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?
|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.
|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.
|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.
|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.
|a Hermit Thrush lies dead beneath Duke University's sparkling new Penn Pavillion|
...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.
|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.
|Ovenbird, a window strike victim at Duke University|
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/
If you find window strike bird anywhere in the world, you can report it to this new iNaturalist project: http://www.inaturalist.org/projects/bird-window-collisions
*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.