Animal communication is a term used to describe the process in which one animal transmits information to another animal. While some think that communication is unique to humans, the process of exchanging signals, intentionally or unintentionally, is also an integral part of the life of other animals.
Messages in animal communication can take different forms - visual, tactile, olfactory, gustatory and auditory. Movements, gestures, facial expressions and colors are all visual messages. Examples of tactile messages are touch, bumping, rubbing, vibration and other types of physical contact. For many animal species, including humans, this type of communication is vital in the relationship between the young and its parents. It is also important in courtship and intimate relations, social interaction, defense and aggression. Olfactory messages are conveyed via smells and gustatory messages via tastes. These are chemical messages - pheromones - transported by water or air. This type of communication is particularly typical for insects but it is also used by some vertebrates and even by plants. Auditory messages, or sounds, may be produced by speaking, whistling or drumming. Examples of such messages are speech among humans and vocalization among birds, primates, dogs and many other animals. Another type of messages used by some fishes is electrical impulses.
All these means of communication serve a variety of functions. Some of the most important functions of animal communication are courtship and mating, parent-offspring socialization, navigation, self-defense and territoriality. The different animal species may use different kinds of messages or combination of messages for the same function - for example grasshoppers and crickets use song in their courtship rituals, while moths use pheromones and fireflies rely on visual messages. Another vital function of animal communication is to help the parent teach survival skills and patterns of behavior to the offspring.
Animals also use communication in navigating through space in order to locate food, avoid an enemy or get to a place. Some animals, such as bats, dolphins and whales, navigate via echo-location: using sound to determine the distance and direction of an object. Another example of a unique type of navigational communication is the dance performed by social bees when they identify a desirable food source and want to communicate its location to other bees. Animals also use communication for self-defense and territoriality (marking and maintaining home territories).
According to Donald R. Griffin in The Question of Animal Awareness: Evolutionary Continuity of Mental Experience (1981), the orientation behavior of an animal can also be viewed as a process of communication with its surroundings. Orientation behavior refers to behavioral responses in animals triggered by even weak signals from the environment.
One major question regarding animal communication is whether the messages are sent intentionally or unintentionally. Some signals may simply be by-products of certain internal processes - for example, when a chick emits peep calls that attract the hen or when a human baby cries for its mother.
According to Lesley J. Rogers in Minds of Their Own: Thinking and Awareness in Animals (1997), "being aware of the vocalizations that we make is something that develops with age." This principle may also be true for animals, a theory supported by some evidence that adult chickens may communicate intentionally. If an animal tries to deceive another animal by using a call with a specific meaning in an unusual context, this may be a proof that animals are aware of the fact that they are communicating. For example, data reported by M. Gyger and P. Marler indicates that some roosters emit so-called food calls to deceive a hen into approaching.
Communication most often takes place between animals of the same species (intraspecific communication). However, interspecific communication, or communication between individuals of different species, is also typical and important in some situations. Examples of this second type of communication are prey/predator and human/animal communication.