A pattern of animal behavior, territoriality implies a fixed area (or territory) from which intruders are excluded by the owner through a combination of advertising, threatening, and attacking behaviors. It is important to distinguish between a territory and a home range, because the appearance of an outsider will elicit different reactions from the animal that lives in, or frequents, the area. Unlike an animal's marked territory, its home range is an area in which the individual roams about but the individual rarely defends it against other animals. There are some species, such as the breeding song sparrow, whose territory and home range are one and the same. In the majority of species, however, the territory tends to be smaller than the home range or the two areas overlap so that only part of the home range is defended as territory.

These elk rutting bulls fight in a field...