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Santiago-Ávila FJ, Agan S, Hinton JW, Treves A. Evaluating how management policies affect red wolf mortality and disappearance. ROYAL SOCIETY OPEN SCIENCE 2022; 9:210400. [PMID: 35620012 PMCID: PMC9128856 DOI: 10.1098/rsos.210400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 04/27/2022] [Indexed: 05/06/2023]
Abstract
Poaching is the major cause of death for large carnivores in several regions, contributing to their global endangerment. The traditional hypothesis used in wildlife management (killing for tolerance) suggests reducing protections for a species will decrease poaching. However, recent studies suggest reducing protections will instead increase poaching (facilitated illegal killing) and its concealment (facilitated cryptic poaching). Here, we build survival and competing risk models for mortality and disappearances of adult collared red wolves (Canis rufus) released in North Carolina, USA from 1987 to 2020 (n = 526). We evaluated how changes in federal and state policies protecting red wolves influenced the hazard and incidence of mortality and disappearance. We observed substantial increases in the hazard and incidence of red wolf reported poaching, and smaller increases in disappearances, during periods of reduced federal and state protections (including liberalizing hunting of coyotes, C. latrans); white-tailed deer (Odocoileus virginianus) and American black bear (Ursus americanus) hunting seasons; and management phases. Observed increases in hazard (85-256%) and incidence of reported poaching (56-243%) support the 'facilitated illegal killing' hypothesis. We suggest improving protective policies intended to conserve endangered species generally and large carnivores in particular, to mitigate environmental crimes and generally improve the protection of wild animals.
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Affiliation(s)
- Francisco J. Santiago-Ávila
- Nelson Institute for Environmental Studies, University of Wisconsin, Madison, WI, USA
- Project Coyote, Larkspur, CA, USA
- The Rewilding Institute, Albuquerque, NM, USA
| | - Suzanne Agan
- Department of Ecology, Evolution, and Organismal Biology, Kennesaw State University, Kennesaw, GA, USA
| | | | - Adrian Treves
- Nelson Institute for Environmental Studies, University of Wisconsin, Madison, WI, USA
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2
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Santiago-Ávila FJ, Agan S, Hinton JW, Treves A. Evaluating how management policies affect red wolf mortality and disappearance. ROYAL SOCIETY OPEN SCIENCE 2022. [PMID: 35620012 DOI: 10.6084/m9.figshare.c.5980322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Poaching is the major cause of death for large carnivores in several regions, contributing to their global endangerment. The traditional hypothesis used in wildlife management (killing for tolerance) suggests reducing protections for a species will decrease poaching. However, recent studies suggest reducing protections will instead increase poaching (facilitated illegal killing) and its concealment (facilitated cryptic poaching). Here, we build survival and competing risk models for mortality and disappearances of adult collared red wolves (Canis rufus) released in North Carolina, USA from 1987 to 2020 (n = 526). We evaluated how changes in federal and state policies protecting red wolves influenced the hazard and incidence of mortality and disappearance. We observed substantial increases in the hazard and incidence of red wolf reported poaching, and smaller increases in disappearances, during periods of reduced federal and state protections (including liberalizing hunting of coyotes, C. latrans); white-tailed deer (Odocoileus virginianus) and American black bear (Ursus americanus) hunting seasons; and management phases. Observed increases in hazard (85-256%) and incidence of reported poaching (56-243%) support the 'facilitated illegal killing' hypothesis. We suggest improving protective policies intended to conserve endangered species generally and large carnivores in particular, to mitigate environmental crimes and generally improve the protection of wild animals.
