Abstract:
As the effects of global climate change become more apparent,
animal species will become increasingly affected by extreme
climate and its effect on the environment. There is a pressing
need to understand animal physiological and behavioural
responses to climatic stressors. We used the reactive scope
model as a framework to investigate the influence of drought
conditions on vervet monkey (Chlorocebus pygerythrus)
behaviour, physiological stress and survival across 2.5 years
in South Africa. Data were collected on climatic,
environmental and behavioural variables and physiological
stress via faecal glucocorticoid metabolites (fGCMs). There
was a meaningful interaction between water availability and
resource abundance: when food availability was high but
standing water was unavailable, fGCM concentrations were
higher compared to when food was abundant and water was
available. Vervet monkeys adapted their behaviour during a
drought period by spending a greater proportion of time
resting at the expense of feeding, moving and social
behaviour. As food availability decreased, vervet mortality
increased. Peak mortality occurred when food availability was at its lowest and there was no standing water. A
survival analysis revealed that higher fGCM concentrations
were associated with an increased probability of mortality.
Our results suggest that with continued climate change, the
increasing prevalence of drought will negatively affect vervet
abundance and distribution in our population. Our study contributes to knowledge of the limits and scope of behavioural and physiological plasticity among
vervet monkeys in the face of rapid environmental change.
