Individual bat species echolocate within specific frequency ranges that suit their environment and prey types.

The greater noctule bat switches its prey type opportunistically depending on the time of year.

Some of these predators are specialists concentrating on one particular prey type.

The proportions of these prey types in their diet vary according to the size of the fish.

Predators do not, however, eat only the most profitable prey types.

Other prey types may be easier to find, and E is not the only nutritional requirement.

The predator will start to switch to this prey type as it becomes more abundant.

Hunter-gatherers, however, may hold numerous search images, yet focus on the most profitable prey types.

Eating a second prey type helps herbivores' populations stabilize.

Other morphological changes suggest adaptations in response to the availability of larger and tougher prey types.