Not all plants are equally nutritious, and some contain distasteful or even 34 substances. Even grazing animals that need only abundant grass do pick and choose which patches are most worth 35 and pay considerable attention to signs that food is available from particular plants. Active predators face more obvious challenges because they must not only locate but capture prey animals that seldom wait passively to be eaten but devote considerable effort to avoiding that fate. [In this context, what word should replace the blank?]