Territoriality

Territoriality is the behavior by which an animal lays claim to and defends an area against others of its species , and occasionally members of other species as well. The territory defended could be hundreds of square miles in size, or only slightly larger than the animal itself. It may be occupied by a single animal, a pair, family, or entire herd or swarm of animals. Some animals hold and defend a territory year-round, and use the territory as a source of food and shelter. Other animals establish a territory only at certain times of the year, when it is needed for attracting a mate, breeding, and/or raising a family.

The advantages of territoriality

Many different species exhibit territorial behavior, because it offers several advantages to the territorial animal. An animal which has a "home ground" can develop reflexes based on its surroundings. Thus it can react quickly to dangerous situations without having to actively seek hiding places or defensible ground. By spacing out potential competitors, territoriality also prevents the depletion of an area's natural resources. This regulation of population density may also slow down the spread of disease . In addition, territorial behavior exposes weaker animals (which are unable to defend their territory) to predation, thereby promoting a healthy population.

Types of territories

Some animals will establish a territory solely for the purpose of having a place to rest. Such a territory is known as a roost, and may be established in a different area every night. Roosts are often occupied and defended by large groups of animals, for the protection offered in numbers. Individual personal spaces within the roost may be fought over as well. Roosting spots nearer the interior of a group of animals are often the safest, and therefore the most highly prized.

Several species of birds and a few mammals are known to establish specialized territories during the breeding season, which are used only to attract mates through breeding displays. This type of territory is known as a lek, and the associated behavior is called lekking. Leks are among the most strongly defended of all territories, since holding a good lek increases the chances of attracting a mate. Leks are generally of little use for feeding or for bringing up young, and the animals will abandon its lek once it attracts a mate or mates, or if it becomes too weak to defend it.

Defending a territory

Some animals will defend their territory by fighting with those who try to invade it. Fighting, however, is not often the best option, since it uses up a large amount of energy , and can result in injury or even death. Most animals rely on various threats, either through vocalizations, smells, or visual displays. The songs of birds, the drumming of woodpeckers , and the loud calls of monkeys are all warnings that carry for long distances, advertising to potential intruders that someone else's territory is being approached. Many animals rely on smells to mark their territories, spraying urine, leaving droppings or rubbing scent glands around the territories' borders. Approaching animals will be warned off the territory without ever encountering the territory's defender.

On occasion, these warnings may be ignored, and an intruder may stray into a neighboring territory, or two animals may meet near the border of their adjacent territories. When two individuals of a territorial species meet, they will generally threaten each other with visual displays. These displays often will often exaggerate an ani mal's size by the fluffing up of feathers or fur, or will show off the animals weapons. The animals may go through all the motions of fighting without ever actually touching each other, a behavior known as ritual fighting. The displays are generally performed best near the center of an animal's territory, where it is more likely to attack an intruder, and become more fragmented closer to the edges, where retreating becomes more of an option. This spectrum of performances results in territorial boundaries, where displays of neighbors are about equal in intensity, or where the tendency to attack and the tendency to retreat are balanced.

Actual fighting usually only happens in overcrowded conditions, when resources are scarce. Serious injury can result, and old or sick animals may die, leading to a more balanced population size. Under most natural conditions, territoriality is an effective way of maintaining a healthy population. The study of social behaviors such as territoriality in animals may help us also to understand human society, and to learn how individual behavior affects human populations.

See also Competition.

Resources

books

Parker, Steve, Jane Parker, and Terry Jennings. Territories. New York: Gloucester Press, 1991.

David Fontes

KEY TERMS

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Lek

—An area defended by animals of one sex (usually males) because ownership increases the chance of attracting members of the other sex.

Territory

—An area defended by an animal against others, usually of the same species.