OSU Researchers Hunting for Dead BirdsTue, 05 May 2015 12:28:16 CDT
Windows are beautiful. They allow natural light into your home or office building, add beauty to the appearance of the structure and allow whoever is inside to feel like they are outside.
Many people dream of owning a home with walls full of windows or working in offices with windows allowing a glimpse of the outside. However, their dream is a nightmare for birds flying in the area.
“The estimated annual number of birds killed by building collisions is 599 million in the United States and 25 million in Canada,” said Corey Riding, graduate research associate in Oklahoma State University’s Department of Natural Resource Ecology and Management. “This is more than the number of birds killed by collisions with vehicles, power lines, communication towers and wind turbines combined. So, collisions with buildings is a significant conservation issue for birds that requires additional attention.”
Because collisions with buildings are the second largest source of human-related direct mortality for birds in North America (behind free-ranging cats), Riding joined Scott Loss, NREM assistant professor, and Tim O’Connell, NREM associate professor, in an OSU field study contributing to a continent-wide collaboration study among nearly 30 universities.
O’Connell began daily monitoring at the Noble Research Center, a four-story building, full of windows and glass facades on the OSU-Stillwater campus, more than five years ago. Loss began checking six other buildings on campus in 2013. With the addition of Riding, his field tech Kaitlin Emerson and his team of undergraduate volunteers, 15 total buildings, both residential and commercial, on and off campus, are being monitored 6 days to 7 days a week.
Over a 13-week combined period, the researchers have found 54 window-killed birds, 48 of which were on the OSU main campus. Another 10 birds have been found that had collided, but were only stunned.
In addition to regularly monitoring buildings, the researchers also will experimentally place already dead birds to see how long they last before being removed by scavengers on campus, such as cats and raccoons. They also will temporarily erect game cameras around some campus buildings to document which scavenger species most frequently removes the birds.
“So, if you see a camera in bush or a small dead bird on the ground, just leave it be, as it’s a part of the first-of-its-kind research project,” Riding said. “We are always looking for more volunteers to help with the carcass surveys, too.”
He gave three potential reasons why birds collide with windows.
“First, birds don’t see exactly how we do, so glass surfaces may be less obvious to birds than they are to us,” he said. “This may be exacerbated by the high-speed movements necessary for birds to maintain flight.”
Second, many birds have little experience flying near windows, particularly during their first migratory event.
“Birds reared in open grasslands, tundra, large forests and deep swamps may only encounter windows during migration as they pass through areas withhuman developments,” Riding said. “They may not recognize the potential danger of an object with which they have no experience and that they have a difficult time perceiving.”
Third, less commonly, a bird will intentionally fly toward a window when it sees its own reflection.
“This largely happens with territorial males during the breeding season who think that they have encountered another male in their territory,” he said. “In attempting to be aggressive toward the perceived interloper, the birds may collide with the reflective surface.”
Whatever the reason, it is a growing trend as the human population grows and more buildings are erected. While high-rise buildings have higher kill rates, it is the low-rise buildings and residences that account for a much larger total number of birds killed, due to a much higher quantity of structures.
“If homeowners have transparent windows, the most effective measure is to close the drapes or blinds,” Riding said. “Reflective windows, which are less common in homes, require an external covering, like a shutter. Keeping screening material over windows that open also is highly effective for the portion screened.”
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