Boats is entirely correct. There was never any doubt that DDT and related compounds were very largely responsible for the decline of bird and fish-eating raptors. They were solely responsible for the near disappearance of other fish-eating birds - the Pacific coast brown pelican was nearly gone, egrets and herons had been decimated due eggshell thinning from organochlorine pesticides. All those birds gradually became abundant again after the ban.
I rarely weigh in here on the lead issue because people get so upset about it. However, there is absolutely no doubt that ingested lead killed huge numbers of waterfowl and still kills many scavenging birds, which include eagles as well as vultures and condors. This is not a recent issue - fifty years ago a game warden on Sauvies Island outside Portland OR told me of picking up hundreds of 'green-asses' every year, ducks that had starved because ingested lead prevented them from digesting food, which just ran right through them and stained their vent feathers green. Of course the anti-hunters exploit this issue, but that does not make it 'junk science' - there has been unanimity about this among wildlife biologists and toxicologists for decades. I love my old guns and hate steel shot but facts is facts.
