The effect of climatic variables on the demography and behaviours of banded mongooses (Mungos mungo)

Human-induced climate change negatively affects animal reproduction and survival. Understanding vulnerability to climate change requires knowledge on how animals respond to changes in environmental conditions. Here, I used a long-term (>20 years) dataset of climatic, life-history and behavioural data on a wild population of banded mongooses to investigate how environmental change will affect this cooperatively breeding equatorial mammal. Using time series decomposition, I show how reproduction and early-life survival is affected by rainfall and temperature at varying timescales (seasonal, long-term trends, and short-term variation). Births occur year-round, but reproduction is usually timed so that females either conceive or give birth during the wet seasons where food is most plentiful (Chapter 2). Next, I used structural equation modelling to investigate both direct effects of environmental conditions on early-life survival and indirect impacts via changes to cooperative behaviour (Chapter 3). High levels of rainfall boosted helping effort, which in turn increased pup survival, but high temperatures had both direct and indirect negative effects on survival. I found no evidence for a buffering effect of cooperative social groups on harsh environmental conditions, which has been previously suggested for other species. Chapter 4 presents support for high temperatures limiting offspring growth via the heat dissipation limit hypothesis, which predicts that high temperatures limit metabolic expensive processes such as lactation, due to inability to disseminate the additional heat produced. Finally, banded mongooses behaviourally thermoregulate by resting more and foraging less under high temperatures (Chapter 5). However, this is insufficient to mitigate increases in body surface temperatures. Overall, my results suggest that banded mongooses should suffer from rising temperatures with limited or no relief via behavioural adjustments or social buffering. However, predicted increases in rainfall may partially mitigate these impacts, highlighting the challenging complexity in predicting overall effects of climate change on wild animal populations.