In early September the woods are quiet. The birds, through nesting, no longer sing, but the leaves are still on the trees, damping the sounds of traffic from the roads. There’s an atmosphere of waiting.
DeCourcey operates the banding station one or two days a week, May through October. In a typical year he bands up to 1,000 birds. On this Saturday he was joined by about ten volunteers–far more than necessary, but then he’s an enthusiastic raconteur and teacher who likes to share what he knows.
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Because there are so few plants on or just above the forest floor, there’s less cover for birds. “We expect to see a positive correlation between the understory and ground-cover density and the bird population,” DeCourcey says. So far that seems to be the case. When he began monitoring five years ago the local deer population was estimated at 32 per square mile. By 1993 it had shot up to 142 per square mile, and in the summer ovenbirds and wood thrushes–both of which nest on the forest floor–had vanished. DeCourcey also found several birds that had been killed while trapped in the nets, and he speculated that deer might have begun to eat them. Last winter the deer numbers were reduced to 32 per square mile again through a culling program, and DeCourcey is waiting to see whether the birds return as the vegetation grows thicker.
Back at camp, actually a picnic table set up in the woods, the bird is taken out of the bag by Glenn Gabanski, a high school teacher who’s also a board member of the Chicagoland Bird Observatory, the nonprofit organization DeCourcey set up to support this and other bird-monitoring projects.
It’s not a new idea. The first bird bander in the Americas is generally thought to have been the great ornithologist and artist John James Audubon, who tied strands of wire around the legs of several phoebes at his Pennsylvania farm and was gratified when the same birds returned the following spring. He already knew that birds migrate, but this was his first confirmation that they might return to the same nesting territory year after year.
Many birds that thrive in the deep woods, among them wood thrushes, can’t reproduce well in small wooded areas. Small predators like raccoons and crows are more abundant along forest edges, and many woodlands in Illinois are so small that they are in effect all edge.
On a warm Saturday morning in September these concerns seem distant. We’re out enjoying a pleasant morning in the woods, watching Gabanski finish working on the Swainson’s thrush. Later in the day another 20 to 25 birds will be caught, including eight or nine species of warblers–a fair haul. But as we look at the little feathered bundle Gabanski’s holding, there’s only astonishment that a body so small can make it to South America for the winter. It’s a little hard to remember that the birds have been managing these long journeys for millennia without any help from us. As the bird wings away from Gabanski’s opened hand and flies swiftly into the shelter of the woods, I’m reminded again that it’s healthy to be guided by a certain amount of faith in what the natural world does when we’re not looking.
