While nations use flags to claim their lands, cats unfortunately tend to spray urine or leave feces instead. Such actions can quickly leave them looking for new territory in the least-tolerant of pet-owning homes.

Cats also mark territory by scratching and rubbing their cheeks against objects. Deal with territory-crazy cats by minimizing the need to spray and by channeling their marking behavior toward more acceptable actions and targets.

Encourage acceptable marking by providing plenty of tall scratching posts and cat trees and by praising cheek rubbing. Feliway, a pheromone-based product, may help to calm the competitive stress that leads to marking. When the competition is the neighbor's cat outside, close the blinds or keep cats out of rooms that allow them to see their rivals.

Animal behavior experts Susan and Roland Tripp are the authors of "On Good Behavior." For more information, visit their Web site at AnimalBehavior.net.