Fall migration brings many surprises. Today at the Cub Run RECenter
(Chantilly, Fairfax county) I found a single flock of over 200 Brown-headed
Cowbirds. It was unusual for 2 reasons.
One, eBird flagged it for the large number, and I'm not surprised. I was
amazed to see them all in one place. Well actually two places. Half were in a
grass strip separating parking lot lanes; and the other were maybe 40 meters
away, in grass at the edge of the lot.
I studied the flock carefully, and that brought up reason #2. There was not a
single member of any other species, in either half of the flock. I'm used to
seeing big migrating groups of mixed Starlings and Cowbirds, and often there's
some Grackles, and/or a few Red-winged Blackbirds. Here's the checklist. The
Starlings listed were not part of this flock.
http://ebird.org/ebird/view/checklist/S39322405
I have been seeing lots of young and adult Starlings recently, and ditto
Grackles, so I'm pretty familiar with them; so I'm sure I was not seeing any of
them in this flock. Very unusual in my experience, a pure-species Cowbird
flock. The count is conservative - there were at least 250, maybe 300 birds
present.
Steve Johnson
Fairfax, Virginia
