Cat Territorial Instincts
The domestic cat has no need of hunting or protecting their territory from competitors to be able to survive, but it still has the instinct to do so. All cats make their territories based around their home. The size of their territories may vary according to the amount of cats in the area and the space that there is available. Cats that are not castrated have much larger territories than males that are and females. If a male enters into the territory of another male cat it may create a fight, but cats are more civilized, they try to avoid fights by following a known trail.
One of the most important ways of communication between cats is by scent. Cats mark their territory with their scent, it is also used to attract the opposite sex. The most common way of marking territory, specially for a male, is by leaving traces of urine. Even though cats bend to urinate they let out their scent when they are urinating standing up. To do this it leans on a vertical object and lets out short sprays of urine which fall backwards, it lifts its tail and trembles a bit, all the while arching its back.
Other ways of leaving scent is by rubbing itself on objects with its head and body to leave off scents produced by the sweat glands of the skin. They also scratch on poles and-trunks to leave off smells released by the pads on their claws.