Mammalian herbivore resting behaviour under varying degrees of predation risk

Abstract

Rest forms a crucial part of mammalian activity budgets and health. Yet, little research has been done on resting behaviour and the drivers behind resting behaviour. It has been suggested that predation risk, in particular, affects prey activity budgets and behaviour, and could potentially affect prey resting behaviour. Furthermore, factors such as weather, habitat, herd size, and position in the herd may also affect prey behaviour, but the effect of these factors on resting behaviour is still unknown. Thus, the purpose of this study was to explore these factors and how they may affect the resting behaviour of impala (Aepyceros melampus), wildebeest (Connochaetes taurinus), and zebra (Equus burchelli). In my first data chapter, I collected observational data during the day from five study sites in KwaZulu-Natal that varied with regards to predator composition, and thus predation risk. I found that predation risk affected zebra resting probabilities, but not the likelihood of impala or wildebeest resting. Furthermore, I found that herd size, the interaction between predation risk and vegetation cover, position in the herd, and time of day affected the probability of zebra resting. However, only herd size affected impala rest. Surprisingly, none of the factors considered affected the probability of wildebeest resting. I suggest that wildebeest and impala could rest more at night than during the day, and that when rest occurs during the day, it is relatively random. Ultimately, the findings from my first data chapter highlight the species-specific differences in resting behaviour and that predation risk does affect resting behaviour, but not as universally as expected. The results from my first data chapter led me to further investigate wildebeest resting behaviour in my second data chapter. I used GPS data collected from collared wildebeest within Hluhluwe-iMfolozi Park in KwaZulu-Natal, and previously analysed lion habitat use and vegetation data. I found that wildebeest were much more likely to rest at night than during the day. However, when they did rest during the day, both vegetation cover and lion density had negligible effects. By contrast, at night the probability of a wildebeest resting was highest in areas with low lion densities, irrespective of vegetation cover. However, as predation risk increased, the probability of wildebeest resting decreased, specifically in more densely vegetated areas. These findings highlight that wildebeest resting probabilities are affected more by the long- and short-term habitat use by lions, than indirect proxies of predation risk (like vegetation cover). Ultimately, the results from both data chapters imply that predation risk plays a key role in determining prey resting probabilities, but other social, spatial, and temporal factors are also involved.