Most birders come across a window strike victim every now and
again and perhaps think of it as a tragic freak accident. But did you know that collisions with windows
are the second leading source of human-caused bird death in the United States?
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Tufted Titmouse, a window strike victim at Duke University |
It’s a serious problem, particularly for neotropical migrants, many of
which have declined significantly in North America over the past century. It isn’t possible to attribute population
declines to collisions, but the annual death of an estimated 1 billion birds (*source below) certainly isn’t helping. And with more
and more buildings being constructed that means more windows and more chances
for fatally concussed birds.
The good news is that solutions are relatively cheap and
easy. Window panes can be coated with
ultra-violet reflective films or stickers to make them appear visible to birds without ruining the view for people. Mortality of nocturnal
migrants can be greatly reduced by turning off lights and/or shutting blinds
during peak movements. This approach has
been taken by major metropolitan areas, such as Toronto and Chicago, which have
annual “lights out” programs.
Data on the scope of the problem here in the Carolinas is
mostly anecdotal so far. Around the
campus of Duke University in Durham, NC a few birders have collected dozens of
incidentally discovered carcasses to send to the natural history museum in
Raleigh to be used as study skins.
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An assortment of window strike victims found on Duke University's West Campus over the past year |
I stumbled upon
the first campus record of a GrasshopperSparrow outside Cameron Indoor Stadium over a year ago.
Luckily this bird was still alive, confused and fluttering against a
ground-level window.
I was able to catch
it, document it with an iPhone and release it unharmed.
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Grasshopper Sparrow, a window strike survivor at Duke University |
The first campus Fox Sparrow record came a couple weeks ago, but this bird was less fortunate.
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Fox Sparrow, a window strike victim at Duke University |
Both these sparrow species are relatively rare around Durham
and it is clear that buildings on campus are the cause of mortality not just to
local residents, but also to passing migrants that may be drawn into the
well-lit and reflective campus only to crash into invisible walls.
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a Hermit Thrush lies dead beneath Duke University's sparkling new Penn Pavillion |
But it will take more than the tragic story of a few birds
meeting an untimely end to sway the corporate administrators that crank the
machinery running Duke’s multibillion-dollar empire.
Deliberate sampling, statistics and
cost-benefit analyses are needed.
...which is exactly why carcass surveys began last week focusing on seven West Campus buildings. They will continue for 21 consecutive days of as part
of a project led by Natalia Ocampo-Penuela, a doctoral candidate at Duke’s
Nicholas School of the Environment, and Nicolette Cagle, a Nicholas School
instructor. Their Duke team will pool
data with a consortium of 45 other North American colleges and universities
investigating bird death from windows on their campuses. The international team includes academic
institutions in Mexico and Canada and is spearheaded by researchers at Augustana
College in Illinois. Duke is the only
participant in North Carolina.
Surveys at Duke will not only help quantify the magnitude of
the problem nationally, but also help identify local campus hot spots for bird
strikes where mitigation can have the greatest positive effect. Data on the shape, orientation, surrounding
land cover and window properties of these buildings will also help inform
future architects about strategies for bird-friendly design. Six of the buildings in the survey have
received awards for Leadership in Efficient Environmental Design (LEED
certification), but so far it doesn’t look like many are that actually that friendly to birds.
Did you know that last Tuesday night there was a big movement of migrating
Yellow-bellied Sapsuckers, an uncommon woodpecker that winters in Duke
Forest? I do because surveyors found
three dead ones around Duke buildings on Wednesday.
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Yellow-bellied Sapsucker, a window strike victim at Duke University |
Durham’s first Ovenbird of the season arrived
that night. It may have crossed the Gulf
of Mexico recently on its way to breeding grounds in Duke Forest or points to
the north. But it’s chance to breed this
year were ruined by a window of the French Family Science Center at Duke.
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Ovenbird, a window strike victim at Duke University |
This kind of practical action-oriented conservation science
that Ocampo-Penuela and Cagle are pursuing is exactly what these birds need.
For more information about this project and instructions on
what to do if you should find a window strike victim on Duke's campus, see their website:
http://sites.duke.edu/birdcollisions/
*Loss S.R.,
Will T., Loss S.S., and Marra P.P. 2014. Bird–building collisions in the
United States: Estimates of annual mortality and species vulnerability.
Ornithological
Applications 116: 8-23.