In field tests of optimal diet theory, it is impossible to control the rate at which the subject encounters prey types. When tested in a laboratory with appropriate controls, however, Krebs and his coworkers (1977) found that when large mealworms were made more plentiful, in contrast to the model's predictions, his bird subjects
A) consumed small and large prey in direct proportion to their presentation rates.
B) immediately excluded smaller prey from their diet.
C) never completely excluded smaller prey from their diet.
D) tended to exclude large prey items from their diet.

Question

Quizplus · Accepted Answer

Krebs and his coworkers found that even when large mealworms were made more plentiful, the birds did not completely exclude smaller prey from their diet, which contrasts with the model's prediction that they would focus on the more abundant, presumably more rewarding prey. This suggests that the birds' foraging behavior is more flexible and less strictly governed by the immediate abundance of prey types than optimal diet theory might predict.

In Field Tests of Optimal Diet Theory, It Is Impossible