Fig. 17. -- Coontail being fed to a group of penned wiid mallards. This valuable food plant, after being 
air dried, was readily eaten by mallards following its immersion in water. 
of preference for the various foods available to them. With one exception, the foods associated with the 
highest survival rates in lead-poisoned ducks were the ones usually preferred. Corn was the exception. 
In one instance, a preference shown by lead-dosed mallards for corn from a mixture containing 73 per 
cent small grains partly nullified the more favorable influence of the small grains. In another case, a shift 
of preference from corn and small grains to commercial duck pellets resulted in a higher survival of 
lead-poisoned mallards than otherwise might have occurred. Canada geese on a diet of whole yellow 
corn and duck pellets were severely affected by a dose of two no. 4 shot pellets as long as they continued 
to feed on corn, but all except one recovered when they shifted to duck pellets. Undosed control geese 
continued to feed almost exclusively upon corn throughout the experiment. 
Influence of Rate of Food Consumption. -- Measurements of the amounts of food eaten by lead- 
dosed mallards revealed that symptoms of lead poisoning failed to appear in those birds that maintained 
a normal or nearly normal rate of food intake. It was found, also, that the effect of lead varied with the 
amounts of food consumed by mallards grouped by age, sex, and history of captivity. When dosed with 
shot pellets, game-farm mallards ate more both before and after treatment than did penned wild 
mallards, and wild mallards were more susceptible to the effects of lead. The food intake of 8-week- 
old juvenile game-farm mallards greatly exceeded that of adults both before and after each group was 
220) = 
