Hi Paul,
Sad story. I've been researching bird collisions at wind farms at the American Bird Conservancy and the research shows a couple of factors that increase collisions:
1. Fog - can be catastrophic and a bad fog day during migration can represent +90% of bird kills for a whole year at a given site.
2. Low clouds - tend to force migrants to fly at lower altitudes creating more bird vs. ? risk
3. Strong winds - I believe I read at Woodcreeper.com that they found birds migrate at lower altitudes during strong winds.
The American Bird Conservancy is working on this issue and has developed "Bird Tape" - a mostly transparent tape that can be put on windows and retrofit an entire building!
Here's a bit of info about this issues from ABC: http://www.abcbirds.org/abcprograms/policy/collisions/glass.html
One reason you might have not found more is that many buildings with a bird collision probelm will instruct maintenance crews to clean up dead birds as early as possible in the morning.
By the way, you said you only found a head? I wonder if it was the remains of a Peregrine kill? They tend to remove the heads before eating thier prey.
Jason Berry
Washington, DC
--- On Fri, 10/21/11, Paul Pisano <> wrote:
From: Paul Pisano <>
Subject: [MDOSPREY] Building strikes
To:
Date: Friday, October 21, 2011, 1:16 PM
This week I had the misfortune of finding 2 dead birds at the base of my
office building - the U.S. DOT HQ in SE DC. The first was on Monday and
was a NORTHERN PARULA. The second was this morning and was a
YELLOW-BILLED CUCKOO. I think there were others lat night because I
found an unusual feather (secondary?) of varying shades of brown, as
well as a small mound of unidetifiable body feathers at two other spots.
The secondary? could have been from the cuckoo, but was kind of far
from the rest of the remains. Actually, the "remains" only consisted of
a head, so clearly other factors are at play here. I'm surprised that I
found both of them this week as: 1) it's getting late in the season so
the number of migrants at all is going down, and 2) these are the first
I've ever found here. Why I haven't found others earlier in the season
is unclear to me (though might have something to do with the fact that I
drive a few days a week, which doesn't have me walking along this
stretch of the building - except this week when I took metro 4 of the 5
days).
Has anyone ever recorded a pattern between building strikes and the
migration season? I'm sure that they've looked at weather, but Sunday
night and Thursday night were very different in that respect (if I
recall correctly). Just thinking out loud, perhaps later migrants are
weaker, which means they might not fly as high (and hence more prone to
hitting buildings)? I don't know, that's probably connecting dots that
don't exist, but just has me wondering. Interestingly enough, this
building is not even the highest in this area, and it not much higher
than the building immediately across the street.
BTW, this is my second dead cuckoo this fall though the other was a Ft.
Dupont as was clearly not related to striking a building.
Good birding,
Paul Pisano
Arlington, VA
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