Monkeys are social animals that both compete and cooperate with their group members. Understanding the dynamics in behaviour of monkeys is not only important for scientific behaviour research, but also to manage our breeding and experimental colonies. To improve our knowledge, we work together with a group of behavioural scientists from the University of Utrecht. As part of this collaboration BPRC hosted the Summer School Observing Primate Behaviour.
Male introduction success
In the wild male rhesus macaques are the dominant sex, but as they do not remain with troops permanently female macaques lead the community. To prevent inbreeding in captive colonies it is important that males migrate between groups. However, males are not always accepted in their new group. Mimicking natural migration patterns may increase the number of successful male introductions. To identify factors that affect the social position of the male in his new group, behavioural researchers followed up 64 introductions. Of these, 49 were successful and the male was accepted in the group for at least four weeks, and 38 resulted in long-term stable social position. After comparing the group’s characteristics, it was found that long term stability was best achieved when males were heavier than the females, were at least 3.5 years old when they were first removed from their natal group, and groups had few matrilines without pregnant females. Read more >
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Overweight and underweight with a new weight‐for‐height index in captive group‐housed macaques
Housing primates in naturalistic groups provides social benefits relative to solitary housing. However, food intake may vary across individual animals within the group, resulting in overweight and underweight animals. Information on relative adiposity (the amount of fat tissue relative to body weight) is needed to monitor overweight and underweight of group‐housed individuals. However, the upper and lower relative adiposity boundaries are currently only known for macaques living solitarily in small cages.
To determine the best measure of relative adiposity and the boundaries of overweight and underweight in group‐housed macaques, the weight‐for‐height indices (WHI) were determined during yearly health checks.
For long‐tailed macaques, comparable data on founder and wild animals were also available. Weight‐for‐height indices (WHI) with height to the power of 3.0 (WHI3.0) for rhesus macaques and 2.7 (WHI2.7) for long-tailed macaques were optimally independent of height and were highly correlated with other relative adiposity measures. The boundary for overweight was similar in group-housed and solitary‐housed macaques. A lower boundary for underweight, based on 2% body fat similar to wild primates, gave a better estimate for underweight in group-housed macaques. We propose that for captive group‐housed rhesus macaques relative adiposity should range between 42 and 67 (WHI3.0) and for long‐tailed macaques between 39 and 62 (WHI2.7). The majority of group‐housed macaques has a normal relative adiposity, a considerable proportion (17–23%) is overweight, and a few (0–3%) are underweight. Read more >
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