion shows the incredible value of
e-mail!!!!! Would that everyone had access to it (although, come to think
of it, maybe not.....).