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Affiliation(s)
- Francisco J Santiago-Ávila
- Nelson Institute for Environmental Studies, University of Wisconsin, Madison, WI, USA
- Project Coyote, Larkspur, CA, USA
- The Rewilding Institute, Albuquerque, NM, USA
| | - Suzanne Agan
- Department of Ecology, Evolution, and Organismal Biology, Kennesaw State University, Kennesaw, GA, USA
| | | | - Adrian Treves
- Nelson Institute for Environmental Studies, University of Wisconsin, Madison, WI, USA
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Santiago-Ávila FJ, Agan S, Hinton JW, Treves A. Evaluating how management policies affect red wolf mortality and disappearance. ROYAL SOCIETY OPEN SCIENCE 2022. [PMID: 35620012 DOI: 10.5061/dryad.8cz8w9gsr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Poaching is the major cause of death for large carnivores in several regions, contributing to their global endangerment. The traditional hypothesis used in wildlife management (killing for tolerance) suggests reducing protections for a species will decrease poaching. However, recent studies suggest reducing protections will instead increase poaching (facilitated illegal killing) and its concealment (facilitated cryptic poaching). Here, we build survival and competing risk models for mortality and disappearances of adult collared red wolves (Canis rufus) released in North Carolina, USA from 1987 to 2020 (n = 526). We evaluated how changes in federal and state policies protecting red wolves influenced the hazard and incidence of mortality and disappearance. We observed substantial increases in the hazard and incidence of red wolf reported poaching, and smaller increases in disappearances, during periods of reduced federal and state protections (including liberalizing hunting of coyotes, C. latrans); white-tailed deer (Odocoileus virginianus) and American black bear (Ursus americanus) hunting seasons; and management phases. Observed increases in hazard (85-256%) and incidence of reported poaching (56-243%) support the 'facilitated illegal killing' hypothesis. We suggest improving protective policies intended to conserve endangered species generally and large carnivores in particular, to mitigate environmental crimes and generally improve the protection of wild animals.
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Affiliation(s)
- Francisco J Santiago-Ávila
- Nelson Institute for Environmental Studies, University of Wisconsin, Madison, WI, USA
- Project Coyote, Larkspur, CA, USA
- The Rewilding Institute, Albuquerque, NM, USA
| | - Suzanne Agan
- Department of Ecology, Evolution, and Organismal Biology, Kennesaw State University, Kennesaw, GA, USA
| | | | - Adrian Treves
- Nelson Institute for Environmental Studies, University of Wisconsin, Madison, WI, USA
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Treves A, Louchouarn NX. Uncertainty and precaution in hunting wolves twice in a year. PLoS One 2022; 17:e0259604. [PMID: 35294446 PMCID: PMC8926205 DOI: 10.1371/journal.pone.0259604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 02/08/2022] [Indexed: 12/02/2022] Open
Abstract
When humanity confronts the risk of extinction of species, many people invoke precautions, especially in the face of uncertainty. Although precautionary approaches are value judgments, the optimal design and effect of precautions or lack thereof are scientific questions. We investigated Wisconsin gray wolves Canis lupus facing a second wolf-hunt in November 2021 and use three legal thresholds as the societal value judgments about precautions: (1) the 1999 population goal, 350 wolves, (2) the threshold for statutory listing under the state threatened and endangered species act, 250 wolves; and (3) state extirpation <2 wolves. This allows us to explore the quantitative relationship between precaution and uncertainty. Working from estimates of the size wolf population in April 2021 and reproduction to November, we constructed a simple linear model with uninformative priors for the period April 2021-April 2022 including an uncertain wolf-hunt in November 2021. Our first result is that the state government under-counted wolf deaths in the year preceding both wolf-hunts. We recommend better scientific analysis be used when setting wolf-hunt quotas. We find official recommendations for a quota for the November 2021 wolf-hunt risk undesirable outcomes. Even a quota of zero has a 13% chance of crossing threshold 1. Therefore, a zero death toll would be precautionary. Proponents for high quotas bear the burden of proof that their estimates are accurate, precise, and reproducible. We discuss why our approach is transferable to non-wolves. We show how scientists have the tools and concepts for quantifying and explaining the probabilities of crossing thresholds set by laws or other social norms. We recommend that scientists grapple with data gaps by explaining what the uncertainty means for policy and the public including the consequences of being wrong.
