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Huang RM, Maré C, Guldemond RAR, Pimm SL, van Aarde RJ. Protecting and connecting landscapes stabilizes populations of the Endangered savannah elephant. Sci Adv 2024; 10:eadk2896. [PMID: 38181078 PMCID: PMC10776014 DOI: 10.1126/sciadv.adk2896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Accepted: 12/01/2023] [Indexed: 01/07/2024]
Abstract
The influence of protected areas on the growth of African savannah elephant populations is inadequately known. Across southern Africa, elephant numbers grew at 0.16% annually for the past quarter century. Locally, much depends on metapopulation dynamics-the size and connections of individual populations. Population numbers in large, connected, and strictly protected areas typically increased, were less variable from year to year, and suffered less from poaching. Conversely, populations in buffer areas that are less protected but still connected have more variation in growth from year to year. Buffer areas also differed more in their growth rates, likely due to more threats and dispersal opportunities in the face of such dangers. Isolated populations showed consistently high growth due to a lack of emigration. This suggests that "fortress" conservation generally maintains high growth, while anthropogenic-driven source-sink dynamics within connected conservation clusters drive stability in core areas and variability in buffers.
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Affiliation(s)
- Ryan M. Huang
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
| | - Celesté Maré
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
| | - Robert A. R. Guldemond
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
| | - Stuart L. Pimm
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
- Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - Rudi J. van Aarde
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
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2
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de Flamingh A, Ishida Y, Pečnerová P, Vilchis S, Siegismund HR, van Aarde RJ, Malhi RS, Roca AL. Combining methods for non-invasive fecal DNA enables whole genome and metagenomic analyses in wildlife biology. Front Genet 2023; 13:1021004. [PMID: 36712847 PMCID: PMC9876978 DOI: 10.3389/fgene.2022.1021004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 12/05/2022] [Indexed: 01/13/2023] Open
Abstract
Non-invasive biological samples benefit studies that investigate rare, elusive, endangered, or dangerous species. Integrating genomic techniques that use non-invasive biological sampling with advances in computational approaches can benefit and inform wildlife conservation and management. Here, we used non-invasive fecal DNA samples to generate low- to medium-coverage genomes (e.g., >90% of the complete nuclear genome at six X-fold coverage) and metagenomic sequences, combining widely available and accessible DNA collection cards with commonly used DNA extraction and library building approaches. DNA preservation cards are easy to transport and can be stored non-refrigerated, avoiding cumbersome or costly sample methods. The genomic library construction and shotgun sequencing approach did not require enrichment or targeted DNA amplification. The utility and potential of the data generated was demonstrated through genome scale and metagenomic analyses of zoo and free-ranging African savanna elephants (Loxodonta africana). Fecal samples collected from free-ranging individuals contained an average of 12.41% (5.54-21.65%) endogenous elephant DNA. Clustering of these elephants with others from the same geographic region was demonstrated by a principal component analysis of genetic variation using nuclear genome-wide SNPs. Metagenomic analyses identified taxa that included Loxodonta, green plants, fungi, arthropods, bacteria, viruses and archaea, showcasing the utility of this approach for addressing complementary questions based on host-associated DNA, e.g., pathogen and parasite identification. The molecular and bioinformatic analyses presented here contributes towards the expansion and application of genomic techniques to conservation science and practice.
