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Sexual Interference Behaviors in Male Adult and Subadult Tibetan Macaques (Macaca thibetana)
Kui-Hai Pang1, Amanda K Rowe2, Lori K Sheeran3
1School of Resource and Environmental Engineering, Anhui University, Hefei 230601, China.
Abstract:
Male nonhuman primate sexual interference, which includes copulation interruption and copulation harassment, has been related to reproductive success, but its significance has been challenging to test. Copulation interruption results in the termination of a copulation before ejaculation, whereas copulation harassment does not. We conducted this study using the all-occurrence behavior sampling method on sexual interference behaviors of seven adult and four subadult male Tibetan macaques (Macaca thibetana) in mating and non-mating seasons at Mt. Huangshan, China, from August 2016 to May 2017. Our results showed that males' individual proportion of copulation interruption and harassment was higher during the mating season than during the non-mating season. In addition, dominant males more often performed interruption, whereas subordinate males more often performed harassment. We found no difference in the individual proportion of copulation interruption or harassment between adult and subadult males. Adult and subadult males both directed copulation interruption and harassment more often toward the mating male than toward the mating female. Lastly, the post-ejaculation phase of copulation was shorter when copulation harassment occurred than when it did not. Our results suggest that sexual interference may be an important mating tactic that adult and subadult males use in male-male sexual competition.
Insights
Male Tibetan macaques use sexual interference, like interrupting or harassing copulations, more during mating seasons. Dominant males interrupt, while subordinates harass, suggesting these are key male-male competition tactics.
Area of Science:
- Primate behavior
- Sexual selection
- Animal communication
Background:
- Sexual interference, including copulation interruption and harassment, is observed in male nonhuman primates.
- Its direct impact on reproductive success and its role in male-male competition remain under-investigated.
Purpose of the Study:
- To investigate the occurrence and patterns of sexual interference behaviors in Tibetan macaques.
- To determine the influence of mating season, social dominance, and age on these behaviors.
- To assess the impact of sexual interference on copulation duration.
Main Methods:
- All-occurrence behavior sampling was used to record sexual interference in male Tibetan macaques.
- Data were collected from adult and subadult males over mating and non-mating seasons.
- Behaviors were analyzed in relation to social dominance, age class, and mating status.
Main Results:
- Sexual interference (interruption and harassment) was more frequent during the mating season.
- Dominant males predominantly performed copulation interruption, while subordinate males engaged more in harassment.
- No significant age-related differences in interference behavior were found between adult and subadult males.
- Interference was directed more towards the mating male than the mating female.
- Copulation harassment shortened the post-ejaculation phase.
Conclusions:
- Sexual interference is a significant mating tactic employed by male Tibetan macaques in male-male competition.
- The specific tactics (interruption vs. harassment) are associated with social dominance.
- These behaviors are context-dependent, increasing during the mating season.
