Behavioural responses of vervet monkey Chlorocebus pygerythrus infants in a novel fostering programme

Van Niekerk, Chame'
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Vervet monkeys Chlorocebus pygerythrus are viewed as pests by farmers and home owners. Consequent attempts to exterminate problem vervet monkey individuals often results in orphaned young whose mothers are killed. I studied the rehabilitation of orphans at The Vervet Monkey Foundation, South Africa. My aim was to assess the success of the fostering program at the Foundation. Orphaned vervet monkeys are fostered by adult vervet monkey females at the Foundation using a specific protocol focused on reducing human rearing. The protocol involves a step-wise process of integration, comprising of a quarantine phase to the next phase of Disneyland to develop independent bottle feeding, an integration phase to assist in the adoption by a foster female and finally release into the troop of the foster mother. I evaluated the success of fostering of eight orphans into two troops, and compared this protocol to published literature. I also evaluated the behaviours of the orphans and their interactions with their foster mother to assess the process of fostering at a finer scale. Following release into the troops, I also investigated the responses of the fostered offspring to vervet alarm calls to provide another measure of the integration of orphans into the troops. Calls were played alone or accompanied with a dummy predator model stimulus, and I assessed whether the orphans sought the protection of foster mother or another troop member. During the fostering process, 89% of the orphans were successfully fostered to their designated troops. A similar high success rate was reported in other primate studies. These studies suggested that the protocol followed for rearing had more impact on success and behaviour than the period of human-caregiving. Orphans altered some of their behaviours during alarm call playbacks, particularly when accompanied with the visual aid. However, they ran for the cover of the trees rather than sought out the foster mother or another individual. My study demonstrated a high fostering success of orphaned vervet monkeys with little or no socio-negative and abnormal behaviour and close association with the foster mother. The alarm call playback experiments showed that the orphans did recognise conspecific alarm signals but did not rely on the foster mother for protection, possibly related to their growing independence of the foster mother.
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2019