Exploring seasonal variation in the faecal glucocorticoid concentrations of African elephants (Loxodonta africana) living in a drought-prone, anthropogenic landscape
Georgia Troup
A * , Robert Heinsohn A , Lucy E. King B C and Katie L. Edwards D E
+ Author Affiliations
- Author Affiliations
A Fenner School of Environment and Society, The Australian National University, Canberra, ACT, Australia.
B Save the Elephants, PO Box 54667, Nairobi, Kenya.
C Department of Zoology, University of Oxford, Oxford, UK.
D Center for Species Survival, Smithsonian Conservation Biology Institute, Front Royal, VA, USA.
E North of England Zoological Society, Chester Zoo, Upton-by-Chester, UK.
Wildlife Research 49(5) 415-427 https://doi.org/10.1071/WR21003
Submitted: 6 January 2021 Accepted: 24 October 2021 Published: 25 March 2022
© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing.
Abstract
Context: The wide-ranging movement of African elephants (Loxodonta africana) is largely driven by the spatio-temporal distribution of water and forage, and often leads to their travelling outside of formally protected areas. With an increase in drier periods predicted across Africa due to climate change, it is critically important to understand how elephants physiologically respond to alterations in the availability and distribution of resources.
Aims: We assessed variation in the adrenal activity of elephants living in Kenya’s Tsavo East National Park between wet and dry seasons, as well as among individuals found in Tsavo East National Park and privately protected Rukinga Wildlife Sanctuary (part of the Kasigau REDD+ wildlife corridor) in the dry season, when the area experiences an influx of elephants in search of alternative resources.
Methods: We opportunistically collected fresh elephant faecal samples across the two seasons and locations for analysis of faecal glucocorticoid metabolite (fGCM, a proxy for stress) and nitrogen (Nf, an indirect measure of diet quality) concentrations. The Normalised Difference Vegetation Index (NDVI) was employed as an additional indicator of habitat quality.
Key results: In Tsavo East N.P. Nf and NDVI were both significantly lower during the dry season, indicating poorer habitat quality compared with the wet season. Although elephant fGCM concentrations tended to be higher in the dry season than the wet, the differences were not significant. There was no difference between elephant fGCMs measured in Tsavo East N.P. and Rukinga W.S. during the dry season, nor in habitat quality between the two locations.
Conclusions: Elephants living in Tsavo may be physiologically unaffected by (or adapt to) typical seasonal changes in habitat quality that could lead to nutritional stress; however, whether this is the case during extended periods of severe drought requires further investigation. Rukinga W.S. provides a safe haven of sufficient habitat quality for elephants searching for alternative resources during this period.
Implications: Extended dry periods are likely to become increasingly common in semiarid savannahs, and implications for wildlife must be closely monitored. Privately protected land outside formally protected areas plays an important role in conservation efforts, which should be considered when making land management plans.
Keywords: African elephants, anthropogenic, conservation, endocrine analysis, forage quality, glucocorticoids, habitat, herbivore nutrition, seasonal, stress.
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