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Affiliation(s)
- Alida de Flamingh
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States,*Correspondence: Alida de Flamingh, ; Ripan S. Malhi, ; Alfred L. Roca,
| | - Yasuko Ishida
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Patrícia Pečnerová
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Sahara Vilchis
- Department of Anthropology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Hans R. Siegismund
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rudi J. van Aarde
- Department of Zoology and Entomology, Conservation Ecology Research Unit, University of Pretoria, Pretoria, South Africa
| | - Ripan S. Malhi
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States,Department of Anthropology, University of Illinois at Urbana-Champaign, Urbana, IL, United States,*Correspondence: Alida de Flamingh, ; Ripan S. Malhi, ; Alfred L. Roca,
| | - Alfred L. Roca
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States,Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States,*Correspondence: Alida de Flamingh, ; Ripan S. Malhi, ; Alfred L. Roca,
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3
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Huang RM, van Aarde RJ, Pimm SL, Chase MJ, Leggett K. Mapping potential connections between Southern Africa's elephant populations. PLoS One 2022; 17:e0275791. [PMID: 36219597 PMCID: PMC9553058 DOI: 10.1371/journal.pone.0275791] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 09/20/2022] [Indexed: 11/07/2022] Open
Abstract
Southern Africa spans nearly 7 million km2 and contains approximately 80% of the world’s savannah elephants (Loxodonta africana) mostly living in isolated protected areas. Here we ask what are the prospects for improving the connections between these populations? We combine 1.2 million telemetry observations from 254 elephants with spatial data on environmental factors and human land use across eight southern African countries. Telemetry data show what natural features limit elephant movement and what human factors, including fencing, further prevent or restrict dispersal. The resulting intersection of geospatial data and elephant presences provides a map of suitable landscapes that are environmentally appropriate for elephants and where humans allow elephants to occupy. We explore the environmental and anthropogenic constraints in detail using five case studies. Lastly, we review all the major potential connections that may remain to connect a fragmented elephant metapopulation and document connections that are no longer feasible.
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Affiliation(s)
- Ryan M. Huang
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
- * E-mail: (RMH); (RJA)
| | - Rudi J. van Aarde
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
- * E-mail: (RMH); (RJA)
| | - Stuart L. Pimm
- Nicholas School of the Environment, Duke University, Durham, North Carolina, United States of America
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, South Africa
| | | | - Keith Leggett
- Fowlers Gap Arid Zone Research Station, UNSW Sydney, Sydney, Fowlers Gap, Australia
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Guldemond RAR, Louw CJ, Maré C, Nørgaard C, van Aarde RJ. Demographic responses of an insular elephant population to removal as a management intervention. Conservat Sci and Prac 2022. [DOI: 10.1111/csp2.12741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Affiliation(s)
- Robert A. R. Guldemond
- Conservation Ecology Research Unit, Department of Zoology & Entomology University of Pretoria Hatfield South Africa
| | - Cornelius J. Louw
- Conservation Ecology Research Unit, Department of Zoology & Entomology University of Pretoria Hatfield South Africa
| | - Celesté Maré
- Conservation Ecology Research Unit, Department of Zoology & Entomology University of Pretoria Hatfield South Africa
| | - Camilla Nørgaard
- Conservation Ecology Research Unit, Department of Zoology & Entomology University of Pretoria Hatfield South Africa
| | - Rudi J. van Aarde
- Conservation Ecology Research Unit, Department of Zoology & Entomology University of Pretoria Hatfield South Africa
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Abstract
The cause of deaths of 350 elephants in 2020 in a relatively small unprotected area of northern Botswana is unknown, and may never be known. Media speculations about it ignore ecological realities. Worse, they make conjectures that can be detrimental to wildlife and sometimes discredit conservation incentives. A broader understanding of the ecological and conservation issues speaks to elephant management across the Kavango–Zambezi Transfrontier Conservation Area that extends across Botswana, Namibia, Angola, Zambia, and Zimbabwe. Our communication addresses these. Malicious poisoning and poaching are unlikely to have played a role. Other species were unaffected, and elephant carcases had their tusks intact. Restriction of freshwater supplies that force elephants to use pans as a water source possibly polluted by blue-green algae blooms is a possible cause, but as yet not supported by evidence. No other species were involved. A contagious disease is the more probable one. Fences and a deep channel of water confine these elephants’ dispersal. These factors explain the elephants’ relatively high population growth rate despite a spell of increased poaching during 2014–2018. While the deaths represent only ~2% of the area’s elephants, the additive effects of poaching and stress induced by people protecting their crops cause alarm. Confinement and relatively high densities probably explain why the die-off occurred only here. It suggests a re-alignment or removal of fences that restrict elephant movements and limits year-round access to freshwater.