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Affiliation(s)
- Adrian Treves
- Nelson Institute for Environmental Studies, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Naomi X. Louchouarn
- Nelson Institute for Environmental Studies, University of Wisconsin, Madison, Wisconsin, United States of America
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Santiago-Ávila FJ, Treves A. Poaching of protected wolves fluctuated seasonally and with non-wolf hunting. Sci Rep 2022; 12:1738. [PMID: 35110599 PMCID: PMC8810790 DOI: 10.1038/s41598-022-05679-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 01/17/2022] [Indexed: 12/22/2022] Open
Abstract
Poaching is the main cause of mortality for many large carnivores, and mitigating it is imperative for the persistence of their populations. For Wisconsin gray wolves (Canis lupus), periods of increased risk in overall mortality and poaching seem to overlap temporally with legal hunting seasons for other large mammals (hunting wolves was prohibited). We analyzed monitoring data from adult, collared wolves in Wisconsin, USA (1979-2012, n = 495) using a competing-risk approach to test explicitly if seasons during which it was legal to train hunting hounds (hounding) or hunt other large mammals (hunting) affected wolves' hazard of cause-specific mortality and disappearance. We found increases in hazard for disappearances and documented ('reported') poaching during seasons with hunting, hounding or snow cover relative to a season without these factors. The 'reported poached' hazard increased > 650% during seasons with hunting and snow cover, which may be due to a seasonal surge in numbers of potential poachers or to some poachers augmenting their activities. Snow cover was a major environmental factor contributing to poaching, presumably through increased detection of wolves. Our study suggests poaching is by far the highest mortality hazard for wolves and reinforces the need for protections and policies targeting poaching of protected populations.
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Affiliation(s)
| | - Adrian Treves
- Nelson Institute for Environmental Studies, University of Wisconsin - Madison, Madison, USA
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Treves A, Santiago-Ávila FJ, Putrevu K. Quantifying the effects of delisting wolves after the first state began lethal management. PeerJ 2021; 9:e11666. [PMID: 34268009 PMCID: PMC8265384 DOI: 10.7717/peerj.11666] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 06/02/2021] [Indexed: 11/23/2022] Open
Abstract
Predators and their protection are controversial worldwide. Gray wolves, Canis lupus, lost U.S. federal protection (delisting) and the State of Wisconsin began lethal management first among all states and tribes that regained authority over wolves. Here we evaluated the initial success of reaching the state's explicit objective, "…to allow for a sustainable harvest that neither increases nor decreases the state's wolf population…" We used official state figures for hunter-killed wolves, population estimates from April 2017-2020, and the latest peer-reviewed model of individual wolf survival to estimate additional deaths resulting from federal delisting. More than half of the additional deaths were predicted to be cryptic poaching under the assumption that this period resembled past periods of liberalized wolf-killing in Wisconsin. We used a precautionary approach to construct three conservative scenarios to predict the current status of this wolf population and a minimum estimate of population decline since April 2020. From our scenarios that vary in growth rates and additional mortality estimates, we expect a maximum of 695-751 wolves to be alive in Wisconsin by 15 April 2021, a minimum 27-33% decline in the preceding 12 months. This contradicts the state expectation of no change in the population size. We draw a conclusion about the adequacy of regulatory mechanisms under state control of wolves and discuss the particular governance conditions met in Wisconsin. We recommend greater rigor and independent review of the science used by agencies to plan wolf hunting quotas and methods. We recommend clearer division of duties between state wildlife agencies, legislatures, and courts. We recommend federal governments reconsider the practice of sudden deregulation of wolf management and instead recommend they consider protecting predators as non-game or transition more slowly to subnational authority, to avoid the need for emergency relisting.
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Affiliation(s)
- Adrian Treves
- Nelson Institute for Environmental Studies, University of Wisconsin, Madison, Wisconsin, United States
| | | | - Karann Putrevu
- Nelson Institute for Environmental Studies, University of Wisconsin, Madison, Wisconsin, United States
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Louchouarn NX, Santiago-Ávila FJ, Parsons DR, Treves A. Evaluating how lethal management affects poaching of Mexican wolves. ROYAL SOCIETY OPEN SCIENCE 2021; 8:200330. [PMID: 33959305 PMCID: PMC8074884 DOI: 10.1098/rsos.200330] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 02/18/2021] [Indexed: 05/06/2023]
Abstract
Despite illegal killing (poaching) being the major cause of death among large carnivores globally, little is known about the effect of implementing lethal management policies on poaching. Two opposing hypotheses have been proposed in the literature: implementing lethal management may decrease poaching incidence (killing for tolerance) or increase it (facilitated illegal killing). Here, we report a test of the two opposed hypotheses that poaching (reported and unreported) of Mexican grey wolves (Canis lupus baileyi) in Arizona and New Mexico, USA, responded to changes in policy that reduced protections to allow more wolf-killing. We employ advanced biostatistical survival and competing risk methods to data on individual resightings, mortality and disappearances of collared Mexican wolves, supplemented with Bayes factors to assess the strength of evidence. We find inconclusive evidence for any decreases in reported poaching. We also find strong evidence that Mexican wolves were 121% more likely to disappear during periods of reduced protections than during periods of stricter protections, with only slight changes in legal removals by the agency. Therefore, we find strong support for the 'facilitated illegal killing' hypothesis and none for the 'killing for tolerance' hypothesis. We provide recommendations for improving the effectiveness of US policy on environmental crimes, endangered species and protections for wild animals. Our results have implications beyond the USA or wolves because the results suggest transformations of decades-old management interventions against human-caused mortality among wild animals subject to high rates of poaching.
