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Benson JF, Dougherty KD, Beier P, Boyce WM, Cristescu B, Gammons DJ, Garcelon DK, Higley JM, Martins QE, Nisi AC, Riley SPD, Sikich JA, Stephenson TR, Vickers TW, Wengert GM, Wilmers CC, Wittmer HU, Dellinger JA. The ecology of human-caused mortality for a protected large carnivore. Proc Natl Acad Sci U S A 2023; 120:e2220030120. [PMID: 36940341 PMCID: PMC10068828 DOI: 10.1073/pnas.2220030120] [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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 02/15/2023] [Indexed: 03/22/2023] Open
Abstract
Mitigating human-caused mortality for large carnivores is a pressing global challenge for wildlife conservation. However, mortality is almost exclusively studied at local (within-population) scales creating a mismatch between our understanding of risk and the spatial extent most relevant to conservation and management of wide-ranging species. Here, we quantified mortality for 590 radio-collared mountain lions statewide across their distribution in California to identify drivers of human-caused mortality and investigate whether human-caused mortality is additive or compensatory. Human-caused mortality, primarily from conflict management and vehicles, exceeded natural mortality despite mountain lions being protected from hunting. Our data indicate that human-caused mortality is additive to natural mortality as population-level survival decreased as a function of increasing human-caused mortality and natural mortality did not decrease with increased human-caused mortality. Mortality risk increased for mountain lions closer to rural development and decreased in areas with higher proportions of citizens voting to support environmental initiatives. Thus, the presence of human infrastructure and variation in the mindset of humans sharing landscapes with mountain lions appear to be primary drivers of risk. We show that human-caused mortality can reduce population-level survival of large carnivores across large spatial scales, even when they are protected from hunting.
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Affiliation(s)
- John F. Benson
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE68583
| | - Kyle D. Dougherty
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE68583
| | - Paul Beier
- Center for Large Landscape Conservation, Bozeman, MT59715
| | - Walter M. Boyce
- Karen C. Drayer Wildlife Health Center, School of Veterinary Medicine, University of California, Davis, CA95616
| | - Bogdan Cristescu
- Environmental Studies Department, University of California, Santa Cruz, CA95064
| | | | | | | | | | - Anna C. Nisi
- Environmental Studies Department, University of California, Santa Cruz, CA95064
| | - Seth P. D. Riley
- National Park Service, Santa Monica Mountains National Recreation Area, Thousand Oaks, CA91360
| | - Jeff A. Sikich
- National Park Service, Santa Monica Mountains National Recreation Area, Thousand Oaks, CA91360
| | | | - T. Winston Vickers
- Karen C. Drayer Wildlife Health Center, School of Veterinary Medicine, University of California, Davis, CA95616
| | | | | | - Heiko U. Wittmer
- School of Biological Sciences, Victoria University of Wellington, Wellington6140, New Zealand
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Abstract
Demographic compensation, the increase in average individual performance following a perturbation that reduces population size, and, its opposite, demographic overadditivity (or superadditivity) are central processes in both population ecology and wildlife management. A continuum of population responses to changes in cause-specific mortality exists, of which additivity and complete compensation constitute particular points. The position of a population on that continuum influences its ability to sustain exploitation and predation. Here I describe a method for quantifying where a population is on the continuum. Based on variance-covariance formulae, I describe a simple metric for the rate of compensation-additivity. I synthesize the results from 10 wildlife capture-recapture monitoring programmes from the literature and online databases, reviewing current statistical methods and the treatment of common sources of bias. These results are used to test hypotheses regarding the effects of life-history strategy, population density, average cause-specific mortality and age class on the rate of compensation-additivity. This comparative analysis highlights that long-lived species compensate less than short-lived species and that populations below their carrying capacity compensate less than those above.
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Affiliation(s)
- Guillaume Péron
- Department of Wildland Resources, Utah State University, Logan, UT, 84322-5230, USA; Patuxent Wildlife Research Center, U.S. Geological Survey, 12100 Beech Forest Road, Laurel, MD, 20708-4017, USA; USGS Colorado Cooperative Fish and Wildlife Research Unit, Colorado State University, 1484 Campus Delivery, Fort Collins, CO, 80523-1484, USA
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