"Answer"
Bill shape eliminates most alcids,
leaving only the murrelets and possibly CASSIN'S AUKLET. CAAU
can be eliminated by the bold black and white head pattern, clearly
visible in this lousy photograph. Absence of white on the scapulars
eliminates MARBLED, LONG-BILLED and KITTLITZ'S MURRELET and the
white throat eliminates ANCIENT MURRELET. We're left with XANTUS'
and CRAVERI'S MURRELET, of which XAMU hypoleucus also
can be eliminated on the basis of facial pattern. XAMU and CRMU
are easily separate by coloration of the wing linings, but we
don't have benefit of that field mark in this photograph. CRMU
has a dark partial collar which extends onto the breast, which
may or may not be present in the photo as it is difficult to
tell the orientation of the body of the bird. However, there
is one remaining unambiguous field mark. On CRMU, the black on
the head extends below the bill, while the on XAMU scrippsi,
the black does not extend below the bill, as is just discernible
in the above photo. This XANTUS' MURRELET, subpecies scrippsi,
was photographed on Monterey Bay in the fall of 1999.
Last updated 24 November, 1999