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Affiliation(s)
- Naomi X. Louchouarn
- Nelson Institute for Environmental Studies, University of Wisconsin-Madison, Madison, WI, USA
| | - Francisco J. Santiago-Ávila
- Nelson Institute for Environmental Studies, University of Wisconsin-Madison, Madison, WI, USA
- Project Coyote Science Advisory Board, Larkspur, CA, USA
| | | | - Adrian Treves
- Nelson Institute for Environmental Studies, University of Wisconsin-Madison, Madison, WI, USA
- Project Coyote Science Advisory Board, Larkspur, CA, USA
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Liberalizing the killing of endangered wolves was associated with more disappearances of collared individuals in Wisconsin, USA. Sci Rep 2020; 10:13881. [PMID: 32807840 PMCID: PMC7431570 DOI: 10.1038/s41598-020-70837-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 08/04/2020] [Indexed: 11/22/2022] Open
Abstract
Although poaching (illegal killing) is an important cause of death for large carnivores globally, the effect of lethal management policies on poaching is unknown for many populations. Two opposing hypotheses have been proposed: liberalizing killing may decrease poaching incidence (‘tolerance hunting’) or increase it (‘facilitated poaching’). For gray wolves in Wisconsin, USA, we evaluated how five causes of death and disappearances of monitored, adult wolves were influenced by policy changes. We found slight decreases in reported wolf poaching hazard and incidence during six liberalized killing periods, but that was outweighed by larger increases in hazard and incidence of disappearance. Although the observed increase in the hazard of disappearance cannot be definitively shown to have been caused by an increase in cryptic poaching, we discuss two additional independent lines of evidence making this the most likely explanation for changing incidence among n = 513 wolves’ deaths or disappearances during 12 replicated changes in policy. Support for the facilitated poaching hypothesis suggests the increase (11–34%) in disappearances reflects that poachers killed more wolves and concealed more evidence when the government relaxed protections for endangered wolves. We propose a refinement of the hypothesis of ‘facilitated poaching’ that narrows the cognitive and behavioral mechanisms underlying wolf-killing.
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Terraube J, Van Doninck J, Helle P, Cabeza M. Assessing the effectiveness of a national protected area network for carnivore conservation. Nat Commun 2020; 11:2957. [PMID: 32528022 PMCID: PMC7289803 DOI: 10.1038/s41467-020-16792-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 05/20/2020] [Indexed: 11/25/2022] Open
Abstract
Protected areas (PAs) are essential to prevent further biodiversity loss yet their effectiveness varies largely with governance and external threats. Although methodological advances have permitted assessments of PA effectiveness in mitigating deforestation, we still lack similar studies for the impact of PAs on wildlife populations. Here we use an innovative combination of matching methods and hurdle-mixed models with a large-scale and long-term dataset for Finland’s large carnivore species. We show that the national PA network does not support higher densities than non-protected habitat for 3 of the 4 species investigated. For some species, PA effects interact with region or time, i.e., wolverine densities decreased inside PAs over the study period and lynx densities increased inside eastern PAs. We support the application of matching methods in combination of additional analytical frameworks for deeper understanding of conservation impacts on wildlife populations. These methodological advances are crucial for preparing ambitious PA targets post-2020. Assessing the effectiveness of protected areas for wildlife conservation is challenging. Here, Terraube et al. combine statistical matching and hurdle mixed-effects models to show that PAs have limited impact on population densities of large carnivores across Finland.
