The Kangaroo rat is a good example. This is a very general topic. Read about these complex behaviors in this short review in your text on page 336. It is an area defended from other members of the same species so there will be a secure food supply and shelter for the owners of the territory. Many mammals mark their territories, especially those of the Deer Family, the Dog Family and the Cat Family.
Some mammals defend a territory for mating purposes.
Read about California Sea Lions. Birds defend territories just as frequently as mammals. Reproduction and Development Viviparity is well developed in mammals. They also nurse young, another demand on energy. Therefore there is usually a period when females and males are not sexually active.