“Until the 1980’s, the previous recorded nest in Kentucky was in the early 1950’s,” said Lee. “We went a full 35 years without a single eagle nest in the state.” The Bald Eagle, like so many other birds, had fallen victim to the effects of DDT, a now banned insecticide in the U.S.
DDT, for a period of time, was a seemingly effective insecticide. It quickly killed the mosquitoes that spread malaria and the lice that carried typhus, and is credited with saving millions of lives. Eventually though many insects developed a resistance to DDT and produced offspring that were also resistant. DDT was also highly toxic to the fish in our waterways. A recipe for disaster was brewing.
A “persistent insecticide,” the molecules in DDT stay together as a poison for a long time before breaking down into smaller, less toxic substances. It washed deep down into the soils, our streams, and lakes. DDT became entrenched in the food chain. And because it does not break down easily, DDT builds up in fatty tissues where it persists for long periods of time. It takes an animal 8 years to metabolize one half of the DDT it consumes – more than a lifetime for many species of birds and mammals. Birds, like the Bald Eagle and Brown Pelican, ingested DDT after eating contaminated fish. The DDT caused their eggshells to be thin and brittle, so brittle that eggs were broken on the nest as parents sat on them during incubation. Eagle numbers plummeted to only hundreds of nesting birds in the contiguous U.S.
DDT was banned in 1972. “Eagles have been slowly re-establishing, especially in Western Kentucky,” said Lee. “There are also a couple of nesting pairs in the Cincinnati area, one in Brown County, Ohio and another along the Great Miami River.” According to Kentucky Fish and Wildlife, we now have a healthy population of 48 nesting pairs of eagles in the state, with another 100 to 300 over-wintering. Having been taken off the Federally Endangered Species List, things are looking up for the Bald Eagle. “They have recovered well and will probably continue to do so,” said Lee.