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Affiliation(s)
- Rudi J van Aarde
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, Gauteng, South Africa
| | - Stuart L Pimm
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, Gauteng, South Africa.,Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - Robert Guldemond
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, Gauteng, South Africa
| | - Ryan Huang
- Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - Celesté Maré
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, Gauteng, South Africa
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Purdon A, Mole MA, Chase MJ, van Aarde RJ. Partial migration in savanna elephant populations distributed across southern Africa. Sci Rep 2018; 8:11331. [PMID: 30054547 PMCID: PMC6063881 DOI: 10.1038/s41598-018-29724-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 07/16/2018] [Indexed: 11/09/2022] Open
Abstract
Migration is an important, but threatened ecological process. Conserving migration requires the maintenance of functional connectivity across sufficiently large areas. Therefore, we need to know if, where and why species migrate. Elephants are highly mobile and can travel long distances but we do not know if they migrate. Here, we analysed the movement trajectories of 139 savanna elephants (Loxodonta africana) within eight clusters of protected areas across southern Africa to determine if elephants migrate, and if so, where, how and why they migrate. Only 25 of these elephants migrated. Elephants are a facultative partially migratory species, where only some individuals in a population migrate opportunistically, and not every year. Elephants migrated between distinct seasonal ranges corresponding to southern Africa’s dry and wet seasons. The timing of wet season migrations was associated with the onset of rainfall and the subsequent greening up of forage. Conversely, the duration, distance, and the timing of dry season migrations varied idiosyncratically. The drivers of elephant migration are likely a complex interaction between individual traits, density, and the distribution and availability of resources. Despite most migrations crossing administrative boundaries, conservation networks provided functional space for elephants to migrate.
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Affiliation(s)
- Andrew Purdon
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0028, South Africa
| | - Michael A Mole
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0028, South Africa
| | | | - Rudi J van Aarde
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0028, South Africa.
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7
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Mole MA, Rodrigues DÁraujo S, van Aarde RJ, Mitchell D, Fuller A. Savanna elephants maintain homeothermy under African heat. J Comp Physiol B 2018; 188:889-897. [DOI: 10.1007/s00360-018-1170-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 06/06/2018] [Accepted: 07/02/2018] [Indexed: 12/01/2022]
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8
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McClelland GTW, Altwegg R, van Aarde RJ, Ferreira S, Burger AE, Chown SL. Climate change leads to increasing population density and impacts of a key island invader. Ecol Appl 2018; 28:212-224. [PMID: 29055070 DOI: 10.1002/eap.1642] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/02/2017] [Indexed: 06/07/2023]
Abstract
The considerable threats of invasive rodents to island biodiversity are likely to be compounded by climate change. Forecasts for such interactions have been most pronounced for the Southern Ocean islands where ameliorating conditions are expected to decrease thermal and resource restrictions on rodents. Firm evidence for changing rodent populations in response to climate change, and demonstrations of associated impacts on the terrestrial environment, are nonetheless entirely absent for the region. Using data collected over three decades on sub-Antarctic Marion Island, we tested empirically whether mouse populations have changed through time and whether these changes can be associated significantly with changing abiotic conditions. Changes in invertebrate populations, which have previously been attributed to mouse predation, but with little explicit demographic analysis, were also examined to determine whether they can be associated with changing mouse populations. The total number of mice on the island at annual peak density increased by 430.0% between 1979-1980 and 2008-2011. This increase was due to an advanced breeding season, which was robustly related to the number of precipitation-free days during the non-breeding season. Mice directly reduced invertebrate densities, with biomass losses of up to two orders of magnitude in some habitats. Such invertebrate declines are expected to have significant consequences for ecosystem processes over the long term. Our results demonstrate that as climate change continues to create ameliorating conditions for invasive rodents on sub-Antarctic islands, the severity of their impacts will increase. They also emphasize the importance of rodent eradication for the restoration of invaded islands.
