Social behavior is defined as interactions among individuals, normally within the same species, that are usually beneficial to one or more of the individuals. It is believed that social behavior evolved because it was beneficial to those who engaged in it, which means that these individuals were more likely to survive and reproduce. Social behavior serves many purposes and is exhibited by an extraordinary wide variety of animals, including invertebrates, fish, birds, and mammals. Thus, social behavior is not only displayed by animals possessing well-developed brains and nervous systems.
Benefits of Social Behavior
Social behavior seems to provide many benefits to those who practice it. Studies have shown that many animals are more successful in finding food if they search as a group. This is especially true if food resources are clumped together only in certain places. If more individuals are cooperating in the search, there is a greater chance one of them will find the clump of food. In some cases, foraging in a group makes it easier to capture a prey. Dolphins are known to surround a school of fish and to take turns darting into the center to eat the fish that are trapped in the middle. Many carnivores will band together when they try to capture large prey. For examples, wolves will hunt together when hunting moose, and lions will hunt together when hunting large prey such as wildebeests. When these animals are hunting much smaller prey, they will often hunt singly.
Many animals live in social groups partly for protection. Although one baboon might not be able to fight off a leopard, a troop of baboons often is able to do so. In addition, with more individuals cooperating together, some can serve as sentries looking for danger while the other group members are eating or sleeping. Prairie dogs and large flocks of crows normally have some individuals acting as sentries, which makes it nearly impossible to sneak up on a prairie dog town or a flock of crows.
Many prey species, such as schools of fish and flocks of shorebirds, travel in groups in which their movements are highly coordinated. The entire group moves quickly, darting one way and then another as an entire group, as if they were all somehow physically connected with one another. It is believed this behavior creates confusion for the predator. Predators generally need to pick out a single individual in a group that they will focus on and try to capture. A rapidly moving and turning school of fish, flock of birds, or herd of antelope is believed to make it very difficult for the predator to remain focused on a single individual. However, if one individual is unable to keep up with the group, the predator will then be able to focus on it and usually will succeed in catching it.
Some animals form social groups to make travel easier. Canada geese and other bird species typically fly in a V formation. Just like bicyclists who ride behind one another in order to reduce wind resistance, the geese fly in formation to reduce the wind they must encounter. In this situation, the lead bird has the most tiring job, which is why several birds usually take turns leading the V. Some animals congregate in close proximity to one another in cold weather in an effort to stay warm. Small birds are sometimes known to huddle so closely they form a single large ball of birds.
Sometimes social behavior is exhibited by groups of males or females during the breeding season. In some cases, males may band together and try to chase the dominant male away so they have a better chance of mating success. In other instances, males are known to cooperate in making their courtship displays. Turkeys often perform their courtship display in pairs, even though only one of the turkeys ends up doing most of the mating. Why would the unsuccessful male agree to help? The two male turkeys are usually brothers. Since brothers share about 50 percent of the same genes, even if only one brother mates, many of the genes of the unsuccessful brother are passed on too.
In some species, the females form social groups during the breeding season. In certain circumstances, females will look after one another's offspring while the other mother goes out to find food. In other species, such as lemurs, females may form social groups as a kind of defense. Males of some lemur species will try to kill the offspring of females that mated with another male. By banding together, the females are sometimes able to ward off the attacking male.
The male bower bird, of the Australian rainforest, has long interested scientists with its unusual courting behavior. The bower constructs a sort of bachelor pad on the forest floor, a complex structure of twigs, leaves, and moss. Further decorating it with berries and shells and feathers, scientists believe that it is specifically designed to attract mates.
Many animals form social groups only during certain times of the year. Many bird species flock together in foraging groups in the winter. However, these same birds that sought one another out in the winter set up breeding territories in the spring and will go to great lengths to keep the same birds out of their territory. Thus, for many species, social behavior is a flexible form of animal behavior, one that can be adopted or abandoned depending on the conditions of the environment and the time of year.
Some of the most well-developed social behavior is exhibited by insects such as ants, termites, bees, and wasps. Many of these species live in colonies with thousands or even millions of individuals. One benefit of social behavior for these insects is that different individuals specialize in certain activities. For example, some are the workers who build the colony and go out looking for food that they bring back. Other individuals are the soldiers of the colony. Their job is to continually patrol the colony perimeter and to protect the colony from possible attacks from other colonies. In many ant and bee colonies, all worker and soldier ants are females. Males are usually present in the colony, but do not contribute much. Finally, there is the queen ant or bee. The queen's only job for her entire life is to lay eggs that the workers will care for.
There are substantial benefits to forming social groups and there are also some definite costs to living closely with others of the same species. First, one competes most with others that are most like oneself, and thus a member of a social group always has to share or compete with others for resources. Second, because of the numbers and close proximity of individuals in many social groups, disease may spread through social groups relatively rapidly.
see also Behavior, Genetic Basis of; Behavior Patterns; Field Studies in Animal Behavior; Mating Systems; Natural Selection; Sociobiology; Symbiosis; Wildlife Biologist
Mark A. Davis
Alcock, John. Animal Behavior, 3rd ed. Sunderland, MA: Sinauer Associates, 2001.
Wilson, E. O. Sociobiology, abridged ed. Cambridge, MA: Belknap Press of Harvard University Press, 1980.