A new study from the University of Alberta has taken advantage of crowdsourcing to figure out the best way to keep birds from flying into windows.
As a leading cause of bird deaths in Canada, collisions with windows in buildings and houses account for 25 million bird deaths every year, a problem which the study’s author, Justine Kummer of the University of Alberta, sees in need of a solution.
Her study recruited 1,300 “citizen scientists” to help gather data – by agreeing to track bird collisions around their property over an 18-month timespan and submit the data for analysis. “I had them walk around their house every day and report whether or not there was evidence of a bird hitting their windows,” says Kummer.
The results showed that homes in rural areas had a collision risk six times that of urban dwellings, while homes with tall trees were found to be 3.6 times more dangerous than those with no trees.
In an ironic twist, homeowners who sought to attract birds by putting out bird feeders were found to have increased the odds of collision by 1.7 times. “(People) hope to attract birds to their yards, so it’s kind of counterintuitive, that more birds coming to your yard means it’s more likely there will be a collision,” says Kummer, who completed her MSc thesis on the topic.
The study found that positioning bird feeders closer to windows helped to cut down on deaths, since birds leaving the feeders can’t gather enough speed to do themselves much harm. Other safe practices uncovered by the study include using blinds to minimize the reflection of vegetation in the window and to put up bird window decals – and lots of them.
“The problem with decals is people aren’t putting enough on the window,” says Kummer. “You essentially have to cover the window. People don’t want to put big black birds on their window, so they’re getting around this by using UV decals that are relatively clear to humans, but for birds it reflects light and they can better see that there is a surface there.”
Figuring out how best to cut down on bird deaths means first understanding the nature of the problem. There are two main types of bird-window collisions, according to the Cornell Lab of Ornithology at Cornell University in New York State. Daytime collisions occur because birds see landscape reflected in the windowpane and nighttime collisions happen because nocturnal birds like warblers and thrushes are lured into windows by the lights within.
The Cornell Lab advocates turning off lights in office buildings at night along with installing external shutters or extra screening or netting on the outside of windows, at least three inches from the glass so that birds can bounce off before hitting the hard surface. As well, experts suggest homeowners take a look around their property and identify potentially dangerous windows.
“Go outside near your feeders and look at your windows from a bird’s point of view,” says the group in a statement. “If you see branches or sky reflected in or through the glass, that’s what the birds will see, too.”
And, once we get the window situation under control it’ll be time to tackle that other bird killer: cats. The friendly felines, both domestic and feral, account for a whopping 200 million bird deaths in Canada each year.