The best behaviour that an individual can perform in the given circumstances, in accordance with particular optimality criteria. For example, crows (Corvus) hunting for whelks at low tide usually select the largest ones. They then hover over a rock and drop the whelk so that it breaks open, exposing the edible inside. The number of times a whelk has to be dropped in order to break is related to the height of the drop. The crows have to expend energy in flying up to drop a whelk, so what is the best height for the crow to fly? In other words, what is the optimal behaviour—to make many low flights, dropping the whelk each time, or to make few, higher flights? Given that the aim of the exercise (the optimality criterion) is to break open the whelk while expending the least amount of energy, it turns out that the optimal behaviour is for the crow to drop the whelk from a height of 5 m, in which case it may have to make about five attempts, performing a total amount of upward flying of about 25 m. For heights smaller or greater than 5 m, a larger amount of total upward flying is required.
Subjects: Zoology and Animal Sciences.