Abstract
Movement strategies of animals have been well studied as a function of ecological drivers (e.g., forage selection and avoiding predation) rather than physiological requirements (e.g., thermoregulation). Thermal stress is a major concern for large mammals, especially for savanna elephants (Loxodonta africana), which have amongst the greatest challenge for heat dissipation in hot and arid environments. Therefore, elephants must make decisions about where and how fast to move to reduce thermal We tracked 14 herds of elephant in Kruger National Park (KNP), South Africa, for 2 years, using GPS collars with inbuilt temperature sensors to examine the influence of temperature on movement strategies, particularly when accessing water. We first confirmed that collar-mounted temperature loggers captured hourly variation in relative ambient temperatures across the landscape, and, thus, could be used to predict elephant movement strategies at fine spatio-temporal scales. We found that elephants moved slower in more densely wooded areas, but, unexpectedly, moved faster at higher temperatures, especially in the wet season compared to the dry season. Notably, this speed of movement was highest when elephants were approaching and leaving water sources. Visits to water showed a periodic shuttling pattern, with a peak return rate of 10-30 h, wherein elephants were closest to water during the hotter times of the day, and spent longer at water sources in the dry season compared to the wet season. When elephants left water, they showed low fidelity to the same water source, and traveled farther in the dry season than in the wet season. In KNP, where water is easily accessible, and the risk of poaching is low, we found that elephants use short, high-speed bursts of movement to get to water at hotter times of day. This strategy not only provides the benefit of predation risk avoidance, but also allows them to use water to thermoregulate. We demonstrate that ambient temperature is an important predictor of movement and water use across the landscape, with elephants responding facultatively to a landscape of thermal stress.
Highlights
Ranging behavior of mammals is influenced by an optimization of multiple ecological drivers, from maximizing resource acquisition and habitat selection (Fortin et al, 2003; BastilleRousseau et al, 2018), to minimizing predation risk and competition (Valeix et al, 2009; Thaker et al, 2011; Vanak et al, 2013)
We show that temperature and water-dependency are strong drivers of the movement of wild free-ranging savanna elephants across large spatio-temporal scales
In Kruger National Park (KNP), we find that elephants moved faster at higher temperatures
Summary
Ranging behavior of mammals is influenced by an optimization of multiple ecological drivers, from maximizing resource acquisition and habitat selection (Fortin et al, 2003; BastilleRousseau et al, 2018), to minimizing predation risk and competition (Valeix et al, 2009; Thaker et al, 2011; Vanak et al, 2013). We have a strong understanding of movement strategies based on the ecology of animals, but the importance of animal physiology in driving movements is becoming increasingly apparent. The energetics of movement strongly influence how terrestrial carnivores use terrain and other habitat features during hunting (Scantlebury et al, 2014; Williams et al, 2014; Bryce et al, 2017). With advances in animal telemetry allowing for the incorporation of a range of sensors (Kays et al, 2015), and the rapidly developing field of movement ecology (Nathan et al, 2008), we have an opportunity to understand movement strategies as an outcome of balancing ecological drivers, but as a function of physiological requirements and constraints
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
