Original Research ARTICLE
Fine-scale tracking of ambient temperature and movement reveals shuttling behaviour of elephants to water
- 1Centre for Ecological Sciences, Division of Biological Sciences, Indian Institute of Science (IISc), India
- 2Groningen Institute for Evolutionary Life Sciences, University of Groningen, Netherlands
- 3Department of Coastal Systems, Royal Netherlands Institute for Sea Research, Netherlands
- 4Ashoka Trust for Research in Ecology and the Environment (ATREE), India
- 5Resource Ecology Group, Wageningen University & Research, Netherlands
- 6School of Life Sciences, University of Kwazulu-Natal, South Africa
- 7Department of Genetics, Evolution and Environment, University College London, United Kingdom
- 8Wellcome Trust DBT India Alliance, India
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 stress. 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 hours, 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 travelled 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”.
Keywords: Savanna elephant Loxodonta africana, thermoregulation, GPS telemetry, Water, Waterholes, Kruger National Park, movement ecology, speed, Shuttle
Received: 14 Aug 2018;
Accepted: 08 Jan 2019.
Edited by:Thomas Wassmer, Siena Heights University, United States
Reviewed by:Blandine F. DOLIGEZ, Centre National de la Recherche Scientifique (CNRS), France
Andrea Fuller, University of the Witwatersrand, South Africa
Copyright: © 2019 Thaker, Gupte, Prins, Slotow and Vanak. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dr. Maria Thaker, Centre for Ecological Sciences, Division of Biological Sciences, Indian Institute of Science (IISc), Bengaluru, Karnataka, India, firstname.lastname@example.org