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Very little is known about the drill Mandrillus leucophaeus, a primate species. This dissertation details research on life-history and behavioral characteristics for a growing semi-wild population housed in forested enclosures at the Drill Rehabilitation and Breeding Center (DRBC) in Nigeria. Causes of mortality and survival curves for DRBC drills are described, and compared to other captive Mandrillus populations. Reproductive parameters—age at first swell, age at first birth, adolescent infertility interval, gestation length, and interbirth intervals—are described for a large sample size of females. Reproductive variability based on maternal condition and seasonal factors is explored. The behavioral repertoire and frequency of social interactions is compared for large social groups of drills in an urban versus a forest setting. While qualitatively similar between settings, frequencies of some behaviors differed significantly. Drills in the urban setting interacted with one another more frequently, displaying significantly more affiliative and aggressive contact interactions. Drills in the forest setting interacted less frequently and had a greater repertoire of foraging behaviors. Partner preference analyses showed a tendency for individuals to interact with like age and gender classes. Females prefer grooming related females, although females with fewer relatives had the same number of grooming partners. Some females had grooming bonds with select males. Males displayed affiliative interactions mainly toward females, and frequently aggressed or avoided other males. Juveniles were most likely to associate with other juveniles in large, boisterous play groups. Wounding analyses showed that the most likely cause of wounding was social altercation. Males and females received an equal number of wounds. Males were more likely to be the initiators of wounds, to be wounded by another male, and to receive serious wounds. Females were equally likely to be wounded by either sex. While males most often received wounds to the face and hands, females were more likely to sustain wounds to the ano-genital or back leg area. Finally, woundings for both males and females occurred most frequently around the age at maturation, with males most likely to be wounded during the dry season, the main period of female estrus.
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