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Cordier CP, Smith DAE, Smith YE, Downs CT. Camera trap research in Africa: A systematic review to show trends in wildlife monitoring and its value as a research tool. Glob Ecol Conserv 2022. [DOI: 10.1016/j.gecco.2022.e02326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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2
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Daskin JH, Becker JA, Kartzinel TR, Potter AB, Walker RH, Eriksson FAA, Buoncore C, Getraer A, Long RA, Pringle RM. Allometry of behavior and niche differentiation among congeneric African antelopes. ECOL MONOGR 2022. [DOI: 10.1002/ecm.1549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Joshua H. Daskin
- Department of Ecology & Evolutionary Biology Princeton University Princeton NJ USA
- Archbold Biological Station Venus FL USA
| | - Justine A. Becker
- Department of Ecology & Evolutionary Biology Princeton University Princeton NJ USA
- Department of Zoology & Physiology University of Wyoming Laramie WY USA
| | - Tyler R. Kartzinel
- Department of Ecology & Evolutionary Biology Brown University Providence RI USA
| | - Arjun B. Potter
- Department of Ecology & Evolutionary Biology Princeton University Princeton NJ USA
| | - Reena H. Walker
- Department of Fish and Wildlife Sciences University of Idaho Moscow ID USA
| | | | - Courtney Buoncore
- Department of Ecology & Evolutionary Biology Princeton University Princeton NJ USA
| | - Alexander Getraer
- Department of Ecology & Evolutionary Biology Princeton University Princeton NJ USA
| | - Ryan A. Long
- Department of Fish and Wildlife Sciences University of Idaho Moscow ID USA
| | - Robert M. Pringle
- Department of Ecology & Evolutionary Biology Princeton University Princeton NJ USA
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3
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Zhong Z, Li G, Sanders D, Wang D, Holt RD, Zhang Z. A rodent herbivore reduces its predation risk through ecosystem engineering. Curr Biol 2022; 32:1869-1874.e4. [PMID: 35278348 DOI: 10.1016/j.cub.2022.02.074] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/27/2022] [Accepted: 02/25/2022] [Indexed: 11/18/2022]
Abstract
Predator-prey interactions are ubiquitous and powerful forces that structure ecological communities.1-3 Habitat complexity has been shown to be particularly important in regulating the strength of predator-prey interactions.4-6 While it is well established that changes in habitat structure can alter the efficacy of predatory and anti-predatory behaviors,7-9 little is known about the consequences of engineering activity by prey species who modify the external environment to reduce their own predation risk. Using field surveys and manipulative experiments, we evaluated how habitat modification by Brandt's voles (Lasiopodomys brandtii) influences predation risk from a principal avian predator (shrike; Lanius spp.) in a steppe grassland, located in Inner Mongolia, China. We found that voles actively modify habitat structure by cutting down a large, unpalatable bunchgrass species (Achnatherum splendens) in the presence of shrikes, a behavior that disappeared when these avian predators were excluded experimentally. The damage activities of these voless dramatically decreased the volume of unpalatable grasses, which in turn reduced visitations by shrikes and thus mortality rates. Our study shows that herbivorous prey that act as ecosystem engineers can directly reduce their own predation risk by modifying habitat structure. Given the ubiquity of predation risks faced by consumers, and the likely ability of many consumers to alter the habitat structure in which they live, the interplay between predation risk and ecosystem engineering may be an important but unappreciated mechanism at play in natural communities.
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Affiliation(s)
- Zhiwei Zhong
- State Key Laboratory of Integrated Management on Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing 100101, China; Key Laboratory of Vegetation Ecology of the Ministry of Education, Institute of Grassland Science, Songnen Grassland Ecosystem National Observation and Research Station, Northeast Normal University, Changchun, Jilin 130024, China
| | - Guoliang Li
- State Key Laboratory of Integrated Management on Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing 100101, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dirk Sanders
- Environment and Sustainability Institute, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Deli Wang
- Key Laboratory of Vegetation Ecology of the Ministry of Education, Institute of Grassland Science, Songnen Grassland Ecosystem National Observation and Research Station, Northeast Normal University, Changchun, Jilin 130024, China
| | - Robert D Holt
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Zhibin Zhang
- State Key Laboratory of Integrated Management on Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing 100101, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China.
