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Leighton GRM, Brooke AR, Froneman PW, Serieys LEK, Bishop JM. The Cat's Whiskers: Stable Isotopes Reveal Individual Specialisation of Adaptable Caracals ( Caracal caracal) Foraging in an Urbanising Landscape. Ecol Evol 2025; 15:e71154. [PMID: 40130006 PMCID: PMC11930547 DOI: 10.1002/ece3.71154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2024] [Revised: 02/12/2025] [Accepted: 03/07/2025] [Indexed: 03/26/2025] Open
Abstract
Urbanisation critically alters the availability of resources and the nature of risks for wildlife by fragmenting natural habitats and disrupting ecosystems. Despite these challenges, carnivores frequently persist in and around urban environments, where novel opportunities, such as anthropogenic food, may outweigh associated ecological risks. Here, we investigate the responses of an urban adapter to novel resources, using stable isotope analysis of vibrissae (whiskers) to understand the spatiotemporal foraging patterns of caracals (Caracal caracal) on the fringes of the city of Cape Town, South Africa. Caracals are medium-sized felids and the largest remaining predators on the Cape Peninsula. Using isotopic niche metrics and home range estimates, we assess the effects of demographics, seasonality, and urbanisation on variation in individual foraging behaviour from GPS-collar monitored caracals (n = 28) across an urban gradient. Despite a wide isotopic niche at the population level, we observed high levels of individual specialisation. Adult and male niches were wider, likely due to larger home ranges, which facilitate the exploitation of diverse prey across trophic levels. Patterns in δ 13C were seasonal, with increases during the warmer, drier summer months across the Peninsula irrespective of habitat use. Taken together with niche contraction for caracals in urban areas, our findings suggest higher reliance on human-subsidised resources in summer. Caracals using areas dominated by wildland cover had higher δ 15N values and larger niches than those using urban-dominated areas. Across the study area, δ 15N values varied spatially, with increased enrichment in caracals using more coastal and wetland areas and prey, particularly in winter. Individual foraging flexibility in caracal is clearly a key strategy for their success in this rapidly transforming landscape. Understanding spatiotemporal shifts in dietary niche and trophic ecology in adaptable urban carnivores, like the Cape Peninsula caracals, is fundamental for understanding the ecological needs of wildlife in and around rapidly growing cities.
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Affiliation(s)
- Gabriella R. M. Leighton
- Institute for Communities and Wildlife in Africa, Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
| | - Anna R. Brooke
- Institute for Communities and Wildlife in Africa, Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
| | - P. William Froneman
- Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
| | - Laurel E. K. Serieys
- Institute for Communities and Wildlife in Africa, Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
- Cape Leopard TrustCape TownSouth Africa
| | - Jacqueline M. Bishop
- Institute for Communities and Wildlife in Africa, Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
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Ram AK, Lamichhane BR, Subedi N, Yadav NK, Karki A, Pandav B, Brown C, Khatri TB, Yackulic CB. Dynamic occupancy modelling of Asian elephants (Elephas maximus) reveals increasing landscape use in Nepal. Sci Rep 2024; 14:20023. [PMID: 39198461 PMCID: PMC11358544 DOI: 10.1038/s41598-024-70092-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 08/13/2024] [Indexed: 09/01/2024] Open
Abstract
Large mammals with general habitat needs can persist throughout mixed used landscapes, however, human-wildlife conflict frequently leads to their restriction to protected areas. Conservation efforts, especially for reducing conflicts with humans, can enhance tolerance of humans towards species like Asian elephants (Elephas maximus) in human-dominated landscapes. Here, we examine how elephant use in the Chure Terai Madhesh Landscape (CTML) covering the entire elephant range of Nepal changed between 2012 and 2020 in relationship to protection status and environmental conditions. We systematically surveyed ~ 42,000 km2 of potential habitat, by dividing the study area into 159 grid cells of 15 × 15 km2 and recorded elephant signs during the cool, dry season in three years (2012, 2018 and 2020). We analyzed the survey data in a single-species, multi-season (dynamic) occupancy modeling framework to test hypotheses regarding the influence of environmental conditions and protected area status on landscape use by elephants over time. The best-supported model included protected area effects on initial use, colonization, and detection probability as well as temporal variation in colonization and detection probability. Initial use and colonization rates were higher in protected areas, however elephants increasingly used cells located both inside and outside the protected areas, and the difference in use between protected areas and outside declined as elephants use became prevalent across most of the landscape. While elephant use was patchily distributed in the first year of surveys consistent with past descriptions of four sub-populations, elephant use consolidated into a western and eastern region in subsequent years with a gap in their distribution occurring between Chitwan and Bardiya National Parks. Our manuscript highlights the increasing landscape use by elephants in both protected areas and areas outside protected areas and suggests that management interventions that focus on reducing conflicts can promote greater use of both protected areas and areas outside of protected areas.
