Abnormal behaviour in captive sooty mangabeys

The influence of several factors on abnormal behaviour was investigated in 46 singly housed sooty mangabeys (Cercocebus atys) (eight nursery-reared, 38 mother-reared), including self-injurious, self-directed, stereotypic locomotion, and faeces/urine-related behaviours (SIB, SDB, SL, FUR, respectively). An analysis of behavioural assessments spanning a mean of four years per subject showed that 83% displayed at least one form of AB during that time, with SL being the most common (mean of 3.06% of observation sessions and displayed by 59% of subjects) and SIB the least common (mean of 0.09% of all observation sessions and displayed by 20% of subjects). Like other primate species, displaying AB was influenced by the percent of life spent singly housed and by nursery-rearing during infancy. However, unlike some other primates, there was no influence of the number of yearly sedations or room relocations on AB; also, females were more likely to display AB than male mangabeys. To investigate the effects of nursery-rearing further, we compared the eight nursery-reared, singly housed subjects with eight nursery-reared subjects that were socially housed since the age of three years. While nursery-reared subjects in single housing displayed SL and FUR in higher proportions than those in social housing, subjects from both environments displayed SIB and SDB in equal proportions, suggesting that they are persistent forms of AB for nursery-reared mangabeys even after long-term social housing. To reduce future incidence of AB in captive mangabeys, we recommend minimising nursery-rearing and the duration of single-housing whenever feasible or avoiding them altogether.