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4
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Development and validation of a spatially-explicit agent-based model for space utilization by African savanna elephants (Loxodonta africana) based on determinants of movement. Ecol Modell 2021. [DOI: 10.1016/j.ecolmodel.2021.109499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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5
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Can an herbivore affect where a top predator kills its prey by modifying woody vegetation structure? Oecologia 2020; 192:779-789. [PMID: 32060732 DOI: 10.1007/s00442-020-04617-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 02/06/2020] [Indexed: 10/25/2022]
Abstract
In large mammal communities, little is known about modification of interspecific interactions through habitat structure changes. We assessed the effects of African elephants (Loxodonta africana) on features of woody habitat structure that can affect predator-prey interactions. We then explored how this can influence where African lions (Panthera leo) kill their prey. Indeed, lions are stalk-and-ambush predators and habitat structure and concealment opportunities are assumed to influence their hunting success. During 2 years, in Hwange National Park, Zimbabwe, kill sites (n = 167) of GPS-collared lions were characterized (visibility distance for large mammals, distance to a potential ambush site and presence of elephant impacts). We compared characteristics of lion kill sites with characteristics of random sites (1) at a large scale (i.e. in areas intensively used by lions, n = 418) and (2) at the microhabitat scale (i.e. in the direct surrounding available habitat, < 150 m, n = 167). Elephant-impacted sites had a slightly higher visibility and a longer distance to a potential ambush site than non-impacted sites, but these relationships were characterized by a high variability. At large scale, kill sites were characterized by higher levels of elephant impacts compared to random sites. At microhabitat scale, compared to the direct nearby available habitat, kill sites were characterized by a reduced distance to a potential ambush site. We suggest a conceptual framework whereby the relative importance of habitat features and prey abundance could change upon the scale considered.
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Henley MD, Cook RM. The management dilemma: Removing elephants to save large trees. KOEDOE: AFRICAN PROTECTED AREA CONSERVATION AND SCIENCE 2019. [DOI: 10.4102/koedoe.v61i1.1564] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
The loss of large trees ( 5 m in height) in Africa’s protected areas is often attributed to the impact by savanna elephants (Loxodonta africana). Concerns have been raised over large tree mortality levels in protected areas such as South Africa’s Kruger National Park (KNP) and in the past, the need to manage its elephant population in order to preserve large trees and biodiversity as a whole. Our review aims to synthesise and discuss the complexities of managing elephants’ effects on the landscape to ensure the survival of large trees, as well as the application purposes of the various lethal and non-lethal elephant mitigation strategies. We further critically evaluate past management strategies, which have solely focused on controlling elephant numbers to protect large trees. Past mitigation strategies focused on managing elephant impact by directly reducing elephant numbers. However, maintaining elephant numbers at a pre-determined carrying capacity level did not prevent the loss of large trees. Research on large tree survival in African savannas has continually exposed the complexity of the situation, as large tree survival is influenced at various demographic stages. In some cases, a coalescence of historical factors may have resulted in what could be perceived as an aesthetically appealing savanna for managers and tourists alike. Furthermore, the past high density of surface water within the KNP homogenised elephant impact on large trees by increasing the encounter rate between elephants and large trees. Our review evaluates how current mitigation strategies have shifted from purely managing elephant numbers to managing elephant distribution across impact gradients, thereby promoting heterogeneity within the system. Additionally, we discuss each mitigation strategy’s occurrence at various landscape scales and its advantages and disadvantages when used to manage impact of elephant on large trees.Conservation implications: A variety of options exist to manage the effects that elephants have on large trees. These options range from large-scale landscape manipulation solutions to small-scale individual tree protection methods. Interactions between elephants and large trees are complex, however, and conservation managers need to consider the advantages and disadvantages of each mitigation strategy to protect large trees.
