Predators usually live singly or in small groups, but their prey animals often group together in large numbers.
The most important reason for this behaviour is that there is safety in numbers. A predator will often become confused by a large, rapidly shifting group of prey. For example, a tuna will find it very difficult to select one target fish from a closely packed shoal containing several thousand fish. Similarly, a lion will usually not try to catch one of a panicking herd of wildebeest, but will attack stragglers or injured animals.
Sometimes a herd has a defensive function. Adult buffalo and musk ox group together to form a protective circle around their vulnerable youngsters when a predator is near. The predator will not usually attack a fully-grown adult.
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