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Affiliation(s)
- Ashok Kumar Ram
- Department of National Parks and Wildlife Conservation, Babarmahal, Kathmandu, Nepal.
- Wildlife Institute of India, Dehradun, India.
| | - Babu Ram Lamichhane
- National Trust for Nature Conservation, Khumaltar, Lalitpur, Nepal
- USAID Biodiversity (Jal Jangal), Sanepa, Lalitpur, Nepal
| | - Naresh Subedi
- National Trust for Nature Conservation, Khumaltar, Lalitpur, Nepal
| | - Nabin Kumar Yadav
- Ministry of Forests and Environment, Madhesh Pradesh, Janakpur, Nepal
| | - Ajay Karki
- Department of National Parks and Wildlife Conservation, Babarmahal, Kathmandu, Nepal
- Department of Zoology and Physiology, Haub School of Environment and Natural Resources, University of Wyoming, Laramie, WY, USA
| | | | - Cory Brown
- US Fish and Wildlife Service, Washington, DC, USA
| | - Top B Khatri
- Ecosystem Based Adaptation Program (EBA) II, Kathmandu, Nepal
| | - Charles B Yackulic
- Southwest Biological Science Center, U.S. Geological Survey, Flagstaff, AZ, USA.
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Mohan M, Sathyakumar S, Krishnamurthy R. Predator in proximity: how does a large carnivore respond to anthropogenic pressures at fine-scales? Implications for interface area management. PeerJ 2024; 12:e17693. [PMID: 39006024 PMCID: PMC11246029 DOI: 10.7717/peerj.17693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 06/14/2024] [Indexed: 07/16/2024] Open
Abstract
Background Driven by habitat loss and fragmentation, large carnivores are increasingly navigating human-dominated landscapes, where their activity is restricted and their behaviour altered. This movement, however, raises significant concerns and costs for people living nearby. While intricately linked, studies often isolate human and carnivore impacts, hindering effective management efforts. Hence, in this study, we brought these two into a common framework, focusing on an interface area between the critical tiger habitat and the human-dominated multiple-use buffer area of a central Indian protected area. Methods We employed a fine-scale camera trap survey complemented by GPS-collar movement data to understand spatio-temporal activity patterns and adjustments of tigers in response to anthropogenic pressures. We used an occupancy framework to evaluate space use, Bayesian circular GLMs to model temporal activity, and home range and step length analyses to assess the movement patterns of tigers. Further, we used predation-risk models to understand conflict patterns as a function of tiger presence and other habitat variables. Results Despite disturbance, a high proportion of the sampled area was occupied by 17 unique tigers (ψ = 0.76; CI [0.73-0.92]). The distance to villages (β ± SE = 0.63 ± 0.21) and the relative abundance of large-bodied wild prey (β ± SE = 0.72 ± 0.37) emerged as key predictors of tiger space use probability, indicating a preference for wild prey by tigers, while human influences constrained their habitat utilisation. Distance to villages was also identified as the most significant predictor of the tigers' temporal activity (μ ± σ = 3.03 ± 0.06 rad) that exhibited higher nocturnality near villages. A total of 11% of tiger home ranges were within village boundaries, accompanied by faster movement in these areas (displacement 40-82% higher). Livestock depredation probability by tigers increased with proximity to villages (P = 0.002) and highway (P = 0.003). Although tiger space use probability (P = 0.056) and wild prey abundance (P = 0.134) were non-significant at the 0.05 threshold, their presence in the best-fit predation-risk model suggests their contextual relevance for understanding conflict risk. The results highlight the importance of appropriately managing livestock near human infrastructures to effectively mitigate conflict. Conclusions Shared space of carnivores and humans requires dynamic site-specific actions grounded in evidence-based decision-making. This study emphasises the importance of concurrently addressing the intricate interactions between humans and large carnivores, particularly the latter's behavioural adaptations and role in conflict dynamics. Such an integrated approach is essential to unravel cause-effect relationships and promote effective interface management in human-dominated landscapes.
