While I remember the effect on waterfowl from ingestion being a concern when I gave up duck hunting (thats right, I said "the hell with it" when lead shot was verbotten, and shooting a redhead or a canvasback got you about the same penalty as shooting a bald eagle, about 1980 or so) the real reason was the effect on higher predators that fed on mildly poisoned ducks, which concentrated the lead in them. Bald eagles have made an impressive comeback since then, but, I dare anyone to show us how it was from banning lead shot for waterfowl hunting. Banning DDT, I might be persuaded to believe, but, lead?
Best,
Ted