Conservationists try to lure back ospreys

BLOOMINGTON, Ill. -- Bird enthusiasts have erected nesting platforms to attract a rare species of fish-eating raptors to three lakes in McLean County.

Osprey migrate through Central Illinois and they have been seen this year at Evergreen Lake and Lake Bloomington north of the Twin Cities, said raptor expert Given Harper, who chairs the biology department at Illinois Wesleyan University.

But most ospreys, which are on Illinois' endangered species list, merely pass through the state on their way to summer homes as far north as Alaska, or wintering grounds in Central and South America, he said. The Illinois Department of Natural Resources has documented just four currently active osprey nests in the state, according to IDNR's Randy Nybor.

Harper said three or four years may pass before adult birds use the platforms to lay eggs and rear their young. But if the project flies, organizers from the John Wesley Powell chapter of the Audubon Society hope more platforms will be erected elsewhere in Illinois.

"This is pretty exciting," Harper said. "If we are successful here, we would advocate that other nesting platforms would be installed at other reservoirs across the state."

Effects of DDT

The ospreys' presence will have minimal impact on fish populations, he stressed.

Like bald eagles, osprey numbers were decimated by DDT, a now-banned agricultural chemical that washed from farm fields into America's waterways. Once the substance entered fish, it traveled up the food chain and disrupted the ability of raptors to reproduce.

The nesting platforms at Evergreen, Lake Bloomington and Dawson Lake at Moraine View State Recreation Area near LeRoy are perched about 30 feet in the air atop utility poles donated by Corn Belt Energy and installed by workers from the International Brotherhood of Electrical Workers on their off-hours.

The U.S. Fish & Wildlife Service provided one platform. Dale Birkenholz, professor emeritus of biology at Illinois State University and a bird expert, built two others. All have wooden sticks in place to create the illusion that ospreys used the platforms in the past. The hope is the trick will convince a mating pair of ospreys the platforms are safe so they stay to raise their young, Harper said.

The months of April and May are peak times for ospreys to appear in Central Illinois, Harper said, but some also are seen in fall as they migrate south.

The effort is an extension of other programs to encourage birds not often seen in the region to establish local populations.

The JWP Audubon Society and ISU joined together earlier this year to install a nesting box for peregrine falcons on the roof of Watterson Towers, where peregrines have paused in the past during spring migrations. Some individual birds have stayed up to several weeks apparently waiting in vain for a mate.