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Watson LH, Cameron MJ, Iifo F. Elephant herbivory of knob‐thorn (
Senegalia nigrescens
) and ivory palm (
Hyphaene petersiana
) in Bwabwata National Park, Caprivi, Namibia: The role of ivory palm as a biotic refuge. Afr J Ecol 2019. [DOI: 10.1111/aje.12681] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Laurence H. Watson
- Nature Conservation Program Nelson Mandela University George South Africa
| | - Michael J. Cameron
- Nature Conservation Program Nelson Mandela University George South Africa
| | - Fillemon Iifo
- Directorate of Scientific Services – CITES Office Ministry of Environment and Tourism Windhoek Namibia
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Sobratee N, Slotow R. A Critical Review of Lion Research in South Africa: The Impact of Researcher Perspective, Research Mode, and Power Structures on Outcome Bias and Implementation Gaps. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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9
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Leeuwis T, Peel M, de Boer WF. Complexity in African savannas: Direct, indirect, and cascading effects of animal densities, rainfall and vegetation availability. PLoS One 2018; 13:e0197149. [PMID: 29768481 PMCID: PMC5955549 DOI: 10.1371/journal.pone.0197149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 04/28/2018] [Indexed: 11/19/2022] Open
Abstract
Savanna ecosystems are popular subjects for interaction studies. Multiple studies have been done on the impact of elephants on vegetation, the impact of grass and browse availability on animal densities or on competition between herbivore species. Previous studies showed that elephant densities are frequently negatively correlated with densities of tall trees, and that browse and grass availability are correlated with browser and grazer density respectively. Additionally, a competition effect between browse and grass availability has been reported. These relationships are usually analysed by testing direct relationships between e.g., herbivore densities and food availability, without addressing competition effects or other indirect effects. In this study, multiple interactions in a savanna system have been analysed simultaneously using Partial Least Square-Path Modelling (PLS-PM) using mammal and vegetation data from three different wildlife reserves in southern KwaZulu-Natal. The results showed that the processes that three separate models for the three areas provided the best understanding of the importance of the different interactions. These models suggest that elephants had a negative impact on trees, but also on grass availability. The impact is stronger when elephants are not able to migrate during the dry season. Browsers and grazers were correlated with browse and grass availability, but competition between browse and grass was not detected. This study shows that due to the complexity of the interactions in an ecosystem and differences in environmental factors, these interactions are best studied per area. PLS-PM can be a useful tool for estimating direct, indirect, and cascading effects of changing animal densities in conservation areas.
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Affiliation(s)
- Tim Leeuwis
- Resource Ecology Group, Wageningen University, Droevendaalsesteeg 3a, Wageningen, The Netherlands
| | - Mike Peel
- Agricultural Research Council, Animal Production Institute, Nelspruit, South Africa
| | - Willem F. de Boer
- Resource Ecology Group, Wageningen University, Droevendaalsesteeg 3a, Wageningen, The Netherlands
- * E-mail:
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Coggan NV, Hayward MW, Gibb H. A global database and "state of the field" review of research into ecosystem engineering by land animals. J Anim Ecol 2018; 87:974-994. [PMID: 29488217 DOI: 10.1111/1365-2656.12819] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 01/17/2018] [Indexed: 01/17/2023]
Abstract
Ecosystem engineers have been widely studied for terrestrial systems, but global trends in research encompassing the range of taxa and functions have not previously been synthesised. We reviewed contemporary understanding of engineer fauna in terrestrial habitats and assessed the methods used to document patterns and processes, asking: (a) which species act as ecosystem engineers and with whom do they interact? (b) What are the impacts of ecosystem engineers in terrestrial habitats and how are they distributed? (c) What are the primary methods used to examine engineer effects and how have these developed over time? We considered the strengths, weaknesses and gaps in knowledge related to each of these questions and suggested a conceptual framework to delineate "significant impacts" of engineering interactions for all terrestrial animals. We collected peer-reviewed publications examining ecosystem engineer impacts and created a database of engineer species to assess experimental approaches and any additional covariates that influenced the magnitude of engineer impacts. One hundred and twenty-two species from 28 orders were identified as ecosystem engineers, performing five ecological functions. Burrowing mammals were the most researched group (27%). Half of all studies occurred in dry/arid habitats. Mensurative studies comparing sites with and without engineers (80%) were more common than manipulative studies (20%). These provided a broad framework for predicting engineer impacts upon abundance and species diversity. However, the roles of confounding factors, processes driving these patterns and the consequences of experimentally adjusting variables, such as engineer density, have been neglected. True spatial and temporal replication has also been limited, particularly for emerging studies of engineer reintroductions. Climate change and habitat modification will challenge the roles that engineers play in regulating ecosystems, and these will become important avenues for future research. We recommend future studies include simulation of engineer effects and experimental manipulation of engineer densities to determine the potential for ecological cascades through trophic and engineering pathways due to functional decline. We also recommend improving knowledge of long-term engineering effects and replication of engineer reintroductions across landscapes to better understand how large-scale ecological gradients alter the magnitude of engineering impacts.
