I have noticed a recurring theme on Tweeters. Someone will report a call or
song they have heard which belongs to a bird that "shouldn't be here right
now" or "doesn't occur here ever". The usual reply is "Probably a starling"
which is invariable followed by another reply: "I've heard starlings mimic
(insert your favorite example) but I've never heard them do *that*! :(

I would like to remind my fellow Tweeters of two things: 1) starlings are
great mimics (just because you haven't heard them do it doesn't mean they
can't) and 2) mimics continually learn new sounds to mimic, even starlings.

Starlings belong to a large, cosmopolitan family, Sturnidae, that includes
many mimics. (Aren't mynas in that family?) The closest genetic relative to
the sturnidae are the mimids (catbirds, thrashers and mockingbirds); some
people suggest they should be in the same family. Granted, starlings aren't
the best mimics; mockingbirds are much better. Starlings usually sound like
a starling imitating something but they can fool even the best
birder/ornithologists. The traditional response is "I've never heard a
starling do *that*!" :) I could bore you for hours with countless examples
from my own experience but I won't. It is particularly embarrassing when
you have to tell your ornithology students that the awesome raptor you where
looking for is actually that ugly, black bird right above your head. (It
usually happens on the first field trip when they don't how good their TA
really is. They immediately decide that they will go with the professor on
the next field trip.)

Many mimics continue to learn new sounds all of the time. The brain of a
bird continues to grow throughout its life. In mammals, the brain contains
the maximum number of brain cell it will ever have at birth. Learning is
accomplished by establishing connections between various brain cells. In
birds, the number of brain cells change through out its life. In many
passerines, the brain gets bigger in the spring then cells die in the fall
(most of these cells are associated with singing). So birds can learn
throughout their lives; they do it by growing new brain cells.

Research on mimids (I think it was mockingbirds) suggests males learn new
sounds all through their lives. Females prefer males with larger
repertoires. The theory goes "The bigger the repertoire, the older the
male, the better the male because he can survive longer". So males are
under selective pressure to learn as many sounds as possible. I don't think
anyone has studied whether female starlings prefer male starlings with
bigger repertoires. I think female starlings must prefer something else
(cavity size, body size, plumage color, etc.) otherwise the males would be
better at their imitations. I'm not even sure if anyone has researched
whether only male starlings mimic. If it sexual selection (like the
mockingbirds) it should appear only in males; however, it is possible that
both sexes mimic.

The take-home message in this long ornithological monolog is:

JUST BECAUSE YOU HAVEN'T HEARD A STARLING DO *THAT* DOESN'T MEAN IT CAN'T!!!
:-))

I feel better now. Thanks for your time ;)

Deb



Deb Beutler
Department of Zoology
P.O. Box 644236
Washington State Univerisity
Pullman, Whitman Co., WA
dbeutler at wsunix.wsu.edu