Where Have all the Songbirds Gone?

Songbirds fly thousands of miles to return to the northern hemisphere every spring, just as regularly as the sun comes up every morning.

Or, that's how it's supposed to be.

But the numbers of migratory birds reaching the northern hemisphere from their winter grounds in the south have plummeted in recent years.

One British study found numbers of migratory birds down by 20 percent in just four years, according to the Telegraph newspaper.

A five-year study just concluded in Vermont found 17 new species since the last time an atlas was taken, in the 1970s, but other species have dwindled or disappeared altogether, according to the Burlington Free Press.

The leader of the study, Rosalind Renfew of the Vermont Center for Ecostudies, told the newspaper: "You can think of birds as sentinels of change, a kind of alarm system about what is happening to our environment."

Some studies have found that pesticides used in Latin America are killing off songbirds such as the bobolink.

"Everyone who has looked for pesticide poisoning in birds has found it," Bridget Stutchbury, a professor of biology at York University in Toronto, told Britain's Independent newspaper. "When we count birds during our summers we are finding significant population declines in about three dozen species of songbirds."

Stutchbury also wrote an op-ed in the New York Times in which she blamed North American consumers for the problem.

"Each year, as we continue to demand out-of-season fruits and vegetables, we ensure that fewer and fewer songbirds will return," she wrote.

But pesticides in the Americas can't be blamed for the decline of birds in Britain.

"It seems as though there is a big signal emerging from all the noise -- that migrants as a group are declining -- but we haven't yet found the smoking gun," David Gibbons, of the Royal Society for the Protection of Birds, told the British newspaper the Telegraph.
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Sources:

"Volunteers complete 5-year survey of Vermont breeding birds"
Burlington Free Press (VT), April 28, 2008