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Affiliation(s)
- Nicole V Coggan
- Department of Zoology, School of Life Sciences, La Trobe University, Melbourne, VIC., Australia
| | - Matthew W Hayward
- Australian Wildlife Conservancy, Subiaco East, W.A., Australia.,School of the Environment, Bangor University, Wales, UK
| | - Heloise Gibb
- Department of Zoology, School of Life Sciences, La Trobe University, Melbourne, VIC., Australia
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11
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Scrubbing Up: Multi-Scale Investigation of Woody Encroachment in a Southern African Savannah. REMOTE SENSING 2017. [DOI: 10.3390/rs9050419] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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12
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Fullman TJ, Kiker GA, Gaylard A, Southworth J, Waylen P, Kerley GI. Elephants respond to resource trade-offs in an aseasonal system through daily and annual variability in resource selection. KOEDOE: AFRICAN PROTECTED AREA CONSERVATION AND SCIENCE 2017. [DOI: 10.4102/koedoe.v59i1.1326] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
Animals and humans regularly make trade-offs between competing objectives. In Addo Elephant National Park (AENP), elephants (Loxodonta africana) trade off selection of resources, while managers balance tourist desires with conservation of elephants and rare plants. Elephant resource selection has been examined in seasonal savannas, but is understudied in aseasonal systems like AENP. Understanding elephant selection may suggest ways to minimise management trade-offs. We evaluated how elephants select vegetation productivity, distance to water, slope and terrain ruggedness across time in AENP and used this information to suggest management strategies that balance the needs of tourists and biodiversity. Resource selection functions with time-interacted covariates were developed for female elephants, using three data sets of daily movement to capture circadian and annual patterns of resource use. Results were predicted in areas of AENP currently unavailable to elephants to explore potential effects of future elephant access. Elephants displayed dynamic resource selection at daily and annual scales to meet competing requirements for resources. In summer, selection patterns generally conformed to those seen in savannas, but these relationships became weaker or reversed in winter. At daily scales, resource selection in the morning differed from that of midday and afternoon, likely reflecting trade-offs between acquiring sufficient forage and water. Dynamic selection strategies exist even in an aseasonal system, with both daily and annual patterns. This reinforces the importance of considering changing resource availability and trade-offs in studies of animal selection.Conservation implications: Guiding tourism based on knowledge of elephant habitat selection may improve viewing success without requiring increased elephant numbers. If AENP managers expand elephant habitat to reduce density, our model predicts where elephant use may concentrate and where botanical reserves may be needed to protect rare plants from elephant impacts.
