I have been monitoring building strikes at my work place in Anne Arundel
since 1991.  It is, indeed, a largely seasonal problem.  Fall and spring
are the seasons.  I don't have numbers handy, but it's been about 70
species, and a total of over 500 over those 20 years.  We crossed the 100
threshold for Ruby-throated Hummingbird this season.  Next most abundant
with White-throated Sparrow or Dark-eyed Junco in second place in the high
30s.

Fall has at least 2X more strikes than spring.  Most appear to strike
overnight, or at least are present at dawn.  And the buildings are
oriented to the south, so I don't think it's migrants per se that are
being intercepted.  My suspicion is we're getting the birds after they've
settled down from migration and are now going out for breakfast.  The
hummingbirds, however, overwhelmingly strike in daylight.  The building is
green, reflective glass high-rise.

This week's only casualty was a Myrtle Warbler, who apparently survived
with only a big headache.  Last week was another story:  1 Swainson's
Thrush, 2 Magnolias, 2 Black-throated Blues, 2 Pine, 1 Tennessee, 1
Wilson's, 1 that flew away before I could get a bead on it, and a mystery
smallish sparrow (Chipping?), that was out of reach and also was able to
escape before I could get a good identification.

I hope when I retire in the next few years to sit down with these numbers
and come up with something to publish.

Clear weather is the most deadly, but fog can be interesting.

You can read lots more scientific stuff about this at

COLLISIONS BETWEEN BIRDS AND WINDOWS: MORTALITY AND PREVENTION
http://birdscreen.com/PDF/Klem_AFO_Collisions1990.pdf


Lights Out Baltimore!
http://mysite.verizon.net/vzeedyar/lightsoutbaltimore/


Fatal Light Awareness Program
http://flap.org/flap_home.htm

If you google "bird strikes klem" you will find many articles by Dr. Klem,
the authority on this subject, published in the Wilson Bulletin, and
available on-line in PDF format.

Happy Reading!

Kurt Schwarz
Conservation Chair
MOS 
goawaybird at verizon dot net

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