Territoriality as a regulating factor is:
Territoriality is biotic because it arises from interactions among organisms, and it is density-dependent because encounters and exclusion become more frequent as abundance rises. Once available territories are occupied, newcomers may be prevented from breeding or forced into poor habitat. This lowers recruitment or raises dispersal and mortality, creating negative feedback on population growth. Population regulation concerns feedback, not mere limitation. A drought may sharply reduce numbers yet fail to push the population toward a repeatable equilibrium. Competition, disease, territoriality,
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 5