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Davies AB, Tambling CJ, Kerley GIH, Asner GP. Limited spatial response to direct predation risk by African herbivores following predator reintroduction. Ecol Evol 2016; 6:5728-48. [PMID: 27547350 PMCID: PMC4983587 DOI: 10.1002/ece3.2312] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 06/07/2016] [Accepted: 06/16/2016] [Indexed: 12/03/2022] Open
Abstract
Predators affect ecosystems not only through direct mortality of prey, but also through risk effects on prey behavior, which can exert strong influences on ecosystem function and prey fitness. However, how functionally different prey species respond to predation risk and how prey strategies vary across ecosystems and in response to predator reintroduction are poorly understood. We investigated the spatial distributions of six African herbivores varying in foraging strategy and body size in response to environmental factors and direct predation risk by recently reintroduced lions in the thicket biome of the Addo Elephant National Park, South Africa, using camera trap surveys, GPS telemetry, kill site locations and Light Detection and Ranging. Spatial distributions of all species, apart from buffalo, were driven primarily by environmental factors, with limited responses to direct predation risk. Responses to predation risk were instead indirect, with species distributions driven by environmental factors, and diel patterns being particularly pronounced. Grazers were more responsive to the measured variables than browsers, with more observations in open areas. Terrain ruggedness was a stronger predictor of browser distributions than was vegetation density. Buffalo was the only species to respond to predator encounter risk, avoiding areas with higher lion utilization. Buffalo therefore behaved in similar ways to when lions were absent from the study area. Our results suggest that direct predation risk effects are relatively weak when predator densities are low and the time since reintroduction is short and emphasize the need for robust, long‐term monitoring of predator reintroductions to place such events in the broader context of predation risk effects.
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Affiliation(s)
- Andrew B Davies
- Department of Global Ecology Carnegie Institution for Science 260 Panama Street Stanford California 94305
| | - Craig J Tambling
- Department of Zoology Centre for African Conservation Ecology Nelson Mandela Metropolitan University Port Elizabeth 6031 South Africa
| | - Graham I H Kerley
- Department of Zoology Centre for African Conservation Ecology Nelson Mandela Metropolitan University Port Elizabeth 6031 South Africa
| | - Gregory P Asner
- Department of Global Ecology Carnegie Institution for Science 260 Panama Street Stanford California 94305
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Davies AB, Marneweck DG, Druce DJ, Asner GP. Den site selection, pack composition, and reproductive success in endangered African wild dogs. Behav Ecol 2016. [DOI: 10.1093/beheco/arw124] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Davies AB, Tambling CJ, Kerley GIH, Asner GP. Effects of Vegetation Structure on the Location of Lion Kill Sites in African Thicket. PLoS One 2016; 11:e0149098. [PMID: 26910832 PMCID: PMC4766088 DOI: 10.1371/journal.pone.0149098] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 01/27/2016] [Indexed: 11/18/2022] Open
Abstract
Predator-prey relationships are integral to ecosystem stability and functioning. These relationships are, however, difficult to maintain in protected areas where large predators are increasingly being reintroduced and confined. Where predators make kills has a profound influence on their role in ecosystems, but the relative importance of environmental variables in determining kill sites, and how these might vary across ecosystems is poorly known. We investigated kill sites for lions in South Africa’s thicket biome, testing the importance of vegetation structure for kill site locations compared to other environmental variables. Kill sites were located over four years using GPS telemetry and compared to non-kill sites that had been occupied by lions, as well as to random sites within lion ranges. Measurements of 3D vegetation structure obtained from Light Detection and Ranging (LiDAR) were used to calculate the visible area (viewshed) around each site and, along with wind and moonlight data, used to compare kill sites between lion sexes, prey species and prey sexes. Viewshed area was the most important predictor of kill sites (sites in dense vegetation were twice as likely to be kill sites compared to open areas), followed by wind speed and, less so, moonlight. Kill sites for different prey species varied with vegetation structure, and male prey were killed when wind speeds were higher compared to female prey of the same species. Our results demonstrate that vegetation structure is an important component of predator-prey interactions, with varying effects across ecosystems. Such differences require consideration in terms of the ecological roles performed by predators, and in predator and prey conservation.
