The role of environmental, structural and anthropogenic variables on underpass use by African savanna elephants (Loxodonta africana) in the Tsavo Conservation Area
Wildlife crossing structures are effective interventions for mitigating fragmentation of habitats by linear infrastructure. The 2017 construction of a new railway cutting through the Tsavo Conservation Area (TCA), home to the largest elephant population in Kenya, affected wildlife movement and habit...
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| Format: | Article |
| Language: | English |
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Elsevier
2022-10-01
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| Series: | Global Ecology and Conservation |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2351989422002013 |
| _version_ | 1811235980302090240 |
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| author | Michael Koskei Joseph Kolowski George Wittemyer Fredrick Lala Iain Douglas-Hamilton Benson Okita-Ouma |
| author_facet | Michael Koskei Joseph Kolowski George Wittemyer Fredrick Lala Iain Douglas-Hamilton Benson Okita-Ouma |
| author_sort | Michael Koskei |
| collection | DOAJ |
| description | Wildlife crossing structures are effective interventions for mitigating fragmentation of habitats by linear infrastructure. The 2017 construction of a new railway cutting through the Tsavo Conservation Area (TCA), home to the largest elephant population in Kenya, affected wildlife movement and habitat connectivity. Although numerous studies have investigated the use of wildlife crossing structures by a wide range of species, few have focused on their use by megaherbivores. In this study, we examined use of 41 wildlife crossing structures by African savanna elephants (Loxodonta africana) along a 133 km section of new railway in Tsavo, Kenya. We used a generalized linear mixed modeling approach to assess the relationship between elephant crossing rate over 28 months between July 2017 to April 2021 and explanatory factors including crossing structure attributes, livestock presence and proximity to highways, water points and human settlement. We found that structural attributes of crossing structures were most strongly associated with the elephant crossing rate, particularly height and its interaction with type of crossing structure (bridges, wildlife underpasses and culverts). Higher crossing structures were associated with higher crossing rate, with the largest influence of height at culverts and wildlife underpasses. Although bridges comprised only 19.5 % of the 41 available crossing structures, they accounted for a disproportionately high number of elephants crossing events (56 %). The results demonstrated the importance of bridges over designated crossing structures for elephants, with predicted seasonal counts of elephant crossings being 0.31 for average sized culverts, 2.88 for wildlife underpasses and 5.86 for bridges. The environmental and anthropogenic variables were not strongly associated with elephant crossing rate. Our findings have direct application for future siting, and design of crossing structures across elephant ranges. |
| first_indexed | 2024-04-12T12:01:25Z |
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| id | doaj.art-7e745a8579c54f45938b13a5b3e0ca41 |
| institution | Directory Open Access Journal |
| issn | 2351-9894 |
| language | English |
| last_indexed | 2024-04-12T12:01:25Z |
| publishDate | 2022-10-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Global Ecology and Conservation |
| spelling | doaj.art-7e745a8579c54f45938b13a5b3e0ca412022-12-22T03:33:50ZengElsevierGlobal Ecology and Conservation2351-98942022-10-0138e02199The role of environmental, structural and anthropogenic variables on underpass use by African savanna elephants (Loxodonta africana) in the Tsavo Conservation AreaMichael Koskei0Joseph Kolowski1George Wittemyer2Fredrick Lala3Iain Douglas-Hamilton4Benson Okita-Ouma5Save The Elephants, P.O. Box 54667, Nairobi 00200, Kenya; Corresponding author.Smithsonian-Mason School of Conservation, Smithsonian Conservation Biology Institute, Front Royal, VA, USASave The Elephants, P.O. Box 54667, Nairobi 00200, Kenya; Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO 80523, USAWildlife Research and Training Institute, P.O. Box 842-20117, Naivasha, KenyaSave The Elephants, P.O. Box 54667, Nairobi 00200, Kenya; Department of Zoology, Oxford University, Oxford, UKSave The Elephants, P.O. Box 54667, Nairobi 00200, Kenya; Wyss Academy for Nature at the University of Bern; Kochergasse 4, 3011 Bern, SwitzerlandWildlife crossing structures are effective interventions for mitigating fragmentation of habitats by linear infrastructure. The 2017 construction of a new railway cutting through the Tsavo Conservation Area (TCA), home to the largest elephant population in Kenya, affected wildlife movement and habitat connectivity. Although numerous studies have investigated the use of wildlife crossing structures by a wide range of species, few have focused on their use by megaherbivores. In this study, we examined use of 41 wildlife crossing structures by African savanna elephants (Loxodonta africana) along a 133 km section of new railway in Tsavo, Kenya. We used a generalized linear mixed modeling approach to assess the relationship between elephant crossing rate over 28 months between July 2017 to April 2021 and explanatory factors including crossing structure attributes, livestock presence and proximity to highways, water points and human settlement. We found that structural attributes of crossing structures were most strongly associated with the elephant crossing rate, particularly height and its interaction with type of crossing structure (bridges, wildlife underpasses and culverts). Higher crossing structures were associated with higher crossing rate, with the largest influence of height at culverts and wildlife underpasses. Although bridges comprised only 19.5 % of the 41 available crossing structures, they accounted for a disproportionately high number of elephants crossing events (56 %). The results demonstrated the importance of bridges over designated crossing structures for elephants, with predicted seasonal counts of elephant crossings being 0.31 for average sized culverts, 2.88 for wildlife underpasses and 5.86 for bridges. The environmental and anthropogenic variables were not strongly associated with elephant crossing rate. Our findings have direct application for future siting, and design of crossing structures across elephant ranges.http://www.sciencedirect.com/science/article/pii/S2351989422002013African elephantRailwayTsavoUnderpassWildlife crossing structureWildlife movement |
| spellingShingle | Michael Koskei Joseph Kolowski George Wittemyer Fredrick Lala Iain Douglas-Hamilton Benson Okita-Ouma The role of environmental, structural and anthropogenic variables on underpass use by African savanna elephants (Loxodonta africana) in the Tsavo Conservation Area Global Ecology and Conservation African elephant Railway Tsavo Underpass Wildlife crossing structure Wildlife movement |
| title | The role of environmental, structural and anthropogenic variables on underpass use by African savanna elephants (Loxodonta africana) in the Tsavo Conservation Area |
| title_full | The role of environmental, structural and anthropogenic variables on underpass use by African savanna elephants (Loxodonta africana) in the Tsavo Conservation Area |
| title_fullStr | The role of environmental, structural and anthropogenic variables on underpass use by African savanna elephants (Loxodonta africana) in the Tsavo Conservation Area |
| title_full_unstemmed | The role of environmental, structural and anthropogenic variables on underpass use by African savanna elephants (Loxodonta africana) in the Tsavo Conservation Area |
| title_short | The role of environmental, structural and anthropogenic variables on underpass use by African savanna elephants (Loxodonta africana) in the Tsavo Conservation Area |
| title_sort | role of environmental structural and anthropogenic variables on underpass use by african savanna elephants loxodonta africana in the tsavo conservation area |
| topic | African elephant Railway Tsavo Underpass Wildlife crossing structure Wildlife movement |
| url | http://www.sciencedirect.com/science/article/pii/S2351989422002013 |
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