believe

Scientists believe, for instance, that birds developed their complex language of song along with the evolution of flight: with their wings occupied with flying, birds learned to rely primarily on sound rather than body movement for communication. Communication also varies according to habitat, since where an animal lives influences how information travels between sender and receiver. For example, fish, marine mammals, and aquatic invertebrates all depend on the transmitting capacity of water for communication.

Clams, barnacles, and similar invertebrates communicate by opening and snapping shut their shells, and the resulting small sounds are amplified considerably in water. Bird species that live in thickly wooded habitats, where trees impede vision, rely primarily on sound signals to contact other birds. In contrast, birds living where vegetation is sparse are more likely to depend on visual signals, including colorful plumage that indicates a bird's age or gender. Social patterns have significant impact on communication as well. Solitary birds, having no one else with whom to communicate, may sing just one song over and over, whereas flocking birds, such as geese, use a wide array of calls. These calls communicate distinct messages to other members of the flock, from Danger and All clear to calls indicating that food is near or that the flock is about to take flight. Social patterns have a particularly strong influence on communication habits in primates. For this reason, researchers such as British ethologist Jane Goodall have been able to discover complex social structures among chimpanzees and other primates by documenting and analyzing communication transactions. Most animal behaviorists today believe that two major influences determine animal behavior, including communication. One influence is innate, or programmed by genes; the other is learned, or gained by experience. Either genes or experience can take a greater role, depending on the species and the behavior in question.