Study tracks decline of 20 common birds

WASHINGTON — The populations of 20 common American birds — from the meadowlark to the whippoorwill with its haunting call — are half what they were 40 years ago, according to an analysis released Thursday.

Suburban sprawl, climate change and invasive species are largely to blame, said the study's author, Greg Butcher, of the National Audubon Society.

"Most of these we don't expect will go extinct," he said. "We think they reflect other things that are happening in the environment that we should be worried about."

Last month, a different group of researchers reported seven species had declined dramatically because of West Nile virus. The species harmed by West Nile are different from those in the new study, except for the little chickadee, hard-hit on both lists.

Many of the species listed as declining in the new study depend on open grassy habitats that are disappearing, said Butcher, Audubon's bird-conservation director.

Some of the birds, such as the evening grosbeak, used to be so plentiful that people would complain about how they crowded bird feeders and finished off 50-pound sacks of sunflower seeds in a few days. But the number of colorful and gregarious grosbeaks has plummeted 78 percent in the past 40 years.

For the study, researchers looked at bird populations of more than half a million that covered a wide range. They compared databases for 550 species from two different bird surveys: the Audubon's own Christmas bird count and the U.S. Geological Survey's breeding-bird survey in June. The numbers of 20 bird species were at least half what they were in 1967.

Today there are 432 million fewer of these bird species, including the northern pintail, greater scaup, boreal chickadee, common tern, loggerhead shrike, field sparrow, grasshopper sparrow, snow bunting, lark sparrow, common grackle, American bittern, horned lark, little blue heron and ruffed grouse.

The northern bobwhite and its familiar wake-up whistle once seemed to be everywhere in the East. Last Christmas, volunteer bird counters could find only three and only 18 Eastern meadowlarks in Massachusetts.

The bobwhite had the biggest drop among common birds. In 1967, there were 31 million of this distinctive plump bird. Now they number closer to 5.5 million.

"Things we all think of as familiar backyard birds ... they appear in books and children's stories and suddenly some of them are way less familiar than they should be," said John Fitzpatrick, director of the Cornell ornithology lab, who was not part of the study.

While these common birds are in decline, others are taking their place. The wild turkey, once in deep trouble, is growing at a rate of 14 percent a year. The double-crested cormorant, pushed nearly to extinction by DDT, is growing at a rate of 8 percent a year, and populations of Canada goose increase by 7 percent yearly.