Lead poisoning in ducks is caused from leaden pellets of shot in the gizzard. These are picked up with other particles of grit from the marginal shallows of water, in areas that have been shot over by hunters. A paralysis of the gizzard and that part of the digestive tract just in front of it, prevents food from passing through the body. The bird wastes away from starvation and becomes so emaciated that it is literally skin and bones. It is possible that some of the more vigorous birds are able to carry the lead shot and survive. Many of the specimens of sick ducks examined were found to have a large number of parasites. This may have been a contributing factor in reducing their vitality beyond a point that could withstand the lead poison.
Proceedings of the Iowa Academy of Science
©1940 Iowa Academy of Science, Inc.
Stiles, Bruce F.
"Lead Poisoning in Ducks of Southwestern Iowa During the Winter of 1938-39,"
Proceedings of the Iowa Academy of Science, 47(1), 397-399.
Available at: https://scholarworks.uni.edu/pias/vol47/iss1/98