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Oduor S, Gichuki NN, Brown JL, Parker J, Kimata D, Murray S, Goldenberg SZ, Schutgens M, Wittemyer G. Adrenal and metabolic hormones demonstrate risk-reward trade-offs for African elephants foraging in human-dominated landscapes. CONSERVATION PHYSIOLOGY 2024; 12:coae051. [PMID: 39100509 PMCID: PMC11295215 DOI: 10.1093/conphys/coae051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 06/21/2024] [Accepted: 07/10/2024] [Indexed: 08/06/2024]
Abstract
A key driver of the African savannah elephant population decline is the loss of habitat and associated human-elephant conflict. Elephant physiological responses to these pressures, however, are largely unknown. To address this knowledge gap, we evaluated faecal glucocorticoid metabolite (fGCM) concentrations as an indicator of adrenal activity and faecal thyroid metabolite (fT3) concentrations as an indicator of metabolic activity in relation to land use, livestock density, and human landscape modification, while controlling for the effects of seasonality and primary productivity (measured using the normalized difference vegetation index). Our best-fit model found that fGCM concentrations to be elevated during the dry season, in areas with higher human modification index values, and those with more agropastoral activities and livestock. There was also a negative relationship between primary productivity and fGCM concentrations. We found fT3 concentrations to be higher during the wet season, in agropastoral landscapes, in locations with higher human activity, and in areas with no livestock. This study highlights how elephants balance nutritional rewards and risks in foraging decisions when using human-dominated landscapes, results that can serve to better interpret elephant behaviour at the human-wildlife interface and contribute to more insightful conservation strategies.
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Affiliation(s)
- Sandy Oduor
- Department of Biology, University of Nairobi, PO Box 30197-00100, Nairobi, Kenya
- Department of Reproductive Biology, Smithsonian Conservation Biology Institute, Front Royal, VA 22630, USA
| | - Nathaniel N Gichuki
- Department of Biology, University of Nairobi, PO Box 30197-00100, Nairobi, Kenya
| | - Janine L Brown
- Center for Species Survival, Smithsonian Conservation Biology Institute, Front Royal, VA 22630, USA
| | - Jenna Parker
- Conservation Science and Wildlife Health, San Diego Zoo Wildlife Alliance, San Diego, CA 92027, USA
| | - Dennis Kimata
- Department of Biology, University of Nairobi, PO Box 30197-00100, Nairobi, Kenya
| | - Suzan Murray
- Global Health Program, Smithsonian Conservation Biology Institute, Washington, DC, USA
| | - Shifra Z Goldenberg
- Conservation Science and Wildlife Health, San Diego Zoo Wildlife Alliance, San Diego, CA 92027, USA
| | - Maurice Schutgens
- Conservation Science Department, Space for Giants, PO Box 174-10400, Nanyuki, Kenya
| | - George Wittemyer
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO, USA
- Save the Elephants, P. O. Box, 54667 - 00200, Nairobi, Kenya
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Hariohay KM, Hunninck L, Ranke PS, Fyumagwa RD, Palme R, Røskaft E. Between hunter and climate: the effects of hunting and environmental change on fecal glucocorticoid metabolite levels in two sympatric ungulate species in the Ruaha-Rungwa ecosystem, Tanzania. CONSERVATION PHYSIOLOGY 2023; 11:coad002. [PMID: 38026801 PMCID: PMC10660377 DOI: 10.1093/conphys/coad002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 11/22/2022] [Accepted: 01/31/2023] [Indexed: 12/01/2023]
Abstract
Understanding the drivers of animal population decline is a key focus of conservation biologists. Anthropogenic activities such as hunting have long been established as potentially detrimental to a population's persistence. However, environmental perturbations such as increased temperature variability, exacerbated by climate change, can also have important effects on animal populations. Animals can respond to these challenges by adjusting both their behavior and physiology. We measured fecal glucocorticoid metabolites (FGMs) of common impala (Aepyceros melampus) and greater kudu (Tragelaphus strepsiceros), both currently in stable populations, to examine effects of hunting, forage availability, daily variability in temperature and group size on their physiological stress response. The study was conducted across two adjacent protected areas, (i) one non-hunted area (Ruaha National Park; RNP) and (ii) one area used for trophy hunting (Rungwa Game Reserve; RGR). Both impala and kudu had significantly higher FGM levels in the area that allows hunting, while FGM levels decreased with increasing forage availability and increasing daily temperature. Moreover, impala (but not kudu) had lower FGM levels with larger group sizes. Our results indicate that the management regime can significantly alter the physiological state of wild ungulate populations. We also highlight the importance of considering the combined effects of anthropogenic, environmental and social contexts when studying the stress response of wild populations. Our results emphasize the value of protected areas and continued monitoring of hunting quota in order to maintain ungulate populations that are less vulnerable to population declines.
