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From: grm@piggy.UUCP (G.R.MAHLER)
Newsgroups: net.rec.birds
Subject: Re: What is this bird? (Chicago area)
Message-ID: <312@piggy.UUCP>
Date: Tue, 26-Feb-85 14:20:34 EST
Article-I.D.: piggy.312
Posted: Tue Feb 26 14:20:34 1985
Date-Received: Thu, 28-Feb-85 12:48:06 EST
References: <620@tty3b.UUCP>
Organization: AT&T Bell Laboratories - Holmdel, NJ
Lines: 31

It sounds like brown-headed cowbird is the correct identification.
There is no reason not to begin expecting some cowbirds to be arriving
in the Chicago area at this time (especially if you have recently had
a few days of mild weater as we've been havin in NJ) Actually I would expect
that you might even have a small numer of this species overwinter in your
area. The maps in the field guides have to be interpreted with a bit
of care. Arrival dates have to be tempered by a number of factors such as
local and regional weather patterns. The dates represent an "average" for
the major influx in a "typical" year. Also a small percentage of the birds
of a particular species might not have read the book - (i.e. there are
always a few oddballs - this is one of the things that makes birdwatching
interesting - stange birds may show up at strange times or places)

Yes manerisms are a valid identifying feature in many instances. Plumage
is not always the only way to identify birds (in some cases - e.g. the
Empidonax flycatchers - voice in almost required brefore a certain 
identification can be made ). Posture, speed of movement, swaying or bobbing
movements, walking vs. hopping, crawling on treetrunks/upwards (brown creeper)
vs. crawling on treetrunks/head downwards(nuthatches), feeding practices,
speed of wingbeats, depth of wingbeats, and many many other mannerisms 
are important features of the identification process.

Yes starlings do have white tipped featers in winter plumage. These are
obtained in the post-breeding moult (fall). The white spots dissapear
as winter progresses due to feather tip wear. The spring "plumage" without
the white spots is not the result of an additional moult.

                                     Glenn Mahler
                                     AT&T Bell Labs
                                     Whippany, N.J.