territory is defebded against

1. predator
2. any intruder
3. intruder of another species
4. intruder of same species

Rather than retaining a territory simply by fighting, for some animals this can be a 3-stage process. Many animals create "sign-posts" to advertise their territory. Sometimes these sign-posts are on the boundary thereby demarcating the territory, or, may be scattered throughout the territory. These communicate to other animals that the territory is occupied and may also communicate additional information such as the sex, reproductive status or dominance status of the territory-holder. Sign-posts may communicate information by olfactory, auditory, or visual means, or a combination of these. If an intruder progresses further into the territory beyond the sign-posts and encounters the territory-holder, both animals may begin "ritualised aggression" toward each other. This is a series of stylised postures, vocalisations, displays, etc. which function to solve the territory dispute without actual fighting as this could injure either or both animals. Ritualised aggression often ends by one of the animals fleeing (generally the intruder). If this does not happen, the territory may be defended by actual fighting, although this is generally a last resort.