An immature bald eagle was sighted last week at Saganashkee Slough in the Palos forest preserves. Palos is the most likely place in Cook County to find a bald eagle. The forest preserves are big enough to provide them with secluded roosting trees, and the many shallow lakes and sloughs are prime hunting areas for them. The only bald eagles on my own Cook County list are an adult and an immature I saw in the Palos preserves at the Little Red Schoolhouse Nature Center in 1982. If we ever got really lucky and had bald eagles nesting in the county, Palos would almost certainly be the place they would choose.
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Elsewhere in Illinois bald eagles were easy to find. Robert Ridgway, writing in 1889, reported that “along all the larger water-courses in our State the Bald Eagle is a more or less common bird, and may be met with at all times of the year.” They stayed fairly easy to find until the late 40s, when DDT began to take its toll.
Birders can get wildly excited about seeing nondescript little brown birds. If a Brewer’s sparrow showed up in Chicago, people would drive hundreds of miles for a look at it, yet no one who wasn’t deeply involved with bird-watching would be the least bit interested. But bald eagles are easy to appreciate. Any bird with an eight-foot wingspan commands attention, and that fierce raptorial beak adds to the overall impression.
Actually bald eagles are extremely opportunistic in their feeding habits. They do fish for themselves. They hover over the water just as ospreys do and dive on anything they see. They also are very effective hunters of waterfowl. An eagle will swoop low over a flock of ducks or coots, terrifying them into flight. If one bird becomes separated from the flock, the eagle immediately concentrates on it, sometimes overtaking it in flight, sometimes hovering overhead until the prey has exhausted itself with repeated attempts to escape by diving.
Guns started the decline of the bald eagle in North America. Farmers believed that eagles killed lambs, chickens, and other domestic stock. And a lot of people shot them just for fun. As recently as ten years ago illegal shooting was the largest single known cause of death among bald eagles, although the prevalence of shooting had declined during the 70s.
By the early 70s only two populations of bald eagles remained in the lower 48 states: a sedentary flock in Florida and a migratory population in the upper midwest. Since DDT was banned in 1973, the birds have been making a comeback. There are more of them in the Rockies now, and the upper midwest population is growing. Many of the birds that nest in Minnesota, Wisconsin, and Michigan winter in Illinois. They gather around the dams on the Mississippi and Illinois rivers where the water remains ice free. Some of these birds began to stay through the summer in the late 70s. In 1982 Jo Daviess County in the northwestern corner of the state was the site of the first known nesting in the state since 1943. Since then, successful nesting has taken place at Crab Orchard National Wildlife Refuge and Horseshoe Lake, both at the southern end of the state.
