“Bird drain” (Avian apocalypse)



A study of North American bird populations appearing in the journal Science this fall set off alarms about an impending avian apocalypse. But while most of the numbers in the study were strictly correct, mitigating factors make the likely scenario far less chilling.

Cornell conservation scientist Ken Rosenberg led the study, which found that since 1970, the North American bird population has declined by nearly 30 percent, a net loss of around 3 billion feathered flyers.

While the numbers were concerning, Slate’s Michael Schulson talked with experts who analyzed the statistics and found them to reveal a less dire situation than what the media had portrayed.

Writing for Dynamic Ecology, University of Maine ecologist Brian McGill expressed general approval of the article and its findings, but still doubted if the numbers warranted the anxious response. McGill noted that many of the vanishing birds belong to species not native to North America. This is especially important, McGill said, since, “land managers and conservation agencies have spent a lot of money to drive down or eliminate invasive species.” In other words, the numbers suggest that conservation efforts are working, not that birds are declining at an unsettling rate.

McGill also pointed out that species which prefer farmland once had their numbers artificially boosted by the clearing of forests and the destruction of prairie land. Hence, the decline is likely a return to a safe, thriving level, not a harbinger of doom.

Additionally, McGill writes that the species that account for the majority of the dip are among the most abundant bird species in North America. While the numbers are a cause for concern, they don’t necessarily suggest an ongoing extinction event.

University of Minnesota conservation biologist Todd Arnold agreed. “If you take away the 40 biggest decliners from the data set, then what’s left behind is hundreds of birds, some of which are declining, some of which are increasing,” he said. “But, on average, the increases outweigh the declines.”

Manu Saunders, a postdoctoral researcher who studies ecology and insect populations, is an even stronger critic of the Creeping Cataclysm narrative bandied by the press. Some graphics released as part of the study would seem to suggest panic was the correct response. One such chart showed a population line plunging nearly to the x-axis, seemingly suggesting an impending extinction. Yet this eventuality is not supported by the study’s data set and does reflect the paper’s claims.

The stage for this ornithological overreaction may have been set by a previously-released and equally incorrect study that portended doom for insect populations.

McGill worries this Chicken Little approach might cause the public to place less trust in scientific reports and to ignore their suggestions to modify behavior. Even though the scientists made measured claims and  the media sounded the false alarm, people are doubtful to remember that when the bird die-off fails to materialize. Instead, the public may misattribute the panic to the scientists and give less credence to future studies.

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