The ecological costs to females in a system with allied sexual coercion

Sexual coercion results from extreme conflict over mating. As a male strategy to overcome female resistance, coercion can impose fitness costs on females. Among mammals, most cases involve single males or temporary coalitions, with allied aggression towards females being rare. Among Shark Bay bottlenose dolphins, Tursiops cf. aduncus, male alliances harass, guard and consort with females to obtain mating access, which has known physical costs to females. However, the behavioural and ecological costs of sexual coercion to females remain largely unexplored. Given the importance of individual differences in ranging and habitat use for dolphin foraging ecology, social networks and fitness, we hypothesized that male coercion also imposes ecological costs on females. Using 25 years of longitudinal data, we examined how adult male presence relates to female space use, and we found that females (N = 32) altered their ranging when associating with adult males but also when they were cycling. Additionally, females reduced the use of their primary (preferred) habitat when with males, but cycling had no effect. Ranging shifts were slightly greater for males than for females when they were together, but only for females did this alter their spatial ecology. While it is also possible that males follow fertile females and/or that females move to avoid males, the well-documented coercive mating system suggests that males, as part of their coercive mating tactics, sequester females to areas that females would not otherwise occupy. Our results show that in a coercive mating system, males can alter females' basic behavioural ecology, and suggest that males spatially sequester individual females via allied consortships.