A quick search of the scientific literature using the terms 'lead, shot, waterfowl' turns up over 4700 papers on the subject; as I leave for Kenya in the morning, I don't have time to digest and report on the results here. One example at random, "Ingestion of Lead and Nontoxic Shotgun Pellets by Ducks in the Mississippi Flyway by William L. Anderson, Stephen P. Havera, Bradley W. Zercher, The Journal of Wildlife Management, Vol. 64, No. 3 (Jul., 2000, pp. 848-857), hardly a left wing bunny hugger journal, looked at shot in the gizzards of 16,500 ducks, and estimated that in the 1997 season, use of nontoxic shot prevented 1.4 million ducks from dying of lead poisoning, out of an estimated 1997 population of 90 million ducks in North America.
As to Ted's comment about science singing for its supper, the hunting, firearms, and ammunition industries in this country are vastly more wealthy and influential than a few bunny (or duck) huggers. They fought the lead shot issue for decades before the science simply overwhelmed their objections and forced the FWS to take unpopular action.
As I recall, the problem is small where bottoms are muddy and shot sinks below the surface of the mud. It is very bad where hard or sandy bottoms keep the shot on top of the sediments where birds find it. Thus, in some areas one did not see dying 'green asses', but in areas of hard bottoms, the problem was severe.
