Our original intention was to carry out a giving-up density experiment with three troops of Vervet monkeys Cercopithecus aethiops at the Wits Rural Research Facility in eastern South Africa. We placed 7 lidded buckets containing peanuts and wood blocks at different heights within, and distances away from, three marula treesSclerocyra birrea where separate troops foraged. The presence of the wood blocks mimicked the time and effort spent while naturally foraging, and the hole in the lid (6 cm) was smaller than the sizes of the wooden pieces (7 cm diameter). The amount of peanuts eaten from each bucket after a foraging period indicates that these were the more favorable feeding patches - where they felt the safest (lowest predation risk), and spent the most time foraging. We realized that the amount of natural, more easily accessible food sources to the monkeys was large because it was summer in South Africa. They had no interest in our buckets of peanuts while there was ample fresh food nearby. As a result, we switched tactics to observation-based data collection. We found the most visible troop and spent multiple days taking ethogram observations of as many individuals as possible. Every 15 seconds, the behavior of every individual in the sample was recorded. Behaviors such as vigilance, foraging, and interacting with peers and offspring were common. These ethogram samples suggest the comfort level of the troop in their environment, their apparent stress towards food source availability, and their perception of nearby predation risk.
Dr. David Ward
We set up a giving-up density experiment with Vervet monkeys at the Wits Rural Facility in South Africa. We placed 7 lidded buckets containing peanuts and wood blocks at different heights within, and distances away from, three marula trees. The blocks served as obstacles, mimicking the time and effort spent in natural foraging. The amount of peanuts eaten from each bucket after a foraging period indicates more favorable feeding patches. We realized the peanuts were not favorable due to high summer food availability. Instead, we observed the monkeys, recording behaviors such as vigilance, foraging, and interacting with peers and offspring. These ethogram samples suggest the troop’s comfort level in their environment, their apparent stress towards food availability, and their perception of nearby predation risk.