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Affiliation(s)
- Andrew B. Davies
- Department of Global Ecology, Carnegie Institution for Science, 260 Panama Street, Stanford, California, 94305, United States of America
- * E-mail:
| | - Craig J. Tambling
- Centre for African Conservation Ecology, Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth, 6031, South Africa
| | - Graham I. H. Kerley
- Centre for African Conservation Ecology, Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth, 6031, South Africa
| | - Gregory P. Asner
- Department of Global Ecology, Carnegie Institution for Science, 260 Panama Street, Stanford, California, 94305, United States of America
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Dupuis-Desormeaux M, Davidson Z, Pratt L, Mwololo M, MacDonald SE. Testing the effects of perimeter fencing and elephant exclosures on lion predation patterns in a Kenyan wildlife conservancy. PeerJ 2016; 4:e1681. [PMID: 26893967 PMCID: PMC4756753 DOI: 10.7717/peerj.1681] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 01/21/2016] [Indexed: 11/20/2022] Open
Abstract
The use of fences to segregate wildlife can change predator and prey behaviour. Predators can learn to incorporate fencing into their hunting strategies and prey can learn to avoid foraging near fences. A twelve-strand electric predator-proof fence surrounds our study site. There are also porous one-strand electric fences used to create exclosures where elephant (and giraffe) cannot enter in order to protect blocs of browse vegetation for two critically endangered species, the black rhinoceros (Diceros bicornis) and the Grevy’s zebra (Equus grevyi). The denser vegetation in these exclosures attracts both browsing prey and ambush predators. In this study we examined if lion predation patterns differed near the perimeter fencing and inside the elephant exclosures by mapping the location of kills. We used a spatial analysis to compare the predation patterns near the perimeter fencing and inside the exclosures to predation in the rest of the conservancy. Predation was not over-represented near the perimeter fence but the pattern of predation near the fence suggests that fences may be a contributing factor to predation success. Overall, we found that predation was over-represented inside and within 50 m of the exclosures. However, by examining individual exclosures in greater detail using a hot spot analysis, we found that only a few exclosures contained lion predation hot spots. Although some exclosures provide good hunting grounds for lions, we concluded that exclosures did not necessarily create prey-traps per se and that managers could continue to use this type of exclusionary fencing to protect stands of dense vegetation.
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Affiliation(s)
| | - Zeke Davidson
- Conservation Department, Marwell Wildlife , Winchester, Hampshire , United Kingdom
| | - Laura Pratt
- Conservation Department, Marwell Wildlife , Winchester, Hampshire , United Kingdom
| | - Mary Mwololo
- Research Depeartment, Lewa Wildlife Conservancy , Isiolo , Kenya
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Abstract
Large mammalian terrestrial herbivores, such as elephants, have dramatic effects on the ecosystems they inhabit and at high population densities their environmental impacts can be devastating. Pleistocene terrestrial ecosystems included a much greater diversity of megaherbivores (e.g., mammoths, mastodons, giant ground sloths) and thus a greater potential for widespread habitat degradation if population sizes were not limited. Nevertheless, based on modern observations, it is generally believed that populations of megaherbivores (>800 kg) are largely immune to the effects of predation and this perception has been extended into the Pleistocene. However, as shown here, the species richness of big carnivores was greater in the Pleistocene and many of them were significantly larger than their modern counterparts. Fossil evidence suggests that interspecific competition among carnivores was relatively intense and reveals that some individuals specialized in consuming megaherbivores. To estimate the potential impact of Pleistocene large carnivores, we use both historic and modern data on predator-prey body mass relationships to predict size ranges of their typical and maximum prey when hunting as individuals and in groups. These prey size ranges are then compared with estimates of juvenile and subadult proboscidean body sizes derived from extant elephant growth data. Young proboscideans at their most vulnerable age fall within the predicted prey size ranges of many of the Pleistocene carnivores. Predation on juveniles can have a greater impact on megaherbivores because of their long interbirth intervals, and consequently, we argue that Pleistocene carnivores had the capacity to, and likely did, limit megaherbivore population sizes.
