The study on territoriality in animals shows that there is more theory than actual data on the subject. Future research should focus on testing these theories in the field. Key areas for study include how an animal's energy level and breeding state affect territorial decisions, the impact of habitat shape and neighbors on defense costs, and how environmental changes influence territorial behavior. The study of territoriality is at a challenging stage, requiring careful selection of study systems and thorough testing of hypotheses to advance our understanding.