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Affiliation(s)
- Kwaslema Malle Hariohay
- Department of Wildlife Management, College of African Wildlife Management, Mweka, P. O. Box 3031, Moshi, Tanzania
- Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491, Trondheim, Norway
| | - Louis Hunninck
- Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491, Trondheim, Norway
- Department of Natural Resources and Environmental Sciences, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Peter S Ranke
- Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491, Trondheim, Norway
- Center for Biodiversity Dynamics (CBD), Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491, Trondheim, Norway
| | - Robert D Fyumagwa
- Department of Wildlife Management, Tanzania Wildlife Research Institute (TAWIRI), P.O. Box 661, Arusha
| | - Rupert Palme
- Department of Biomedical Sciences, University of Veterinary Medicine, Vienna
| | - Eivin Røskaft
- Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491, Trondheim, Norway
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Using camera trap bycatch data to assess habitat use and the influence of human activity on African elephants (Loxodonta africana) in Kasungu National Park, Malawi. Mamm Biol 2022. [DOI: 10.1007/s42991-022-00330-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AbstractAfrican elephants (Loxodonta africana) are increasingly exposed to high levels of human disturbance and are threatened by poaching and human–elephant conflict. As anthropogenic pressures continue to increase, both inside and outside protected areas, understanding elephant behavioural responses to human activity is required for future conservation management. Here, we use bycatch data from camera trap surveys to provide inferences on elephant habitat use and temporal activity in Kasungu National Park (KNP), Malawi. The KNP elephant population has declined by ~ 95% since the late 1970s, primarily because of intensive poaching, and information on elephant ecology and behaviour can assist in the species’ recovery. Using occupancy modelling, we show that proximity to water is the primary driver of elephant habitat use in KNP, with sites closer to water having a positive effect on elephant site use. Our occupancy results suggest that elephants do not avoid sites of higher human activity, while results from temporal activity models show that elephants avoid peak times of human activity and exhibit primarily nocturnal behaviour when using the KNP road network. As key park infrastructure is located near permanent water sources, elephant spatiotemporal behaviour may represent a trade-off between resource utilisation and anthropogenic-risk factors, with temporal partitioning used to reduce encounter rates. Increased law enforcement activity around permanent water sources could help to protect the KNP elephant population during the dry season. Our findings highlight that camera trap bycatch data can be a useful tool for the conservation management of threatened species beyond the initial scope of research.
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Parker JM, Brown JL, Hobbs NT, Boisseau NP, Letitiya D, Douglas-Hamilton I, Wittemyer G. Social support correlates with glucocorticoid concentrations in wild African elephant orphans. Commun Biol 2022; 5:630. [PMID: 35835816 PMCID: PMC9283395 DOI: 10.1038/s42003-022-03574-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 06/10/2022] [Indexed: 12/25/2022] Open
Abstract
Social relationships have physiological impacts. Here, we investigate whether loss of the mother/offspring relationship has lasting effects on fecal glucocorticoid metabolite (fGCM) concentrations in wild African elephant orphans several years following their mothers’ deaths. We find no difference in fGCM concentrations between orphans and nonorphans, but find lower fGCM concentrations in elephants with more age mates in their family. We also unexpectedly identify lower concentrations in orphans without their natal family versus nonorphans and natal orphans, which we speculate may be due to the development of hypocortisolism following a prolonged period without familial support. An index of plant productivity (i.e. food) shows the largest correlation with fGCM concentrations. Our findings indicate no lasting differences in glucocorticoid concentrations of surviving orphan elephants who are with their family, suggest the presence of age mates may reduce glucocorticoid concentrations in elephants, and emphasize that basic survival needs are the primary regulators of the stress response. Remaining with the family group may reduce long-term stress effects in orphaned African elephants.
