In a territorial population of pronghorn from Antelope Island, UT, interaction between male dominance and territory defense was examined. High-ranking males were more likely to defend territories. Closely ranked animals engaged in more dominance interactions than distantly ranked individuals, and middle-ranked animals were involved in disproportionately more interactions than either high- or low-ranking animals. Large males possessed large horns and prongs as well as small cheek patches. Results from a factor analysis suggested that large males defended territories with a high density of sage. However, in this study, we did not observe pronghorn feed on sage during the territorial season. Though male pronghorn practiced resource defense polygyny, large, dominant males did not defend territories with a high density of green vegetation or green forbs. Large males appeared to defend territories with low visibility. In 1996, intruders entered areas that contained females throughout the territorial season. During the next year, highly visible, small territories received the most intrusions. Together, these observations suggest defense of tactical locations. Defending a tactical location may help females avoid harassment and males hide the presence of females. Different populations of pronghorn practice different mating systems. To understand this variation, we examined the behavior patterns/rates of individual territorial and bachelor males. The highest rates of activity and behavior patterns occurred in March/April and in September. Territorial males cheek rubbed at a higher rate than bachelors. Territorial males were more active and SPUD (sniff, paw, urinate, and defecate) marked at a higher rate than bachelor males in 1996. After the formation of a bachelor herd in 1997, bachelor males showed higher rates of male-male interactions than territorial males. Territorial males maintained the same activity and behavioral rates in the presence and absence of females. Dispersion pattern of scent marks was more clumped in the presence of females. These findings suggest cheek rubs function more as a space-claiming behavior while SPUD marking is more strongly associated with male-male interactions. Comparison to male behavior in nonterritorial populations indicates that the behavioral mechanisms are present in all populations to accommodate shifts in social systems.