Bob and Karen Fisher of Downers Grove count hawks during the birds' migration south and report their findings to hawkcount.org, a site that compiles data from all over North America. (Michael Smart, Chicago Tribune)
The avid birders perch in lawn chairs at the Greene Valley Forest Preserve's 190-foot overlook near Naperville, their eyes peeled for hawks migrating through a "blue dome" — a cloudless sky.
In a perfect world, Downers Grove birder Bob Fisher said the birds would be flying directly overhead, a few clouds would make it easier to spot and count them, and a north wind would gently push them south for the winter.
But on a recent day the clear sky made it difficult to see birds, some flying one or two miles above. That didn't deter Fisher, his wife, Karen, and other birders from scanning the skies with their binoculars to monitor the hawk population during this, their peak migration season.
The Fishers and other volunteers are on duty 10 a.m. to 2 p.m. daily from September through November at the overlook atop a retired landfill. The Greene Valley hawk watch station is one of 200 in the U.S., Canada and Mexico, and two in Illinois (the other is in Zion).
Sometimes they rise to "a good hawk day." On Oct. 7 watchers counted 202 hawks and other raptors. Other times it's fewer than 20.
The Fishers try to be on the hill every day. And each evening Bob relays the latest data to the Hawk Migration Association of North America.
"Hawk watches are important because increases or decreases in the numbers of individual species can be shown ... each year," said Illinois Natural History Survey ornithologist Steve Bailey. Sharp-shinned hawks, for example, are declining in numbers, but most raptors are holding their own, he says, and Cooper's hawks are increasing in number. Hawks can be a barometer for environmental problems, Bailey adds, as they were when the negative impact of DDT was discovered years ago.
The Greene Valley watch was started by the Fishers and others eight years ago. And the Fishers are its "heart and soul," said Vicky Sroczynski, who adds that being on the hill is a reminder of the "larger, more amazing processes happening every day on Earth."
Bob Fisher said identifying hawks is a learned skill, but the duty sometimes is "pretty miserable ... really nasty in mid-November." But the birders have a panoramic view of the fall colors. And they've witnessed the movement of 25,000 sandhill cranes and a major dragonfly migration.
"It can get pretty boring," Karen Fisher said. "It also can be pretty spectacular."