High on many out-of-towners' list of birds wanted on their Monterey Bay
boat trip is Craveri's Murrelet (and as Van Remsen used to remark, this
Italian name rhymes with "spaghetti", so say it correctly). If one is lucky
in August-October, and waters on the Bay are calm, one might come upon
a Xantus's/Craveri's Murrelet on the water. Alas, these tiny birds (often
found in pairs) tend to dive actively, are up only briefly, and then fly
straight away, giving poor views of the underwings. Some observers will
just see whatever species they "need" for their lists, regardless of identification
points, a situation I've seen many times. Although we can't see the underwings
on this bird (bright white in Xantus's, dark in Craveri's), we can see
(a) a fairly short and comparatively stout bill for this group, (b) the
lack of any shoulder extension down toward the breast, and (c) what looks
like a white chin (hard to see but diagnostic). This bird is a Xantus's
Murrelet of the northern race scrippsi, which is typically the
more likely species on Monterey Bay. Having plenty of experience with both
species, I now find bill size/shape to be very useful in the field (with
initial impressions often confirmed later by underwings or other features).
A real Craveri's Murrelet (in flight) is shown at right. We can see the dark underwings on this bird -- making identification easy -- but note the (a) longer and therefore thinner-appearing bill, (b) a bit more hint of a shoulder extension (some are more prominent), and notice (c) how the black of the face curves down at the base of the bill and includes the chin. Notice also the broader blackish sides & flanks. And finally notice the whitish patch in the underwings. It is common for Craveri's Murrelet to show patchy dark-and-white underwing coverts, while those of scrippsi Xantus's are always gleaming white. Only a minority of Craveri's Murrelets have completely dark underwings.