A group of Augustana College researchers hopes to deepen the understanding of why birds collide with closed windows.
Previous studies on the phenomenon were limited in many ways, said Augustana professor Stephen Hager, who led the college's research team.
"We've known birds have been hitting windows since we've been putting windows in buildings," he said.
The goal of his group's research was to collect more comprehensive data, so in2010, a dozen students and faculty members spent time each season monitoring 20 buildings in Moline and Rock Island.
They counted the number and types of dead birds found within about four feet of each building during daylight hours, the number and type of live birds they saw in surrounding areas, and measured the amount of window surface in square meters.
They found that only certain species were hitting windows, and most of them were about a year old or younger. They also usually were hitting buildings with lots of windows near sizable green space in which birds could live, said Dr. Hager, who has a Ph.D. in biology.
The body count was actually quite small -- only 34 birds from about 16 species, he said, adding that the group observed about 72 species of birds during its survey.
Among the dead birds, robins and doves were some of the more common, but no sparrows and pigeons were found, although live specimens were commonly observed during the research.
"That suggests there's a group of vulnerable birds," Dr. Hager said.
But the small number of dead birds found also suggests that window collisions, at least for the study area, may not be be as bad as people might think, he said.
Previous studies usually focused on one, two or a small cluster of buildings where dead birds were being observed, and often were done during the spring or fall, with little attention paid to other parts of the year, Dr. Hager said.
The local research group picked buildings at random rather than going where it knew it would find birds. It also looked at a variety of building types surrounded by varying degrees of development and green space.
The Augustana group factored in the likelihood of being able to find dead birds, and scavengers' potential effect on the targeted sites, to maintain an accurate count, he said.
Dr. Hager hopes to use the research to aid conservation efforts. His group already has used its data to create a tentative map for Rock Island and Moline, meant to predict the prevalence of bird versus window collisions in specific areas.
"This is the first map of its kind," he said.
To create it, the group mixed its data with local and federal records that helped them determine the potential amount of window surface and green space in particular areas. The researches collected information on 2,000 buildings in the study area.
The map is covered with blotches of red, orange, yellow, green and blue. Red indicated the highest risk areas, orange and yellow were next, then green and blue indicated areas of less or little risk of collisions.
There were only a few red spots on the map. Most of the rest was green and blue, though there was some orange and yellow.
Dr. Hager said the group has not yet tested the accuracy of the map's predictions with field observations. He wants to do at least one more round of research targeting what effect, if any, bird feeders might have on the prevalence of window collisions.
Those observations are planned for this year.
Dr. Hager said accurate maps of that nature could help conservationists around the country with efforts to protect birds. The hope is eventually to create a method that would allow researchers to create maps for specific areas across the United States.
The group's work has been published in PLOS ONE, an international, online scientific journal, according to an Augustana news release. The article is titled "Window Area and Development Drive Spatial Variation in Bird-Window Collisions in an Urban Landscape."
PLOS ONE's website can be found at http://tinyurl.com/b5sc98a.