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Affiliation(s)
- Manu Mohan
- Post-Graduate Programme in Wildlife Science, Wildlife Institute of India, Dehradun, Uttarakhand, India
- Department of Landscape Level Planning and Management, Wildlife Institute of India, Dehradun, Uttarakhand, India
| | - Sambandam Sathyakumar
- Department of Endangered Species Management, Wildlife Institute of India, Dehradun, Uttarakhand, India
| | - Ramesh Krishnamurthy
- Department of Landscape Level Planning and Management, Wildlife Institute of India, Dehradun, Uttarakhand, India
- Faculty of Forestry, University of British Columbia, Vancouver, British Columbia, Canada
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Kyriazis CC, Serieys LE, Bishop JM, Drouilly M, Viljoen S, Wayne RK, Lohmueller KE. The influence of gene flow on population viability in an isolated urban caracal population. Mol Ecol 2024; 33:e17346. [PMID: 38581173 PMCID: PMC11035096 DOI: 10.1111/mec.17346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 01/23/2024] [Accepted: 03/26/2024] [Indexed: 04/08/2024]
Abstract
Wildlife populations are becoming increasingly fragmented by anthropogenic development. Small and isolated populations often face an elevated risk of extinction, in part due to inbreeding depression. Here, we examine the genomic consequences of urbanization in a caracal (Caracal caracal) population that has become isolated in the Cape Peninsula region of the City of Cape Town, South Africa, and is thought to number ~50 individuals. We document low levels of migration into the population over the past ~75 years, with an estimated rate of 1.3 effective migrants per generation. As a consequence of this isolation and small population size, levels of inbreeding are elevated in the contemporary Cape Peninsula population (mean FROH = 0.20). Inbreeding primarily manifests as long runs of homozygosity >10 Mb, consistent with the effects of isolation due to the rapid recent growth of Cape Town. To explore how reduced migration and elevated inbreeding may impact future population dynamics, we parameterized an eco-evolutionary simulation model. We find that if migration rates do not change in the future, the population is expected to decline, though with a low projected risk of extinction. However, if migration rates decline or anthropogenic mortality rates increase, the potential risk of extinction is greatly elevated. To avert a population decline, we suggest that translocating migrants into the Cape Peninsula to initiate a genetic rescue may be warranted in the near future. Our analysis highlights the utility of genomic datasets coupled with computational simulation models for investigating the influence of gene flow on population viability.
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Affiliation(s)
- Christopher C. Kyriazis
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA
| | - Laurel E.K. Serieys
- Panthera, 8 W 40th St, 18th Floor, New York, NY 10018, USA
- Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, 7701, South Africa
| | - Jacqueline M. Bishop
- Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, 7701, South Africa
| | - Marine Drouilly
- Panthera, 8 W 40th St, 18th Floor, New York, NY 10018, USA
- Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, 7701, South Africa
- Centre for Social Science Research, University of Cape Town, Rondebosch, 7701, South Africa
| | - Storme Viljoen
- Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, 7701, South Africa
| | - Robert K. Wayne
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA
| | - Kirk E. Lohmueller
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA
- Interdepartmental Program in Bioinformatics, University of California, Los Angeles, CA 90095, USA
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Luther DA, Wolfe JD, Johnson E, Stouffer PC, Batchelor J, Tarwater CE. Habitat use of Amazonian birds varies by age and foraging guild along a disturbance gradient. Proc Biol Sci 2024; 291:20240866. [PMID: 38808444 PMCID: PMC11285749 DOI: 10.1098/rspb.2024.0866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2024] [Accepted: 05/02/2024] [Indexed: 05/30/2024] Open
Abstract
Patterns of habitat use directly influence a species' fitness, yet for many species an individual's age can influence patterns of habitat use. However, in tropical rainforests, which host the greatest terrestrial species diversity, little is known about how age classes of different species use different adjacent habitats of varying quality. We use long-term mist net data from the Amazon rainforest to assess patterns of habitat use among adult, adolescent (teenage) and young understory birds in forest fragments, primary and secondary forest at the Biological Dynamics of Forest Fragments Project in Brazil. Insectivore adults were most common in primary forest, adolescents were equally likely in primary and secondary forest, and all ages were the least common in forest fragments. In contrast to insectivores, frugivores and omnivores showed no differences among all three habitat types. Our results illustrate potential ideal despotic distributions among breeding populations of some guilds of understory birds where adult insectivores may competitively exclude adolescent individuals from primary forest. Secondary forest recovery appears to hold promise as a breeding habitat for frugivore and omnivore species but only as a pre-breeding habitat for insectivores, but as the forest ages, the demographic structure of bird populations should match that of primary forest.
