Also when handling a prey, it may be exposed to other predators, so it incurs some risk during search and handling time. To account for this risk, the food must be devalued commensurate with the risk. If this were true, the animal would have an Optimal Foraging Strategy . Let's say that flies are the best prey and that worms are the next best. The best type of prey is the one which can be handled most quickly.
Abundance is in units of the number of encounters per unit of search time.
Let's compare the two potential best strategies. 1 is the average time spent searching for and capturing a fly. This is called searching time. We should see finer discrimination when prey are abundant than when prey are rare. Even if the number of prey types are increased, the theory predicts that the choice to add another prey type to the diet will depend only on the abundance of all prey types of higher quality.