Up to 22 million birds die from smacking into Canadian homes a year, suggests a new study, and bird feeders may be partially to blame.
University of Alberta biologist Erin Bayne published a study on bird collisions in Wildlife Research last week. The study, which tracked the number of birds that hit homes in the Edmonton region, suggests that about 180,000 birds died from such collisions each year. Extrapolated to all of Canada, and that works out to about 22 million.
The study also found that collisions were 1.5 to three times more likely at homes that had bird feeders compared to those that did not.
This doesn't mean you should throw out your feeder, though, Bayne emphasized — feeders help birds by giving them food.
"Birds die because of speed," he said, and there are many simple tricks you can use to get them to slow down.
Head shots
Birder Jack Dehaas said he has 12 bird feeders in his backyard just west of St. Albert.
"We have 15 to 20 different species every day," he said, including finches, nuthatches, blue jays and woodpeckers.
He's heard about three birds a week smack into his home in the last month.
"Inside the home, we hear a bang and we know what's happened," he said.
He and his wife rush out to help whenever they hear a hit, and almost invariably find a concussed purple finch by their window.
"More often than not they don't make it," he said.
Researchers had previously guessed that about 100 million to a billion birds die like this in the U.S. every year, Bayne said — a range too broad to be of use for conservationists. In 2009 and 2010, he had his students survey 1,458 homeowners in the Edmonton and St. Albert region to get a better estimate.
About 39 per cent of those owners recalled a bird strike on their home in the last year, according to the study, which works out to about two per home per year.
"We had several homes where we had people reporting 20 birds killed in a year," Bayne said — the highest was 43.
Rural homes had about two to three times more hits and deaths a year than urban ones, the study found, likely because there are more birds in the country. Homes with feeders and homes in older neighbourhoods also had more hits – again, likely because the feeders and older trees drew in more birds.
Preventing collisions
It's unclear how the estimated 22 million deaths are actually affecting bird populations, Bayne said. The study didn't track the precise species of each bird, and there are about five billion birds in Canada.
Most of these birds are smacking into windows, he continued, flying into them in a panic, mistaking reflections for trees or not realizing the windows are there.
You can reduce the chance of fatal collisions by moving your feeder, Bayne said. Putting it far from your home reduces the odds that a bird will fly into a window, for example, while putting a feeder right next to the home will reduce the space birds have in which to accelerate. Feeders two to five metres from a home tend to cause the most collisions.
"If you have a bigger yard, definitely put (the feeder) near the very far back," he said. "It's not an ideal place for watching, but it's definitely the place that's safest for the birds."
You can also use tape, streamers, decals and blinds to make windows more visible for birds, he said. One person in the study strung a tight net over his window so the birds would bounce off it.
Dehaas said he's hung pie plates in front of his windows but the birds are still hitting them.
"It's a little bit mystifying," he said. "Maybe I need a whole bed-sheet there?"
There's not much you can do to help a bird after it's hit your window, said Jim Lange, a veteran birder at Edmonton's Wildbird General Store, as they often have severe head trauma.
If the bird is still alive, Lange suggests putting it in an open box and watching it for a bit.
"In a lot of cases, the bird will just be stunned and will recover on its own," he said.
The study is available at http://www.publish.csiro.au/paper/WR11179.htm.
