Agonistic behavior in relation to habitat in two species of rodents

The agonistic behavior patterns of adult males of Peromyscus boylii and Dipodomys agilis were studied in the laboratory to determine if the degree of aggression was influenced by the type of habitat. After being moved from an artificial densely vegetated habitat to an artificial sparsely vegetated habitat, three groups of P. boylii displayed increased agonistic behavior. Two of the three groups formed a dominance hierarchy in the sparsely covered environment, whereas the third group displayed only an increase in activity. Dipodomys agilis displayed unexpected conspecific tolerance and formed a dominance hierarchy in two out of three groups while in the sparsely vegetated habitat. The third group included one extremely aggressive individual. Two of his conspecifics were subsequently found dead. All three groups decreased the frequency and intensity of their agonistic behavior when moved from a sparsely covered environment to a densely covered environment, but individual variation and familiarity with the members of the group may be more important than habitat in influencing agonistic patterns. A habitat preference study of both species indicated Peromyscus boylii selected the densely covered environment and Dipodomys agilis selected both types of habitat about equally.