Detecting wildlife poaching 579
and presents a method that could be modified for use in other environments and for other types of poaching. By using an experimental design with a known spatial distribu- tion of imitation snares,we estimated the baseline probability of ranger teams detecting snares, and evaluated alternative patrol strategies. Although detection probabilities were gen- erally low, the highest proportion of imitation snares was de- tected with systematic search strategies. Future studies can build upon these findings by using a similar design to explore other factors such as seasonality and vegetation.
Acknowledgements This research received no specific grant from any funding agency, commercial or not-for-profit sectors. We thank the Black Mambas Anti-Poaching Unit for their hard work patrolling the Reserve; the management of Olifants West Nature Reserve and its landowners for their permission; Chris Farren, Leonie Hofstra, Lisa Trueman, Barrie Venter, and Jacques Viljoen for their help with organ- izing and managing the snare searches; and the volunteers and re- searchers at Transfrontier Africa NPC for their help: Chris Banotai, Manuela Böhm, Linda Crawford, Jay Daniel, Amy Dennett, Emma Germano, Joni Hartman, Romana Kremlácková, Kyra Reumerman, Marc Saadi-Clark, Frouwke Smidt, Siboniso Thela, Isabelle Tiller, Beatriz d’Vaz, and Florence Wiggins. We thank Marie Lindegaard, Wouter Steenbeek and two anonymous reviewers for their comments.
Author contributions Study design: all authors; fieldwork: NvD, PMRRA, CRS; data analysis: NvD, AML, SR; writing: NvD, AML, SR, PMRRA.
Conflicts of interest None.
Ethical standards This study abided by the Oryx guidelines on eth- ical standards, and was approved by the relevant authorities of Olifants West Nature Reserve and by the Ethics Committee for Legal and Criminological Research of the Vrije Universiteit Amsterdam.
References
BAYLIS, K., HONEY-ROSÉS, J., BÖRNER, J., CORBERA, E., EZZINE-DE-BLAS, D., FERRARO, P.J. et al. (2016) Mainstreaming impact evaluation in nature conservation. Conservation Letters, 9, 58–64.
BECKER, M., MCROBB, R.,WATSON, F., DROGE, E., KANYEMBO, B., MURDOCH,J.&KAKUMBI,C.(2013) Evaluating wire-snare poaching trends and the impacts of by-catch on elephants and large carnivores. Biological Conservation, 158, 26–36.
BURTON, A.C. (2012) Critical evaluation of a long-term, locally-based wildlife monitoring program inWest Africa. Biodiversity and Conservation, 21, 3079–3094.
CACHO, O.J., HESTER,S. & SPRING,D.(2007) Applying search theory to determine the feasibility of eradicating an invasive population in natural environments. Australian Journal of Agricutural and Resource Economics, 51, 425–443.
CEE (2013) Guidelines for Systematic Review and Evidence Synthesis in Environmental Management. Version 4.2. Environmental Evidence.
environmentalevidence.org/wp-content/uploads/2014/06/Review- guidelines-version-4.2-final.pdf [accessed 21 June 2020].
CHEN, L.F.,VANDERWEG,M.W.,HOFMANN, D.A.&REISINGER, H.S. (2015) The Hawthorne effect in infection prevention and epidemiology. Infection Control and Hospital Epidemiology, 36, 1444–1450.
CHUNG, T.H. & BURDICK, J.W. (2007) A decision-making framework for control strategies in probabilistic search. In Proceedings 2007 IEEE International Conference on Robotics and Automation, pp. 4386–4393. Rome, Italy.
CRITCHLOW, R., PLUMPTRE, A.J., ALIDRIA, B., NSUBUGA, M., DRICIRU, M., RWETSIBA,
A.etal. (2017) Improving law- enforcement effectiveness and efficiency in protected areas using ranger-collected monitoring data. Conservation Letters, 10, 572–580.
CRITCHLOW, R., PLUMPTRE, A.J., DRICIRU, M., RWETSIBA, A., STOKES, E.J., TUMWESIGYE, C. et al. (2015) Spatiotemporal trends of illegal activities from ranger-collected data in a Ugandan National Park. Conservation Biology, 29, 1458–1470.
DELANEY, D.G. & LEUNG,B.(2010) An empirical probability model of detecting species at low densities. Ecological Applications, 20, 1162–1172.
DOBSON, A.D.M., MILNER-GULLAND, E.J., BEALE, C.M., IBBETT,H. &KEANE,A.(2019) Detecting deterrence from patrol data. Conservation Biology, 33, 665–675.
FANG, F., NGUYEN, T.H., PICKLES, R., LAM,W.Y., CLEMENTS, G.R., AN, B. et al. (2017)PAWS – A deployed game-theoretic application to combat poaching. AI Magazine, 38, 23–36.
FAY, M.P. (2010) Confidence intervals that match Fisher’s exact or Blaker’s exact tests. Biostatistics, 11, 373–374.
GAVIN, M.C., SOLOMON, J.N. & BLANK, S.G. (2010) Measuring and monitoring illegal use of natural resources. Conservation Biology, 24, 89–100.
GRAY, T.N.E., HUGHES, A.C., LAURANCE,W.F., LONG, B., LYNAM, A.J., O’KELLY, H. et al. (2018) The wildlife snaring crisis: an insidious and pervasive threat to biodiversity in Southeast Asia. Biodiversity and Conservation, 27, 1031–1037.
HARVEY, S.A.,OLÓRTEGUI, P.M., LEONTSINI,E.&WINCH, P.J. (2009) ‘They’ll change what they’re doing if they know that you’re watching’: measuring reactivity in health behavior because of an observer’s presence – A case from the Peruvian Amazon. Field Methods, 21, 3–25.
HILBORN, R., ARCESE, P., BORNER, M., HANDO, J., HOPCRAFT, G., LOIBOOKI,M. et al. (2006) Effective enforcement in a conservation area. Science, 314, 1266.
HUNTER, L.T.B., PRETORIUS, K., CARLISLE, L.C., RICKELTON, M., WALKER, C., SLOTOW,R. & SKINNER, J.D. (2007) Restoring lions Panthera leo to northern KwaZulu-Natal, South Africa: short-term biological and technical success but equivocal long-term conservation. Oryx, 41, 196–204.
IBBETT, H., MILNER-GULLAND, E.J., BEALE, C., DOBSON, A.D.M., GRIFFIN, O., O’KELLY,H. & KEANE,A. (2020) Experimentally assessing the effect of search effort on snare detectability. Biological Conservation, 247, 108581.
JOHNSON, A., GOODRICH, J., HANSEL, T., RASPHONE, A., SAYPANYA, S., VONGKHAMHENG, C. et al. (2016) To protect or neglect? Design, monitoring, and evaluation of a law enforcement strategy to recover small populations of wild tigers and their prey. Biological Conservation, 202, 99–109.
JOHNSON, S.D., TILLEY,N. & BOWERS, K.J. (2015) Introducing EMMIE: an evidence rating scale to encourage mixed-method crime prevention synthesis reviews. Journal of Experimental Criminology, 11, 459–473.
JONES, J.P.G. (2018) More experiments may help explore what works in conservation. The Conversation, 5 November 2018. theconversation. com/more-experiments-may-help-explore-what-works-in- conservation-106190 [accessed 15 July 2020].
KAPLAN, E.L. & MEIER,P.(1958) Nonparametric estimation from incomplete observations. Journal of the American Statistical Association, 53, 457–481.
Oryx, 2022, 56(4), 572–580 © The Author(s), 2021. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605320001301
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