SUMMARY 
1. Lead poisoning is likely to occur in wild waterfowl that have swallowed lead shot pellets ob- 
tained while feeding in shot-over areas. 
2. The grinding action of the gizzard and chemical action of the digestive juices erodes and dis- 
solves the ingested lead shot. Lead compounds that are formed appear to have a direct, damaging effect 
on the smooth muscles of the digestive tract, and, after being absorbed by the blood stream, a harmful 
effect on the liver and kidneys. Lead poisoning is the name given to the pathological condition that results. 
3. Ducks severely affected by lead poisoning eat little or no food and suffer marked weight losses. 
Weakness, fatigue, and exhaustion are the most common symptoms in lead-poisoned ducks. Ducks that 
die of lead poisoning are emaciated; vital organs and muscles are abnormally small, and the gizzards 
show evidence of decreased activity. 
4. Available evidence indicates that the flesh of lead-poisoned ducks can be eaten by human beings 
without ill effect. 
5. Outbreaks of lead poisoning in wild waterfowl usually occur late in fall or in winter after large 
numbers of ducks have moved to heavily shot-over areas to feed. 
6. Day-to-day losses in wild waterfowl can be evaluated by determining the proportion of birds 
with ingested lead shot, the numbers of pellets in the gizzards, and the rates of mortality produced by 
given numbers of pellets among waterfowl in a wild state. 
7. The incidence of ingested lead shot varies from 1 to 13 per cent among the different species of 
wild ducks studied. Differences in the incidence of shot among species are attributed to variations in ~ 
methods of feeding and in types of habitat preferred. 
8. Of 18,115 duck gizzards collected from many parts of the United States and examined, 5.28 per © 
cent contained ingested lead shot. Of those containing shot, 69.3 per cent contained one pellet, 13 per — 
cent two pellets, and 17.7 per cent more than two. 
9. Band returns from wild mallards dosed with shot pellets and from approximately equal numbers 
of undosed wild mallards banded and released at the same time showed that the birds dosed with lead 
shot did not fly so far as undosed birds before being bagged; also they were more vulnerable to shooting. 
10. The ingestion of not more than one shot pellet by any one duck did not appear materially to 
lower the numbers of wild drake mallards from one year to the next. 
11. Food was found to have an important influence on the effect of the lead shot ingested by | 
penned waterfowl: 
SoG= 