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Affiliation(s)
- J M Parker
- Graduate Degree Program in Ecology, Colorado State University, 102 Johnson Hall, Fort Collins, CO, 80523, USA. .,Department of Fish, Wildlife and Conservation Biology, Colorado State University, 1474 Campus Delivery, Fort Collins, CO, 80523, USA. .,Save the Elephants, Marula Manor, Marula Lane, Karen, Nairobi, 00200, Kenya.
| | - J L Brown
- Center for Species Survival, Smithsonian Conservation Biology Institute, 1500 Remount Road, Front Royal, VA, 22630, USA
| | - N T Hobbs
- Graduate Degree Program in Ecology, Colorado State University, 102 Johnson Hall, Fort Collins, CO, 80523, USA.,Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80523, USA
| | - N P Boisseau
- Center for Species Survival, Smithsonian Conservation Biology Institute, 1500 Remount Road, Front Royal, VA, 22630, USA
| | - D Letitiya
- Save the Elephants, Marula Manor, Marula Lane, Karen, Nairobi, 00200, Kenya
| | - I Douglas-Hamilton
- Save the Elephants, Marula Manor, Marula Lane, Karen, Nairobi, 00200, Kenya.,Department of Zoology, Oxford University, Oxford, OX1 3PS, UK
| | - G Wittemyer
- Graduate Degree Program in Ecology, Colorado State University, 102 Johnson Hall, Fort Collins, CO, 80523, USA.,Department of Fish, Wildlife and Conservation Biology, Colorado State University, 1474 Campus Delivery, Fort Collins, CO, 80523, USA.,Save the Elephants, Marula Manor, Marula Lane, Karen, Nairobi, 00200, Kenya
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Observable Metabolites and Metabolomic Sampling Protocols for Managed African Savanna Elephant (Loxodonta africana) Whole Blood Using H-NMR Spectroscopy. Metabolites 2022; 12:metabo12050400. [PMID: 35629905 PMCID: PMC9143938 DOI: 10.3390/metabo12050400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 04/17/2022] [Accepted: 04/24/2022] [Indexed: 02/04/2023] Open
Abstract
We used nuclear magnetic spectroscopy (NMR) to evaluate the metabolomics of heparinized whole blood drawn from six African savanna elephants (Loxodonta africana) maintained on a well characterized diet. Whole blood samples obtained under behavioral restraint, then quickly frozen in liquid nitrogen, were stored at −80 °C until analysis. Frozen samples were thawed under controlled conditions and extracted with methanol and chloroform to separate the polar and non-polar metabolites. We identified 18 polar metabolites and 14 non-polar lipids using one-dimensional (1D) and two-dimensional (2D) NMR spectra. Despite unexpected rouleaux formation in the thawed frozen samples, spectra were consistent among animals and did not vary dramatically with age or the sex of the animal.
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Troup G, Heinsohn R, King LE, Edwards KL. Exploring seasonal variation in the faecal glucocorticoid concentrations of African elephants (Loxodonta africana) living in a drought-prone, anthropogenic landscape. WILDLIFE RESEARCH 2022. [DOI: 10.1071/wr21003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Mortimer B, Walker JA, Lolchuragi DS, Reinwald M, Daballen D. Noise matters: elephants show risk-avoidance behaviour in response to human-generated seismic cues. Proc Biol Sci 2021; 288:20210774. [PMID: 34187196 PMCID: PMC8242925 DOI: 10.1098/rspb.2021.0774] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
African elephants (Loxodonta africana) use many sensory modes to gather information about their environment, including the detection of seismic, or ground-based, vibrations. Seismic information is known to include elephant-generated signals, but also potentially encompasses biotic cues that are commonly referred to as ‘noise’. To investigate seismic information transfer in elephants beyond communication, here we tested the hypothesis that wild elephants detect and discriminate between seismic vibrations that differ in their noise types, whether elephant- or human-generated. We played three types of seismic vibrations to elephants: seismic recordings of elephants (elephant-generated), white noise (human-generated) and a combined track (elephant- and human-generated). We found evidence of both detection of seismic noise and discrimination between the two treatments containing human-generated noise. In particular, we found evidence of retreat behaviour, where seismic tracks with human-generated noise caused elephants to move further away from the trial location. We conclude that seismic noise are cues that contain biologically relevant information for elephants that they can associate with risk. This expands our understanding of how elephants use seismic information, with implications for elephant sensory ecology and conservation management.
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Affiliation(s)
- Beth Mortimer
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | - James A Walker
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | | | | | - David Daballen
- Save the Elephants, Marula Manor, Karen, Nairobi 00200, Kenya
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