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Affiliation(s)
- David A. Luther
- Biology Department, George Mason University, 4400 University Dr, Fairfax, VA, 22030, USA
| | - Jared D. Wolfe
- College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI, USA
| | | | - Philip C. Stouffer
- School of Renewable Natural Resources, Louisiana State University and Biological Dynamics of Forest Fragments Project, Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus, Amazonas, Brazil
| | - Jacquelyn Batchelor
- Biology Department, George Mason University, 4400 University Dr, Fairfax, VA, 22030, USA
| | - Corey E. Tarwater
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
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Leighton GRM, Froneman PW, Serieys LEK, Bishop JM. Sustained use of marine subsidies promotes niche expansion in a wild felid. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 914:169912. [PMID: 38184259 DOI: 10.1016/j.scitotenv.2024.169912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/18/2023] [Accepted: 01/02/2024] [Indexed: 01/08/2024]
Abstract
The use of marine subsidies by terrestrial predators can facilitate substantial transfer of nutrients between marine and terrestrial ecosystems. Marine resource subsidies may have profound effects on predator ecology, influencing population and niche dynamics. Expanding niches of top consumers can impact ecosystem resilience and interspecific interactions, affecting predator-prey dynamics and competition. We investigate the occurrence, importance, and impact of marine resources on trophic ecology and niche dynamics in a highly generalist predator, the caracal (Caracal caracal), on the Cape Peninsula, South Africa. Caracals have flexible diets, feeding across a wide range of terrestrial and aquatic prey. We use carbon and nitrogen stable isotope analysis of fur samples (n = 75) to understand trophic position and niche shifts in coastal and inland foragers, as well as the implications of a diet rich in marine resources. We found significant differences in isotope signatures between these groups, with higher δ13C (P < 0.05) and δ15N values (P < 0.01) in coastal foragers. Isotope mixing models reveal that these elevated signatures were due to non-terrestrial food subsidies, where approximately a third of coastal foraging caracal diet comprised marine prey. The addition of marine prey species to diet increased both the trophic level and isotope niche size of coastal foraging caracals, with potential impacts on prey populations and competition. Our results suggest that marine prey are an important dietary resource for coastal foraging caracals, where seabirds, including two endangered species, are a major component of their diet. However, there are likely risks associated with these resource benefits, as routine consumption of seabirds is linked with higher pollutant burdens, particularly metals. Increased encounters between this terrestrial predator and seabirds may be a result of increased mainland colonies due to changes in habitat availability and the highly opportunistic and generalist foraging behaviour of a native predator.
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Affiliation(s)
- Gabriella R M Leighton
- Department of Zoology and Entomology, Rhodes University, PO Box 94, Grahamstown 6140, South Africa; Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, Cape Town 7701, South Africa.
| | - P William Froneman
- Department of Zoology and Entomology, Rhodes University, PO Box 94, Grahamstown 6140, South Africa
| | - Laurel E K Serieys
- Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, Cape Town 7701, South Africa; Panthera, NY, New York, USA; Cape Leopard Trust, Cape Town, South Africa
| | - Jacqueline M Bishop
- Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, Cape Town 7701, South Africa
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