by Gray Merriam
Avian Conservation and Ecology, a fully electronic scientific journal published by
Canadian ornithologists has just published a new study showing that about 296 million
birds and 2 million bird nests are destroyed by human activities in Canada each year.
Feral and pet cats killed as many birds as all other causes combined. Feral cats caused
about 60% of that. Pet cats caused the remainder.
Collisions with electricity transmission lines were the second largest cause of mortality
—— between 10 and 41 million birds per year – – two-thirds by electrocution on lines and
one-third by clearing of vegetation under lines.
The third highest mortality rate was collision with buildings.
About 13.8 million birds are killed by collision with vehicles.
Highest rates of deaths were in areas with denser human populations.
Developments helping to reduce bird kill include special glass for tall buildings and
keeping buildings dark at night.
Birds are excellent indicators of biodiversity changes and these results will help guide
future biodiversity research and conservation efforts.