My name is Rachel Sassoon and I am currently doing an MSc by Research in Biological Anthropology at Durham University. My project is looking at landscapes of fear and giving-up densities in samango monkeys (Cercopithecus albogularis erythrarchus).
Most foraging animals demonstrate spatial variation in their feeding behaviour. This is known as the ‘landscape of fear’. These landscapes of fear express the trade-off between food and safety. A forager may choose not to maximise its energy gain or resource acquisition and may choose a lower rate of gain if such circumstances mean greater safety from predators. The number of resources left behind when a forager leaves a food patch is known as the giving-up density (GUD). Given the choice of two habitats, with similar resource levels, a forager should spend more time in the ‘safer’ habitat and when offered depletable food patches with equal opportunity, foragers should leave the ‘riskier’ areas at a higher GUD. Thus, foragers bias feeding behaviour toward safer habitats and have higher GUDs in riskier patches.
GUDs have been employed in a number of species including rodents, birds and ungulates. However, the use of GUDs in measuring predation risk is fairly new to primate studies. Primates make for an interesting study group as predation risk can be measured vertically, as well as horizontally. In arboreal species, like samango monkeys, one would assume that there will be a landscape of fear, with proximity to trees (horizontal) but also with height, from the ground into trees (vertical).
My objectives are to set up artificial food patches, at increasing heights, to measure samango monkey GUDs and determine if significant differences are related to height. The food patches are plastic tubs, containing 25 peanut halves mixed thoroughly in 4 litres of sawdust. These patches are spaced approximately 20m apart, along a 3×4 grid and hung in trees at heights of 0.1m, 2m and 5m. The experimental array will be set up in two areas of a specific habitat type. The location of the arrays will be based on the landscape of fear generated by a previous study on this population of samango monkeys by PhD student, Ben Coleman, also based at Durham University. Adding behavioural observations will determine what the monkeys are doing at the food patches. Repeating the array in two areas (High Risk Array; Low Risk Array), shown to differ in predation risk, will determine whether there are differences in both the GUDs and behaviour. Do risky areas result in higher GUDs and behaviourally; more co-feeding, individuals in closer proximity to one another and increased vigilance when foraging?
Above: a samango monkey feeding from a plot