silent spring research paper
He said the levels of pesticides in the environment were interfering with the bird’s basic reproduction cycles by decreasing the amount of calcium, which is a necessity for egg shells (LA Times 1967).
American scientists began to worry in April of 1969 when they were gathered at the 64th annual convention of the National Audubon Society. It was there that it was brought to their attention that the American Bald Eagle was falling to pesticides that were preventing the species from reproducing. Alexander Sprunt 4th, research director for the society said in his speech there “unless we ban DDT the American Eagle will become extinct”. He was concluding this statement from the societies eight-year study of the Bald Eagle. The study concluded that eagle eggs in pesticide-affected areas had produced no shells, but instead the researches had discovered limp and empty membranes lying throughout the forests. Since any sort of barrier did not protect the eggs, they were unable to hatch. Sprunt said that scientists had come to conclude that DDT was the sole reason for the decrease in Eagle population.
Until 1995, the bald eagle had been listed as endangered under the Endangered Species Act in 43 of the 48 lower states, and listed as threatened in Wisconsin, Minnesota, Michigan, Washington and Oregon. In July of 1995, the US Fish and Wildlife Service upgraded