Each year 22 million birds die from colliding with residential windows across the country, concludes a University of Alberta survey.

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Study says poorly placed bird feeders lead to more collisions with windows. (Canadian Press)

The study, published in the journal Wildlife Research, also suggests bird feeders and large bird-friendly trees compound the problem.

"In many cases people who go out of their way to help birds by putting up feeders and bird friendly plants are unwittingly contributing to the problem," said researcher Erin Bayne.

The research showed collisions were not random, with the highest collision and mortality rates at rural residences with bird feeders followed by rural residences without feeders.

In the city, yards with feeders claimed the most bird lives as well, especially in older neighbourhoods where there were older and larger trees.

Bayne and a University of Alberta biology class used an online survey to recruit 1,700 homeowners in the Edmonton area.

Many people recalled bird strikes 

While many people recalled bird strikes at their homes, there is little awareness of how residential window deaths might affect bird populations, he said.

The data projects that about 180,000 birds die each year after crashing into windows of homes in the Edmonton area.

Applied to national housing statistics, the research suggests 22 million birds are killed each year across the country.

Moving feeders closer or further from windows may help, said researchers.

"A feeder three to four metres from a window is bad because the bird has space to pickup lots of speed as it leaves the feeder," said Bayne.

Fast-flying birds like sparrows and chickadees and aggressive birds like robins are apt to collide with windows placed too close to free food, he said.

Researchers believe many window collisions are caused by in-flight mistakes.

"It’s called a panic flight; a bird startled by a cat or competing with other birds at the feeder may suddenly take flight and doesn’t recognize the window as a hazard," said Bayne.