New research published Thursday in Science shows bird populations have continued to plummet in the past five decades, dropping by nearly three billion across North America—an overall decline of 29 percent from 1970. Ken Rosenberg, the study’s lead author and a senior scientist at the Cornell Lab of Ornithology and the nonprofit American Bird Conservancy, says the magnitude of the decline could significantly affect the continent’s food webs and ecosystems.
“We’re talking about pest control, we’re talking about pollination and seed dispersal,” he says, referring to the roles birds play in ecosystems. Because it is relatively easy to monitor birds, he adds, their presence or absence in a habitat can be a useful indicator of other environmental trends. Based on the paper’s results, he says, “we can be pretty sure that other parts of the ecosystem are also in decline and degradation.”
Rosenberg and his colleagues used data from citizen-science bird-population assessments, including the North American Breeding Bird Survey and the Audubon Christmas Bird Count, to estimate changes since 1970. In these yearly projects, thousands of volunteers perform “point counts,” tallying all the birds they can see and hear in a short time period at locations along designated routes.