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Affiliation(s)
- J Terraube
- Global Change and Conservation Lab, Organismal and Evolutionary Biology Research Program. Faculty of Biological and Environmental Sciences, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland.
| | - J Van Doninck
- Amazon Research Team, Department of Biology, University of Turku, 20500, Turku, Finland
| | - P Helle
- Natural Resources Research Institute, Paavo Havaksen tie 3, FI-90570, Oulu, Finland
| | - M Cabeza
- Global Change and Conservation Lab, Organismal and Evolutionary Biology Research Program. Faculty of Biological and Environmental Sciences, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland
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Treves A, Krofel M, Ohrens O, van Eeden LM. Predator Control Needs a Standard of Unbiased Randomized Experiments With Cross-Over Design. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00462] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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11
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Artelle KA, Reynolds JD, Treves A, Walsh JC, Paquet PC, Darimont CT. Hallmarks of science missing from North American wildlife management. SCIENCE ADVANCES 2018; 4:eaao0167. [PMID: 29532032 PMCID: PMC5842039 DOI: 10.1126/sciadv.aao0167] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 02/02/2018] [Indexed: 05/22/2023]
Abstract
Resource management agencies commonly defend controversial policy by claiming adherence to science-based approaches. For example, proponents and practitioners of the "North American Model of Wildlife Conservation," which guides hunting policy across much of the United States and Canada, assert that science plays a central role in shaping policy. However, what that means is rarely defined. We propose a framework that identifies four fundamental hallmarks of science relevant to natural resource management (measurable objectives, evidence, transparency, and independent review) and test for their presence in hunt management plans created by 62 U.S. state and Canadian provincial and territorial agencies across 667 management systems (species-jurisdictions). We found that most (60%) systems contained fewer than half of the indicator criteria assessed, with more criteria detected in systems that were peer-reviewed, that pertained to "big game," and in jurisdictions at increasing latitudes. These results raise doubt about the purported scientific basis of hunt management across the United States and Canada. Our framework provides guidance for adopting a science-based approach to safeguard not only wildlife but also agencies from potential social, legal, and political conflict.
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Affiliation(s)
- Kyle A. Artelle
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
- Raincoast Conservation Foundation, P.O. Box 2429, Sidney, British Columbia V8L 3Y3, Canada
- Hakai Institute, P.O. Box 309, Heriot Bay, British Columbia V0P 1H0, Canada
| | - John D. Reynolds
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Adrian Treves
- Nelson Institute for Environmental Studies, University of Wisconsin–Madison, 30A Science Hall, 550 North Park Street, Madison, WI 53706, USA
| | - Jessica C. Walsh
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Paul C. Paquet
- Raincoast Conservation Foundation, P.O. Box 2429, Sidney, British Columbia V8L 3Y3, Canada
- Department of Geography, University of Victoria, P.O. Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2, Canada
| | - Chris T. Darimont
- Raincoast Conservation Foundation, P.O. Box 2429, Sidney, British Columbia V8L 3Y3, Canada
- Hakai Institute, P.O. Box 309, Heriot Bay, British Columbia V0P 1H0, Canada
- Department of Geography, University of Victoria, P.O. Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2, Canada
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12
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Olson ER, Crimmins SM, Beyer DE, MacNulty DR, Patterson BR, Rudolph BA, Wydeven AP, Van Deelen TR. Flawed analysis and unconvincing interpretation: a comment on Chapron and Treves 2016. Proc Biol Sci 2017; 284:rspb.2017.0273. [PMID: 29167356 PMCID: PMC5719163 DOI: 10.1098/rspb.2017.0273] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 04/13/2017] [Indexed: 11/12/2022] Open
Affiliation(s)
- Erik R Olson
- Natural Resources, Sigurd Olson Environmental Institute, Northland College, Ashland, WI, USA
| | - Shawn M Crimmins
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, USA
| | - Dean E Beyer
- Wildlife Division, Michigan Department of Natural Resources, Marquette, MI, USA
| | - Daniel R MacNulty
- Department of Wildland Resources, Utah State University, Logan, UT, USA
| | - Brent R Patterson
- Ontario Ministry of Natural Resources and Forestry, Wildlife Research and Monitoring Section, Peterborough, Ontario, Canada K9 J 7B8
| | - Brent A Rudolph
- Wildlife Division, Michigan Department of Natural Resources, Lansing, MI, USA
| | - Adrian P Wydeven
- Timber Wolf Alliance, Sigurd Olson Environmental Institute, Northland College, Ashland, WI, USA
