Behavioural thermoregulation in free-ranging savanna elephants (Loxodonta africana)

Abstract

Savanna elephants currently inhabit some of the hottest environments in Africa. Because of climate change, these environments are likely to get hotter. Due to their large body size and small body surface area to volume ratio, elephants may face difficulties in dissipating heat. Despite this suggestion, we do not understand how elephants in their natural environment respond to present day climatic extremes, which limits our ability to predict how elephants may respond to climate change. The goal of my study was to quantify behavioural responses of elephants to environmental temperature and to investigate the thermal benefits thereof. In so doing, I aimed to assess the potential consequences of environmental temperature on habitat selection and individual fitness, as well as their ability to adapt to climate change. I used continuous behavioural observations and ambulatory temperature recording devices to quantify and assess daytime behavioural responses to environmental temperature in seven tame, free-ranging savanna elephants in Botswana’s Okavango Delta. The elephants were unrestrained and free to roam in their natural environment. I found that environmental temperature played a significant role in dictating elephant behaviour within a day. At about 30°C, elephants adjusted their behaviour aimed at reducing environmental heat loads and increasing heat dissipation (e.g. shade use, wetting behaviour). I further found that resting increased and feeding decreased with environmental temperature. Age was not a significant factor dictating elephant behaviour. However, the presence of a suckling calf influenced family group behaviour by increasing the probability of shade use and decreasing the probability of walking. The clear flexible ability of elephants to respond behaviourally to present day environmental temperatures is a promising observation in the face of climate change. However, I suggest that environmental temperature is likely a key determinant of habitat selection and space use in elephants that may have potential consequences for calf survival, sexual segregation and individual fitness. Further investigation of these consequences is warranted.