North America has more than a billion fewer birds than it did 40 years ago, with the snowy owl (Bubo scandiacus) and the chimney swift (Chaetura pelagica) just two of the better-known species in dramatic decline across the continent, a recent survey has found. 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. Dozens of species lost more than 50 per cent of their populations between 1970 and 2014, from the obscure Sprague’s pipit (Anthus spragueii), the oak titmouse (Baeolophus inornatus), the bobolink (Dolichonyx oryzivorus)) to the familiar. Snowy owl populations, for example, fell 64 per cent in that time. Even relatively abundant birds are dwindling in number, the report says. Chimney swifts, field sparrows (Spizella pusilla) and short-eared owls (Asio flammeus) are among the common species that have lost more than half of their populations since 1970 and are expected to lose half of their current level in 40 years or less. Two groups of birds have been especially affected: grasslands species, which have been hurt by the conversion of their habitat into farmland, and insect eaters such as swallows and flycatchers, whose decline is less obvious but may be a result of falling insect populations related to pesticide use.
Source: The Globe and Mail, September 14, 2016
https://www.theglobeandmail.com/technology/science/report-finds-north-a…
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