Behavior patterns in which an animal actively defends a space or some other resource. One major advantage of territoriality is that it gives the territory holder exclusive access to the defended resource, which is generally associated with feeding, breeding, or shelter from predators or climatic forces. Feeding and breeding territories can be mobile, such as when an animal defends a newly obtained food source or a temporarily receptive mate. Stationary territories often serve multiple functions and include access to food, a place to rear young, and a refuge site from predators and the elements.

Territoriality can be understood in terms of the benefits and costs accrued to territory holders. Benefits include time saved by foraging in a known area, energy acquired through feeding on territorial resources, reduction in time spent on the lookout for predators, or increase in number of mates attracted and offspring raised. Costs usually involve time and energy expended in patrolling and defending the territorial site, and increased risk of being captured by a predator when engaged in territorial defense.

Because territories usually include resources that are in limited supply, active defense is often necessary. Such defense frequently involves a graded series of behaviors called displays that include threatening gestures such as vocalizations, spreading of wings or gill covers, lifting and presentation of claws, head bobbing, tail and body beating, and finally, direct attack. Direct confrontation can usually be avoided by advertising the location of a territory in a way that allows potential intruders to recognize the boundaries and avoid interactions with the defender. Such advertising may involve odors that are spread with metabolic by-products, such as urine or feces in dogs, cats, or beavers, or produced specifically as territory markers, as in ants. Longer-lasting territorial marks can involve visual signals such as scrapes and rubs, as in deer and bear. Chemical ecology Ethology Population ecology