North America has more than a billion fewer birds than it did 40 years ago, with the snowy owl and the chimney swift just two of the better-known species in dramatic decline across the continent, a recent survey has found.

The Partners In Flight report concludes that urbanization, growth in agriculture and possibly even climate change have driven the decline in North American landbird populations, a category that excludes ducks and other waterfowl.

The total number of continental landbirds stands at about 10 billion, down from about 11.5 billion in 1970. The study’s authors – a range of academic, activist and government bodies in Canada and the United States – list 86 of North America’s roughly 450 breeding species as vulnerable, with some populations expected to be halved in a matter of decades.

“I don’t want my grandchild to go out in the forest and not hear the songbirds in the spring, and that seems to be where we’re headed right now,” said Andrew Couturier, senior analyst at Bird Studies Canada and a co-author of the report, which was released in August.

As “North America’s bird nursery,” Canada has an added responsibility to conserve habitat, Mr. Couturier said. A majority of the continent’s birds are hatched here, before migrating south.

Keeping forests musical is not the only reason healthy bird populations are important, he notes. The creatures also provide “ecosystem services” such as pollination and insect control.

And birds are often a bellwether of broader ecological health, said Judith Kennedy, head of the migratory bird conservation unit at Environment and Climate Change Canada, and a co-author of the report. She noted that sickly birds were an early warning sign of the environmental damage caused by the pesticide DDT a generation ago…CONTINUE READING