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Davies AB, Asner GP. Advances in animal ecology from 3D-LiDAR ecosystem mapping. Trends Ecol Evol 2015; 29:681-91. [PMID: 25457158 DOI: 10.1016/j.tree.2014.10.005] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 10/02/2014] [Accepted: 10/15/2014] [Indexed: 11/16/2022]
Abstract
The advent and recent advances of Light Detection and Ranging (LiDAR) have enabled accurate measurement of 3D ecosystem structure. Here, we review insights gained through the application of LiDAR to animal ecology studies, revealing the fundamental importance of structure for animals. Structural heterogeneity is most conducive to increased animal richness and abundance, and increased complexity of vertical vegetation structure is more positively influential compared with traditionally measured canopy cover, which produces mixed results. However, different taxonomic groups interact with a variety of 3D canopy traits and some groups with 3D topography. To develop a better understanding of animal dynamics, future studies will benefit from considering 3D habitat effects in a wider variety of ecosystems and with more taxa.
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Affiliation(s)
- Andrew B Davies
- Department of Global Ecology, Carnegie Institution for Science, 260 Panama Street, Stanford, CA 94305, USA.
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20
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Ripple WJ, Newsome TM, Wolf C, Dirzo R, Everatt KT, Galetti M, Hayward MW, Kerley GIH, Levi T, Lindsey PA, Macdonald DW, Malhi Y, Painter LE, Sandom CJ, Terborgh J, Van Valkenburgh B. Collapse of the world's largest herbivores. SCIENCE ADVANCES 2015; 1:e1400103. [PMID: 26601172 PMCID: PMC4640652 DOI: 10.1126/sciadv.1400103] [Citation(s) in RCA: 438] [Impact Index Per Article: 48.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 04/03/2015] [Indexed: 05/15/2023]
Abstract
Large wild herbivores are crucial to ecosystems and human societies. We highlight the 74 largest terrestrial herbivore species on Earth (body mass ≥100 kg), the threats they face, their important and often overlooked ecosystem effects, and the conservation efforts needed to save them and their predators from extinction. Large herbivores are generally facing dramatic population declines and range contractions, such that ~60% are threatened with extinction. Nearly all threatened species are in developing countries, where major threats include hunting, land-use change, and resource depression by livestock. Loss of large herbivores can have cascading effects on other species including large carnivores, scavengers, mesoherbivores, small mammals, and ecological processes involving vegetation, hydrology, nutrient cycling, and fire regimes. The rate of large herbivore decline suggests that ever-larger swaths of the world will soon lack many of the vital ecological services these animals provide, resulting in enormous ecological and social costs.
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Affiliation(s)
- William J. Ripple
- Trophic Cascades Program, Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331, USA
- Corresponding author. E-mail:
| | - Thomas M. Newsome
- Trophic Cascades Program, Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331, USA
- Desert Ecology Research Group, School of Biological Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Christopher Wolf
- Trophic Cascades Program, Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331, USA
| | - Rodolfo Dirzo
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Kristoffer T. Everatt
- Centre for African Conservation Ecology, Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth 6031, South Africa
| | - Mauro Galetti
- Departamento de Ecologia, Universidade Estadual Paulista (UNESP), C.P. 199, Rio Claro, São Paulo 13506-900, Brazil
| | - Matt W. Hayward
- Centre for African Conservation Ecology, Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth 6031, South Africa
- College of Natural Sciences, Bangor University, Thoday Building, Deiniol Road, Bangor, Gwynedd LL572UW, UK
| | - Graham I. H. Kerley
- Centre for African Conservation Ecology, Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth 6031, South Africa
| | - Taal Levi
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331, USA
| | - Peter A. Lindsey
- Lion Program, Panthera, 8 West 40th Street, 18th Floor, New York, NY 10018, USA
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, Gauteng 0001, South Africa
| | - David W. Macdonald
- Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Recanati-Kaplan Centre, Tubney House, Tubney, Abingdon OX13 5QL, UK
| | - Yadvinder Malhi
- Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK
| | - Luke E. Painter
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331, USA
| | - Christopher J. Sandom
- Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Recanati-Kaplan Centre, Tubney House, Tubney, Abingdon OX13 5QL, UK
| | - John Terborgh
- Nicholas School of the Environment and Earth Sciences, Duke University, P. O. Box 90381, Durham, NC 27708, USA
| | - Blaire Van Valkenburgh
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA 90095–7239, USA
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