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Affiliation(s)
- Gregory T W McClelland
- Department of Botany and Zoology, Centre for Invasion Biology, Stellenbosch University, Matieland, South Africa
| | - Res Altwegg
- Department of Statistical Sciences, Centre for Statistics in Ecology, Environment and Conservation, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa
- African Climate and Development Initiative, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa
| | - Rudi J van Aarde
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, Pretoria, 0083, South Africa
| | - Sam Ferreira
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Hatfield, Pretoria, 0083, South Africa
- Scientific Services, SANParks, Kruger National Park, South Africa
| | - Alan E Burger
- Department of Biology, University of Victoria, Victoria, British Columbia, V8W 3N5, Canada
| | - Steven L Chown
- School of Biological Sciences, Monash University, Victoria, 3800, Australia
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9
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Abstract
Contradictory findings among scientific studies that address a particular issue may impede the conversion of science to management implementation. A systematic review of peer-reviewed studies to generate a single outcome may overcome this problem. The contentious topic of the impact that a megaherbivore such as the savanna elephant have for other species and their environment can benefit from such an approach. After some 68 years, 367 peer-reviewed papers covered the topic and 51 of these papers provided sufficient data to be included in a meta-analysis. We separated the direct impact that elephants had on trees and herbs from the indirect effects on other vertebrates, invertebrates, and soil properties. Elephants have an impact on tree structure and abundance but no overall negative cascading effects for species that share space with them. Primary productivity explained a small amount of variation of elephant impact on vegetation. Elephant numbers (density), study duration, rainfall, tree cover, and the presence of artificial water and fences failed to describe patterns of impact. We conclude that published information do not support the calls made for artificially manipulating elephant numbers to ameliorate elephant impact, and call for the management of space use by elephants to maintain savanna heterogeneity.
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Affiliation(s)
- Robert A. R. Guldemond
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Andrew Purdon
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Rudi J. van Aarde
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
- * E-mail:
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10
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Olivier PI, Rolo V, van Aarde RJ. Pattern or process? Evaluating the peninsula effect as a determinant of species richness in coastal dune forests. PLoS One 2017; 12:e0173694. [PMID: 28376096 PMCID: PMC5380308 DOI: 10.1371/journal.pone.0173694] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 02/26/2017] [Indexed: 11/18/2022] Open
Abstract
The peninsula effect predicts that the number of species should decline from the base of a peninsula to the tip. However, evidence for the peninsula effect is ambiguous, as different analytical methods, study taxa, and variations in local habitat or regional climatic conditions influence conclusions on its presence. We address this uncertainty by using two analytical methods to investigate the peninsula effect in three taxa that occupy different trophic levels: trees, millipedes, and birds. We surveyed 81 tree quadrants, 102 millipede transects, and 152 bird points within 150 km of coastal dune forest that resemble a habitat peninsula along the northeast coast of South Africa. We then used spatial (trend surface analyses) and non-spatial regressions (generalized linear mixed models) to test for the presence of the peninsula effect in each of the three taxa. We also used linear mixed models to test if climate (temperature and precipitation) and/or local habitat conditions (water availability associated with topography and landscape structural variables) could explain gradients in species richness. Non-spatial models suggest that the peninsula effect was present in all three taxa. However, spatial models indicated that only bird species richness declined from the peninsula base to the peninsula tip. Millipede species richness increased near the centre of the peninsula, while tree species richness increased near the tip. Local habitat conditions explained species richness patterns of birds and trees, but not of millipedes, regardless of model type. Our study highlights the idiosyncrasies associated with the peninsula effect-conclusions on the presence of the peninsula effect depend on the analytical methods used and the taxon studied. The peninsula effect might therefore be better suited to describe a species richness pattern where the number of species decline from a broader habitat base to a narrow tip, rather than a process that drives species richness.
