Bird numbers plummeting
Audubon study finds 'disturbing' decline in IllinoisBy John Biemer
Tribune staff reporter
Published June 15, 2007
Populations of several Illinois birds nose-dived over the last 40 years -- particularly grassland species once abundant in "The Prairie State" -- as their habitat was lost to development and the conversion of family farms into industrialized agriculture, according to an analysis released Thursday by the National Audubon Society.
The Illinois trends, which Audubon called "disturbing," matched those of many birds nationally. But "in some cases it's far worse" and should serve as a wake-up call, according to Justin Pepper, deputy director of Audubon-Chicago Region.
"These are the birds of our back yards and nearby forest preserves and they're in trouble," said Judy Pollock, director of bird conservation for Audubon-Chicago Region.
The analysis was the first of its kind for the environmental non-profit. The group pulled together 40 years of bird population data collected by thousands of volunteer "citizen scientists" in its annual Christmas bird count and combined it with breeding bird survey data from the U.S. Geological Survey.
The goal was not to identify the nation's most endangered birds, but common ones with the most rapidly declining populations.
They highlighted the impact of disappearing and deteriorating habitat as opposed to more recent blights on bird populations, such as West Nile virus, which has taken a sizable toll on certain species such as crows and blue jays.
The findings tell a story bigger than a few bird species because they serve as indicators of the health of entire ecosystems, said Chicago region Audubon Director Stephen Packard.
"These birds are just the tip of a melting iceberg," he said.
Declining populations among Illinois' grassland and shrub-land bird species are well-known in the scientific community and "very, very serious," according to Jeff Walk, a conservation scientist for the Nature Conservancy. But the analysis is useful "in terms of putting together a complete picture over a 40-year time interval and looking at both the nesting season and the wintering season," he said.
Audubon made note of some conservation projects in the Chicago region that have succeeded in reversing the trend -- at least in localized pockets such as Spring Creek Valley Forest Preserve in northwest Cook County, which is a series of former farming and grazing pastures that Pepper identified as becoming a "rare gem" for birds.
Alan Anderson, vice president of the Chicago Audubon Society, had monitored the site for 22 years and gradually watched species slip away. But Audubon volunteers in recent years have helped pull out buckthorn and other invasive shrubs and weeds, removed litter and seeded fields with native prairie grass.
In one area of the park, known as Galloping Prairie, bobolinks increased almost tenfold and meadowlarks increased fivefold since 2004.
"Last year was the most fantastic, because there were species I hadn't seen there in a number of years, and large numbers of them too," said Anderson, citing dickcissel and grasshopper sparrows as a couple of species that reappeared as the land was rehabilitated.
"It's a hopeful sign because it says we know what to do and, on this small scale, we're seeing results," said Pepper. "It's just as simple as providing the habitat they need."
Still, some Illinois birds will never climb back to previous levels.
The state has lost more than 99 percent of its original prairie and 90 percent of its original wetland acreage to development and agriculture.
Of the top 20 declining birds identified by the society nationwide, a dozen were found in Illinois -- including the horned lark, the northern bobwhite, the field sparrow, the whip-poor-will, the common tern and the little blue heron.
The analysis found some species that have increased their populations in Illinois over the last four decades -- including wild turkeys, Canada geese, turkey vultures, great blue herons and red-tailed hawks.
Many raptors, including Cooper's hawks and even bald eagles, have rebounded after bans on detrimental chemicals and a cultural shift away from shooting hawks and owls, which once were perceived as nuisances.
"The vast majority of them have increased significantly over 40 years," Walk said. "These birds are doing very, very well now."
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