Day-to-Day Losses. -- Although local outbreaks of lead poisoning in waterfowl appear alarming, 
actual known losses in any one year have been but a small fraction of the total waterfowl population. 
Greater waterfowl losses from lead poisoning have been thought to lie in the dispersed, day-to-day 
mortality that usually goes unnoticed in the extensive areas utilized by waterfowl. 
It is possible to make an evaluation of the extensive day-by-day mortality from lead poisoning by 
(1) determining the incidence of ingested lead shot in fall waterfowl populations, fig. 9, and (2) ex- 
perimentally evaluating in wild waterfowl populations the mortality resulting from various administered 
doses of pellets. 
Fig. 9. -- A fluoroscope unit used as an aid in determining the incidence of ingested commercial shot 
pellets in live-trapped waterfowl. Ducks were placed in the cone shown in the illustration and rotated 
before the fluoroscopic screen. By this method a technician could recognize and locate the position of - 
lead shot within the body of a duck. 
Proportion of Ducks With Ingested Lead. -- Examination of the gizzard contents of more than 
18,000 ducks taken by hunters revealed that the proportion of gizzards with ingested shot varies among 
regions of the United States, fig. 10. The proportion of ducks swallowing shot is greatest in the southeast 
Atlantic and Gulf of Mexico coastal regions. In the Great Plains region, where hunters are relatively 
few in number, the proportion of ducks with ingested shot is unusually low. 
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