The effects of density, food, and interspecific interference on home range size in Peromyscus leucopus and Peromyscus maniculatus

Abstract

Home ranges of Peromyscus leucopus noveboracensis and Peromyscus maniculatus nubiterrae were compared between species, sexes, and ages at high and low densities on (i) control grids with two species present, (ii) grids supplied with additional food, and (iii) grids from which one of the species was removed. In addition, aggressive behavior of mice from high and low densities was compared. Home ranges averaged 590 m2 and did not differ between species or ages, but males had slightly larger home ranges than females. Sizes of home ranges on food-supplemented grids did not differ significantly from control grids. Thus, food does not appear to be the major factor determining minimum size of home range in these Peromyscus species. Home ranges on removal grids did not differ significantly from home ranges on control grids. Interspecific aggression for space was indistinguishable from intraspecific aggression. Sizes of home ranges were marginally negatively associated with population density. At low densities, individuals of the same sex maintained exclusive home ranges by mutual avoidance. At high densities, home ranges became somewhat constricted, but reached a minimum size of about 500 m2. At this point, home ranges did not become smaller; instead the overlap increased and increased levels of aggression and territorial defense resulted. Aggression and territorial defense were density dependent and occurred only when populations exceeded 25 to 30 mice/ha.