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Affiliation(s)
- Pieter I. Olivier
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, Hatfield, South Africa
- * E-mail:
| | - Victor Rolo
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, Hatfield, South Africa
| | - Rudi J. van Aarde
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, Hatfield, South Africa
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11
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Olivier PI, van Aarde RJ. The response of bird feeding guilds to forest fragmentation reveals conservation strategies for a critically endangered African eco-region. Biotropica 2016. [DOI: 10.1111/btp.12402] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Pieter I. Olivier
- Conservation Ecology Research Unit; Department of Zoology and Entomology; University of Pretoria; Hatfield 0083 South Africa
| | - Rudi J. van Aarde
- Conservation Ecology Research Unit; Department of Zoology and Entomology; University of Pretoria; Hatfield 0083 South Africa
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12
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Mole MA, Rodrigues DÁraujo S, van Aarde RJ, Mitchell D, Fuller A. Coping with heat: behavioural and physiological responses of savanna elephants in their natural habitat. Conserv Physiol 2016; 4:cow044. [PMID: 27757237 PMCID: PMC5066386 DOI: 10.1093/conphys/cow044] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 09/06/2016] [Accepted: 09/11/2016] [Indexed: 05/19/2023]
Abstract
Most of southern Africa's elephants inhabit environments where environmental temperatures exceed body temperature, but we do not know how elephants respond to such environments. We evaluated the relationships between apparent thermoregulatory behaviour and environmental, skin and core temperatures for tame savanna elephants (Loxodonta africana) that were free-ranging in the hot parts of the day, in their natural environment. Environmental temperature dictated elephant behaviour within a day, with potential consequences for fine-scale habitat selection, space use and foraging. At black globe temperatures of ~30°C, elephants adjusted their behaviour to reduce environmental heat load and increase heat dissipation (e.g. shade use, wetting behaviour). Resting, walking and feeding were also influenced by environmental temperature. By relying on behavioural and autonomic adjustments, the elephants maintained homeothermy, even at environmental temperatures exceeding 40°C. Elephants clearly have the capacity to deal with extreme heat, at least in environments with adequate resources of forage, water and shade. Future conservation actions should provide for the thermoregulatory, resource and spatial needs of elephants.
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Affiliation(s)
- Michael A Mole
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Shaun Rodrigues DÁraujo
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Rudi J van Aarde
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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13
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de Flamingh A, Sole CL, van Aarde RJ. Genetic evidence for spatial structuring in a continuous African elephant (Loxodonta africana) population. CONSERV GENET 2014. [DOI: 10.1007/s10592-014-0686-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Mashintonio AF, Pimm SL, Harris GM, van Aarde RJ, Russell GJ. Data-driven discovery of the spatial scales of habitat choice by elephants. PeerJ 2014; 2:e504. [PMID: 25177532 PMCID: PMC4145068 DOI: 10.7717/peerj.504] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 07/15/2014] [Indexed: 11/20/2022] Open
Abstract
Setting conservation goals and management objectives relies on understanding animal habitat preferences. Models that predict preferences combine location data from tracked animals with environmental information, usually at a spatial resolution determined by the available data. This resolution may be biologically irrelevant for the species in question. Individuals likely integrate environmental characteristics over varying distances when evaluating their surroundings; we call this the scale of selection. Even a single characteristic might be viewed differently at different scales; for example, a preference for sheltering under trees does not necessarily imply a fondness for continuous forest. Multi-scale preference is likely to be particularly evident for animals that occupy coarsely heterogeneous landscapes like savannahs. We designed a method to identify scales at which species respond to resources and used these scales to build preference models. We represented different scales of selection by locally averaging, or smoothing, the environmental data using kernels of increasing radii. First, we examined each environmental variable separately across a spectrum of selection scales and found peaks of fit. These 'candidate' scales then determined the environmental data layers entering a multivariable conditional logistic model. We used model selection via AIC to determine the important predictors out of this set. We demonstrate this method using savannah elephants (Loxodonta africana) inhabiting two parks in southern Africa. The multi-scale models were more parsimonious than models using environmental data at only the source resolution. Maps describing habitat preferences also improved when multiple scales were included, as elephants were more often in places predicted to have high neighborhood quality. We conclude that elephants select habitat based on environmental qualities at multiple scales. For them, and likely many other species, biologists should include multiple scales in models of habitat selection. Species environmental preferences and their geospatial projections will be more accurately represented, improving management decisions and conservation planning.
