Use of Introduction Enclosures to Integrate Multimale Cohorts into Groups of Female Rhesus Macaques (Macaca mulatta)

Abstract

Integrating animals into a new group is a challenge for both free-ranging and captive adult male rhesus monkeys (Macacamulatta), and for females in groups receiving new males. To ensure the genetic viability of the population, however, maletransfers must occur in both natural and captive settings. To facilitate the introduction of groups of adult males to adult females, we designed a new enclosure that is attached to the outdoor compound where females are housed. Here we describethe construction of 3 introduction enclosures, their use during 4 introductions of groups of adult males to adult females, abrief comparison of introduction success rates associated with the new introduction enclosures with those of our traditionalmale introduction method, and a critique by the various groups of staff members working with the new enclosures. Overall, the introduction enclosures benefitted both the macaques and the facility personnel and appear to be a useful enhancementto our process of integrating breeding groups.

Factors influencing the success of male introductions into groups of female rhesus macaques: Introduction technique, male characteristics and female behavior

“…Introduction of novel adult males into female groups is a common practice for captive breeding colonies of rhesus macaques which mimics the natural pattern of male migration in wild populations. Rhesus macaques are often aggressive toward newcomers (Bernstein & Mason, 1963), and introducing unfamiliar adult males to a group of females is risky and often unsuccessful (Bailey, Young, et al, 2021; Rox et al, 2019). To reduce the risk of injury and improve the likelihood of males' successful integration, we developed a new introduction method: an introduction enclosure attached to the females' outdoor compound that allows multimale groups to live continuously next to the females.…”

“…Under the “continual exposure” approach, the males were moved from run housing to an introduction enclosure connected to the outdoor portion of the females' compound and remained there, as the introduction enclosures were equipped for permanent housing (e.g., wind‐break panels and heaters (Bailey, Young, et al, 2021)). Males had continual visual access to the females and protected contact through chain‐link fencing.…”

“…In captivity, male transfer is mediated by colony managers, as macaques do not avoid consanguineous inbreeding with patrilineal kin (although they do avoid breeding with matrilineal kin) (Smith, 1995). A common strategy is to introduce novel adult males (removing resident males before their introduction) to groups of females every few years to prevent males from mating with their daughters (Bailey, Young, et al, 2021; Rox et al, 2021). A potential added benefit of introducing novel adult males is improved social stability of the group because adult males are important policers of within‐group conflict (Beisner et al, 2012, 2016; McCowan et al, 2011), and adult males that are unrelated to the females are more effective policers than natal males (Beisner et al, 2012; Jackson et al, 2012).…”

Effects of medroxyprogesterone acetate on social behavior in female rhesus macaques (Macaca mulatta) depend on male breeding season introductions

“…Study subjects were uniquely dyemarked and tattooed for identification by observers. At the YNPRC, breeder male introductions occur every few years to prevent inbreeding between young females and their fathers as the females mature 29 . Male introductions are conducted during the breeding season when females are more receptive to the presence of the unfamiliar males 22 .…”

“…The study was conducted between March 2017 and January 2020 At the YNPRC, breeder male introductions occur every few years to prevent inbreeding between young females and their fathers as the females mature. 29 Male introductions are conducted during the breeding season when females are more receptive to the presence of the unfamiliar males. 22 Each of our study groups were scheduled to undergo a male introduction during the breeding season we observed.…”