Although territorial defense is a common form of reproductive competition among male vertebrates, the exact reproductive consequences of this behavior are often poorly understood. To explore relationships between territoriality and reproductive success in a nongroup-living mammal, we quantified patterns of space use, mating success, and fertilization success for males in a free-living population of arctic ground squirrels (Spermophilus parryii plesius). Because litters of this species are sired almost exclusively by a female's first mate, we predicted that territory ownership would be associated with first access to estrous females. During the 2-week period when mating occurred, each male in the study population attempted to defend [...]
