The once-endangered bald eagle is continuing its remarkable comeback in Illinois, with a 42 percent increase in this winter’s population.
The Illinois Natural Resources Department counted a record 2,459 bald eagles in the annual mid-winter survey. Last year’s count was 1,733.
Weather helps determine where eagles congregate, so Illinois’ high count might be offset by low counts elsewhere.
Nevertheless, the count probably reflects “a generally increasing trend nationwide,” said Sue Lauzon, executive director of the state’s Endangered Species Protection Board.
In the long term, Illinois bald eagle populations are increasing about 17 percent per year and doubling every five years.
In Illinois, 79 percent of the winter eagles were seen along the Mississippi River, 16 percent along the Illinois River, and 5 percent elsewhere.
Most eagles that winter in Illinois return in warm weather to the Upper Midwest and Canada. But a growing number are staying. Last year, there were twenty active nests, which produced twenty young birds, and new nests already have been spotted this year.
Bald eagle populations began plummeting after World War II, and by the early 1970s there were fewer than 800 left in the lower 48 states.
The main reason for their comeback was the 1972 banning of DDT, a pesticide that caused fatally thin eggshells.
Eagles also had been killed while landing on high tension wires. Each of a bird-‘s wings would touch separate wires, completing a circuit and electrocuting the bird. Utilities now space wires farther apart than an eagle’s wingspan.
A third factor in their recovery was a tough law against hunting.
The eagle is one of only a handful of species that have recovered enough to come off the federal endangered species list. Others include the American alligator, brown pelican, and palau dove.
The bald eagle remains on the federal list of threatened–rare but not yet endangered–species.