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Affiliation(s)
| | - Stuart L Pimm
- Nicholas School of Environmental Science, Duke University , Durham, NC , USA
| | - Grant M Harris
- United States Fish and Wildlife Service , Albuquerque, NM , USA
| | - Rudi J van Aarde
- Conservation Ecology Research Unit, University of Pretoria , Pretoria , South Africa
| | - Gareth J Russell
- Department of Biological Sciences, Rutgers University , Newark, NJ , USA ; Department of Biological Sciences, New Jersey Institute of Technology , Newark, NJ , USA
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15
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de Flamingh A, Sole CL, van Aarde RJ. Microsatellite repeat motif and amplicon length affect amplification success of degraded faecal DNA. CONSERV GENET RESOUR 2014. [DOI: 10.1007/s12686-014-0160-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Affiliation(s)
- Morgan J. Trimble
- Conservation Ecology Research Unit; Department of Zoology & Entomology; University of Pretoria; Private Bag X20; Hatfield Pretoria; 0028; South Africa
| | - Rudi J. van Aarde
- Conservation Ecology Research Unit; Department of Zoology & Entomology; University of Pretoria; Private Bag X20; Hatfield Pretoria; 0028; South Africa
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17
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Olivier PI, van Aarde RJ, Lombard AT. The use of habitat suitability models and species-area relationships to predict extinction debts in coastal forests, South Africa. DIVERS DISTRIB 2013. [DOI: 10.1111/ddi.12099] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Pieter I. Olivier
- Conservation Ecology Research Unit; Department of Zoology and Entomology; University of Pretoria; Pretoria South Africa
| | - Rudi J. van Aarde
- Conservation Ecology Research Unit; Department of Zoology and Entomology; University of Pretoria; Pretoria South Africa
| | - Amanda T. Lombard
- Conservation Ecology Research Unit; Department of Zoology and Entomology; University of Pretoria; Pretoria South Africa
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18
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Ott T, van Aarde RJ. Coastal dune topography as a determinant of abiotic conditions and biological community restoration in northern KwaZulu-Natal, South Africa. Landscape Ecol Eng 2013. [DOI: 10.1007/s11355-013-0211-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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20
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Affiliation(s)
- Matthew J. Grainger
- Conservation Ecology Research Unit; Department of Zoology and Entomology; University of Pretoria; Pretoria; Private Bag ×20; Hatfield; 0028; South Africa
| | - Rudi J. van Aarde
- Conservation Ecology Research Unit; Department of Zoology and Entomology; University of Pretoria; Pretoria; Private Bag ×20; Hatfield; 0028; South Africa
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Trimble MJ, van Aarde RJ, Ferreira SM, Nørgaard CF, Fourie J, Lee PC, Moss CJ. Age determination by back length for African savanna elephants: extending age assessment techniques for aerial-based surveys. PLoS One 2011; 6:e26614. [PMID: 22028925 PMCID: PMC3197571 DOI: 10.1371/journal.pone.0026614] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 09/29/2011] [Indexed: 11/18/2022] Open
Abstract
Determining the age of individuals in a population can lead to a better understanding of population dynamics through age structure analysis and estimation of age-specific fecundity and survival rates. Shoulder height has been used to accurately assign age to free-ranging African savanna elephants. However, back length may provide an analog measurable in aerial-based surveys. We assessed the relationship between back length and age for known-age elephants in Amboseli National Park, Kenya, and Addo Elephant National Park, South Africa. We also compared age- and sex-specific back lengths between these populations and compared adult female back lengths across 11 widely dispersed populations in five African countries. Sex-specific Von Bertalanffy growth curves provided a good fit to the back length data of known-age individuals. Based on back length, accurate ages could be assigned relatively precisely for females up to 23 years of age and males up to 17. The female back length curve allowed more precise age assignment to older females than the curve for shoulder height does, probably because of divergence between the respective growth curves. However, this did not appear to be the case for males, but the sample of known-age males was limited to ≤27 years. Age- and sex-specific back lengths were similar in Amboseli National Park and Addo Elephant National Park. Furthermore, while adult female back lengths in the three Zambian populations were generally shorter than in other populations, back lengths in the remaining eight populations did not differ significantly, in support of claims that growth patterns of African savanna elephants are similar over wide geographic regions. Thus, the growth curves presented here should allow researchers to use aerial-based surveys to assign ages to elephants with greater precision than previously possible and, therefore, to estimate population variables.
