. Bulletin. Natural history; Natural history. May, 1959 Bellrose: Lead Poisoning in Waterfowl 255 over area, which, combined with intensive feeding by the ducks, resulted in exposure of the birds to unusually large quantities of lead. At the trapping site, lead shot was avail- able equally to the three species, and, in September, it was unlikely that the birds were obtaining shot elsewhere. Yet, among the species, there were differences in incidence of ingested shot, table 7. Pro- portionally more pintails than wood ducks and proportionally more woodies than blue-winged teals carried ingested
. Bulletin. Natural history; Natural history. May, 1959 Bellrose: Lead Poisoning in Waterfowl 255 over area, which, combined with intensive feeding by the ducks, resulted in exposure of the birds to unusually large quantities of lead. At the trapping site, lead shot was avail- able equally to the three species, and, in September, it was unlikely that the birds were obtaining shot elsewhere. Yet, among the species, there were differences in incidence of ingested shot, table 7. Pro- portionally more pintails than wood ducks and proportionally more woodies than blue-winged teals carried ingested shot. Apparently, there is a relationship between the weight of a duck and its intake of food and lead. Perhaps under similar condi- tions of food and feeding, the duck spe- cies with the largest individuals have the highest percentages of individuals with in- gested lead shot, table 7. In two of the three species, table 7, an appreciably greater percentage of juveniles than of adults carried ingested lead shot; in the pintail there was little difference in shot incidence between age groups. In the pintail, blue-winged teal, and wood duck, there were only slight dififerences between the sexes with respect to inci- dence of shot, but, in the lesser scaup, pro- portionally twice as many drakes as hens carried ingested shot, table 7. The lesser scaups represented in table 7 were trapped on another area near Havana in April, 1953. The seasonal incidence of ingested lead shot among mallards trapped at the Chau- tauqua National Wildlife Refuge during the fall months of 1949 and 1950 is shown in table 8. Most of the mallard groups fluoroscoped early in the season had a. Fig. 4.—An X-ray head and fluoroscopic screen used at the Havana laboratory of the Illinois Natural History Survey to determine the incidence of ingested lead shot in wild water- fowl trapped alive as well as in dead and moribund birds picked up in the field. Each bird was placed in the cone, which was rotated in fro
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