Hi Tweets,

For the last 3 years or so, I have been collecting
people's observations about predatory behaviour in
crows. More specifically, crows that have learned to
force birds to fly into windows. I could hardly
believe it the first time I saw it happen, but after
watching it occur more than a dozen times, I am
convinced that atleast some crows have a "system"
which they use for chasing birds into windows.

When I have seen this happen, I can usually predict
about when the chase is going to start because each
bird involved usually takes a "post" in a spot, and
plays a specific role in the action, usually coming in
to sut off a possible escape route for the fleeing
bird. Before I get flamed, let me just say now, that
these have just been my observations as someone
sitting in a room with the windows, and I was not in a
position to stop what was going to happen. After four
or five birds have taken there posts (often these
posts are in the same spot time after time) one bird
starts the action by surprising one of the robins or
varied thrushes feeding on the ground under the
madrone trees where I have seen this happen. Another
bird quickly comes in from above so that the robin
can't fly upward, but is instead caught in a
tail-chase. Another crow will then usually some in
from one of the trees along the stree and cut-off one
of the side escape routes, and yet another crow will
come in from the side and well ahead of the robin, to
cut-off the possibility of trying to out-run a crow by
going in that direction. Invariably, the robin is
forced to go to the other side, and hits one of the
windows along the building.

I'd be interested in hearing from any of you which
have seen crows chase birds into windows, and would
like to hear if you have noticed any pattern in their
attack strategy, time of day, location etc.

Michael Dossett
Bothell
Phainopepla at yahoo.com
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