Danger
Monkeys and other animals make specific vocal sounds to warn others of impending danger, such as predators. These vocalizations vary by species, but each species recognizes danger warnings from other members of the species. When confronted with danger, many animals make defensive sounds in an attempt to scare the offending animal away. Cats often hiss, growl and even spit when faced with danger. Spitting does not actually release a large amount of saliva, it imitates the sound snakes make when they strike. This mimicry is a way to scare away other animals.
Territory
Many animals use sounds to establish and hold their territory. Male lions, for example, roar to inform other lions of their location within their territory. These roars can be heard for miles and indicate to other lions that the territory is taken. Any rivals entering the male's territory are attacked.
Mating
A common purpose for animal vocalization is to attract a mate. Species from all classes of the animal kingdom use sounds to attract members of the opposite sex, including owls, frogs, crickets and elephant seals. Mating calls typically serve one of two purposes: to attract a mate or to signal to other animals that a specific mate is taken.
Food
Several species of animals use sound when hunting, including bats, whales and dolphins. Often referred to as echolocation, these animals emit high-pitched sounds that cannot be heard by the human ear. These sounds bounce off nearby objects indicating position to the hunting animal. Other animals use sounds to alert others of food nearby.
Non-Vocal Sounds
A wide variety of animals use sounds made by their bodies to communicate in addition to vocalizations. Elephants call their calves by slapping their ears against the sides of their heads and male gorillas beat their chests to show dominance. Some animals slap their hind legs against the ground as a warning, including kangaroos and rabbits. Rattlesnakes use the rattle on the tip of their tail to warn predators away and beavers slap their tails against the water to scare predators.