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Affiliation(s)
- Morgan J. Trimble
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Rudi J. van Aarde
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
- * E-mail:
| | - Sam M. Ferreira
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
- Scientific Services, South African National Parks, Skukuza, South Africa
| | - Camilla F. Nørgaard
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Johan Fourie
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Phyllis C. Lee
- Amboseli Trust for Elephants, Nairobi, Kenya
- Behaviour and Evolution Research Group, School of Natural Sciences, University of Stirling, Stirling, United Kingdom
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Ferreira SM, Aarde RJV. Aerial Survey Intensity as a Determinant of Estimates of African Elephant Population Sizes and Trends. ACTA ACUST UNITED AC 2009. [DOI: 10.3957/056.039.0205] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Haim A, Zubidat AE, van Aarde RJ. Daily rhythms of body temperature and heat production of sibling mastomys species from different ecosystems — The response to photoperiod manipulations. Comp Biochem Physiol A Mol Integr Physiol 2008; 151:505-10. [DOI: 10.1016/j.cbpa.2008.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2008] [Revised: 06/30/2008] [Accepted: 07/02/2008] [Indexed: 10/21/2022]
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Ntshotsho P, van Aarde RJ, Nicolson SW, Jackson TP. Renal physiology of two southern African Mastomys species (Rodentia: Muridae): a salt-loading experiment to assess concentrating ability. Comp Biochem Physiol A Mol Integr Physiol 2004; 139:441-7. [PMID: 15596389 DOI: 10.1016/j.cbpb.2004.09.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Revised: 09/27/2004] [Accepted: 09/27/2004] [Indexed: 11/18/2022]
Abstract
Aspects of renal physiology were examined to test the hypothesis that two cryptic species of the genus Mastomys (Mastomys natalensis and Mastomys coucha) are geographically separated by differences in aridity tolerance. Laboratory-bred females of each species were subjected to different levels of salinity in their water source (distilled water, 0.9% NaCl, and 1.5% NaCl; 10 conspecifics in each group) from weaning until sexual maturity. Individuals of the two species exhibited similar rates of water consumption and urine production. The salinity treatments caused sodium diuresis in both species, evident in increased urine volume, decreased osmolality and increased osmotic output. Urine concentration, kidney mass and kidney relative medullary area (RMA) did not differ between species. The results of our study do not support the hypothesis that differences in osmoregulatory ability separate these two cryptic species. Nor do they support the use of salt loading to elicit maximum urine concentrations in mammals.
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Affiliation(s)
- Phumza Ntshotsho
- Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
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Jackson TP, van Aarde RJ. SEX- AND SPECIES-SPECIFIC GROWTH PATTERNS IN CRYPTIC AFRICAN RODENTS, MASTOMYS NATALENSIS AND M. COUCHA. J Mammal 2003. [DOI: 10.1644/bpr-001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Davis ALV, van Aarde RJ, Scholtz CH, Delport JH. Convergence Between Dung Beetle Assemblages of a Post-Mining Vegetational Chronosequence and Unmined Dune Forest. Restor Ecol 2003. [DOI: 10.1046/j.1526-100x.2003.00133.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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