DDT wasn't the culprit.
It was mostly Illegal shooting,lack of suitable habitat, and other 'factors'.
From article:
The U.S. Fish and Wildlife Service attributed bald eagle population reductions to a “widespread loss of suitable habitat,” but noted that “illegal shooting continues to be the leading cause of direct mortality in both adult and immature bald eagles,” according to a 1978 report in the Endangered Species Tech Bulletin.
A 1984 National Wildlife Federation publication listed hunting, power line electrocution, collisions in flight and poisoning from eating ducks containing lead shot as the leading causes of eagle deaths.
In addition to these reports, numerous scientific studies and experiments vindicate DDT.
U.S. Fish and Wildlife Service biologists fed large doses of DDT to captive bald eagles for 112 days and concluded that “DDT residues encountered by eagles in the environment would not adversely affect eagles or their eggs,” according to a 1966 report published in the “Transcripts of 31st North America Wildlife Conference.”
The USFWS examined every bald eagle found dead in the U.S. between 1961-1977 (266 birds) and reported no adverse effects caused by DDT or its residues.
One of the most notorious DDT “factoids” is that it thinned bird egg shells. But a 1970 study published in Pesticides Monitoring Journal reported that DDT residues in bird egg shells were not correlated with thinning. Numerous other feeding studies on caged birds indicate that DDT isn’t associated with egg shell thinning.
In the few studies claiming to implicate DDT as the cause of thinning, the birds were fed diets that were either low in calcium, included other known egg shell-thinning substances, or that contained levels of DDT far in excess of levels that would be found in the environment – and even then, the massive doses produced much less thinning than what had been found in egg shells in the wild.
So what causes thin bird egg shells? The potential culprits are many. Some that have been reported in the scientific literature include: oil; lead; mercury; stress from noise, fear, excitement or disease; age; bird size (larger birds produce thicker shells); dehydration; temperature; decreased light; human and predator intrusion; restraint and nutrient deficiencies.
http://www.foxnews.com/story/2006/07/06/bald-eagle-ddt-myth-still-flying-high/
