July 12, 2004

BY GARY WISBY Environment Reporter

Black-crowned night herons in a big Far South Side colony spend the night fishing, their red eyes virtually seeing in the dark.

They spend the day being studied by scientists.

Or so it would seem, with two unrelated research projects focusing on the Calumet area birds.

One study looks at the health of the herons, which live in marshes polluted by steel plants once located there. The other examines how the birds react to human disturbance.

It's quiet now, but humans will arrive -- walking, bird-watching, perhaps cycling -- as the Calumet Open Space Preserve develops.

The disturbance study will help ensure that trails and platforms aren't placed too close to heron nests, said Patrick Zollner, who is heading the project for the U.S. Forest Service.

It will tell the researchers that, as people approach, "this far away, the birds freeze; this far away, they fly away, and they stay away for this long," he said.

To plug in the numbers, scientists and students in canoes are bothering the birds with a boom box. They play a four-minute tape that includes teenagers playing basketball, a family talking at a festival and kids singing.

They vary the volume -- high and low; the distance -- far, close and closer; and the frequency -- some nests are visited twice as often. This goes on four hours a day at the rate of 14 nests a week. Nests in a control group are left alone.

Research last summer by Zollner's top aide, Esteban Fernandez-Juricic of California State University at Long Beach, showed that several bird species ate less "because they were spending so much time stopped, watching for tourists," Zollner said.

Begun in May, the study will continue through next year. The other study started in 2002 and wraps up in December.

Its leader, Jeff Levengood of the Illinois Natural History Survey, is still "wading through gobs of data" but has concluded that the herons are in good shape despite their contaminated nesting ground.

Comparison of their eggs with heron eggs from Minnesota and Virginia showed the Illinois birds had much higher levels of DDE, a breakdown product of DDT. "But we don't see any dramatic impacts," Levengood said.

The herons appear to be tough and tolerant. Their colony here and one in East St. Louis -- both with 300 to 400 nesting pairs a year -- are the largest in Illinois although both are in environmentally blighted areas.