
A study led by Dr. Kenneth Rosenberg published in 2019 found that North America has lost a net of 2.9 billion birds since 1970, 29% of birds, and a study from 2021 found similar declines in Europe. A loss of biodiversity on this scale could have wide ramifications. The largest causes of declines are human, but there are things individuals and cities can do to be more bird-friendly.
The birds being hit the hardest include sparrows, swallows, wood warblers, and blackbirds, but in total just over half of all North American bird species are experiencing population declines. The biggest causes of mortality include domesticated cats, window collisions and pesticide use.

Birds play a number of vital roles in the ecosystem, from pollination, to pest control and seed dispersal, so their losses could have widespread impacts.
Some cities are addressing this problem head on. Nature Canada has listed five cities as bird friendly, including Calgary. Aly Hyder Ali, who works for Nature Canada’s Bird Friendly City Program explains.
“Any city that is working to become bird friendly, they’re standing at the forefront at addressing biodiversity declines within their municipal boundaries. They’re working to help reverse biodiversity declines, bird biodiversity declines, and encouraging restoring urban nature,” Aly Hyder Ali says.

The City of Calgary has been working to address the situation including bylaws prohibiting roaming cats, spaying and neutering feral cats, and releasing bird-friendly urban design guidelines to build a more bird-friendly city.
Additionally, the Calgary Migratory Species Response Team was formed in 2019 to look into causes of bird mortality in the city.
But cities can’t do it all alone. Individual action is necessary to curb biodiversity losses in addition to municipal efforts.
Sara Jordan-McLachlan is a member of Bird Friendly Calgary, and works with the Calgary Migratory Species Response Team. Jordan-McLachlan shares a few simple things people can do to be more bird friendly.
“Whether it’s by keeping your cat supervised outside, making sure your windows are covered, making sure you’re turning your lights off at night or encouraging using native plants in your garden. These are all simple things that individuals can do.”