| | - Timothy R Van Deelen
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI, USA
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Chapron G, Treves A. Reply to comments by Olson et al. 2017 and Stien 2017. Proc Biol Sci 2017; 284:rspb.2017.1743. [PMID: 29167362 PMCID: PMC5719172 DOI: 10.1098/rspb.2017.1743] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 10/20/2017] [Indexed: 11/21/2022] Open
Affiliation(s)
- Guillaume Chapron
- Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, 73091 Riddarhyttan, Sweden
| | - Adrian Treves
- Nelson Institute for Environmental Studies, University of Wisconsin, 30A Science Hall, 550 North Park Street, Madison, WI 53706, USA
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Stien A. Blood may buy goodwill: no evidence for a positive relationship between legal culling and poaching in Wisconsin. Proc Biol Sci 2017; 284:rspb.2017.0267. [PMID: 29167355 PMCID: PMC5719162 DOI: 10.1098/rspb.2017.0267] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 06/16/2017] [Indexed: 11/25/2022] Open
Affiliation(s)
- Audun Stien
- Norwegian Institute of Nature Research, Fram Centre, NO-9296 Tromsø, Norway
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15
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Affiliation(s)
- Guillaume Chapron
- Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, 73091 Riddarhyttan, Sweden
| | - Adrian Treves
- Nelson Institute for Environmental Studies, University of Wisconsin, 30A Science Hall, 550 North Park Street, Madison, WI 53706, USA
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16
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Treves A, Langenberg JA, López-Bao JV, Rabenhorst MF. Gray wolf mortality patterns in Wisconsin from 1979 to 2012. J Mammal 2017; 98:17-32. [PMID: 29674782 PMCID: PMC5901075 DOI: 10.1093/jmammal/gyw145] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Starting in the 1970s, many populations of large-bodied mammalian carnivores began to recover from centuries of human-caused eradication and habitat destruction. The recovery of several such populations has since slowed or reversed due to mortality caused by humans. Illegal killing (poaching) is a primary cause of death in many carnivore populations. Law enforcement agencies face difficulties in preventing poaching and scientists face challenges in measuring it. Both challenges are exacerbated when evidence is concealed or ignored. We present data on deaths of 937 Wisconsin gray wolves (Canis lupus) from October 1979 to April 2012 during a period in which wolves were recolonizing historic range mainly under federal government protection. We found and partially remedied sampling and measurement biases in the source data by reexamining necropsy reports and reconstructing the numbers and causes of some wolf deaths that were never reported. From 431 deaths and disappearances of radiocollared wolves aged > 7.5 months, we estimated human causes accounted for two-thirds of reported and reconstructed deaths, including poaching in 39-45%, vehicle collisions in 13%, legal killing by state agents in 6%, and nonhuman causes in 36-42%. Our estimate of poaching remained an underestimate because of persistent sources of uncertainty and systematic underreporting. Unreported deaths accounted for over two-thirds of all mortality annually among wolves > 7.5 months old. One-half of all poached wolves went unreported, or > 80% of poached wolves not being monitored by radiotelemetry went unreported. The annual mortality rate averaged 18% ± 10% for monitored wolves but 47% ± 19% for unmonitored wolves. That difference appeared to be due largely to radiocollaring being concentrated in the core areas of wolf range, as well as higher rates of human-caused mortality in the periphery of wolf range. We detected an average 4% decline in wolf population growth in the last 5 years of the study. Because our estimates of poaching risk and overall mortality rate exceeded official estimates after 2012, we present all data for transparency and replication. More recent additions of public hunting quotas after 2012 appear unsustainable without effective curtailment of poaching. Effective antipoaching enforcement will require more accurate estimates of poaching rate, location, and timing than currently available. Independent scientific review of methods and data will improve antipoaching policies for large carnivore conservation, especially for controversial species facing high levels of human-induced mortality.
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Affiliation(s)
- Adrian Treves
- Nelson Institute for Environmental Studies, University of Wisconsin-Madison, 30A Science Hall, 550 North Park Street, Madison, WI 53706, USA (AT)
| | - Julia A Langenberg
- Conservation Science, International Crane Foundation, Baraboo, WI 53913, USA (JAL)
| | - José V López-Bao
- Research Unit of Biodiversity (UO-CSIC-PA), Oviedo University, Oviedo, Mieres 33600, Spain (JVLB)
| | - Mark F Rabenhorst
- Carnivore Coexistence Lab, 30A Science Hall, 550 North Park Street, Madison, WI 53706, USA (MFR)
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