HI:
Can a UV Field Guide to North American Birds be far behind? I wonder if a
pair of binoculars can be fitted with a lens to see UV light?

--
Ian Paulsen
Bainbridge Island, WA, USA
A.K.A.: "Birdbooker"
"Rallidae all the way!"

---------- Forwarded message ----------
Date: Fri, 19 Nov 2004 13:14:51 -0500
From: Angus Wilson <wilsoa02 at MED.NYU.EDU>
To: BIRDWG01 at LISTSERV.ARIZONA.EDU
Subject: [BIRDWG01] Separation of sibling species

Now if only this applied to Cackling vs Canada Goose :))

Robert Bleiweiss (2004) Ultraviolet plumage reflectance distinguishes
sibling bird species . Proc. Natl. Acad. Sci. USA, 10.1073. Published
online before print November 16, 2004

Abstract: Realistic studies of plumage color need to consider that
many birds can see near-UV light, which normal humans cannot
perceive. Although previous investigations have revealed that
UV-based plumage reflectance is an important component of various
intraspecific social signals, the contribution of UV signals to
interspecific divergence and speciation in birds remains largely
unexplored. I describe an avian example of an interspecific
phenomenon in which related sympatric species that appear similar to
humans (sibling species) differ dramatically in the UV. Both UV video
images and physical reflectance spectra indicate that the dorsal
plumage of the tanager Anisognathus notabilis has a strong UV-limited
reflectance band that readily distinguishes this species from its
sibling congener Anisognathus flavinuchus. The main human-visible
distinction between A. notabilis (olive back) and coexisting A.
flavinuchus (black back) also occurs among different geographic
populations of A. flavinuchus. Notably, however, olive- and
black-backed taxa interbreed (differentiated populations of A.
flavinuchus) unless the additional UV distinction is present (A.
notabilis vs. A. flavinuchus). Thus, UV-based reflectance can be an
essential component of plumage divergence that relates to
reproductive isolation, a key attribute of biological species.