EDITOR'S CHOICE: Safeguarding Sumatran tigers: evaluating effectiveness of law enforcement patrols and local informant networks

Summary The United Nations recently listed illegal wildlife trade as a serious crime because of the escalating demand for highly prized species, such as tiger and rhinoceros, and the failure to effectively control the trade. In turn, this places greater urgency on reducing supply by securing source populations of these species. Yet, whether law enforcement strategies designed to mitigate poaching are succeeding remains poorly understood, despite the millions of dollars invested annually in this mainstay conservation strategy. Here, we assess the performance of one of Asia's longest running law enforcement programmes, from Kerinci Seblat National Park in Sumatra, by investigating whether forest ranger patrols reduced the occurrence of snare traps set for tiger and its ungulate prey base; local informant reports on poaching influenced ranger patrol success; and the resulting population trends of target species changed in response to these conservation actions. A total of 4433 snare traps were removed during 642 foot patrols conducted from 2000 to 2010. Controlling for the influence of varying detection probabilities, as well as accessibility and other possible determinants of illegal hunting, revealed that sites with a greater frequency of patrols, rather than the combined distance walked, had a lower occurrence of snare traps in succeeding years. Patrols conducted on the basis of local informant ‘tip-offs’ were significantly more likely to detect snare traps than routine patrols, with reports increasing detections by over 40%. There were no significant changes in the occupancy status of the tiger prey base from 2004 to 2011, suggesting that it remained stable during this period. The relatively good condition of prey and predator populations in Kerinci Seblat National Park was further supported by the results of an independent survey conducted in 2008–2009 which revealed a widespread tiger occurrence. Synthesis and applications. Our results not only demonstrate the effectiveness of the Kerinci Seblat law enforcement strategy in protecting wildlife, but highlight the benefits from cultivating a network of reliable informants. The study also represents a critical step in helping these urgently needed conservation assessments to become common place in the fight to save flagship species.

[1]  E. Wikramanayake,et al.  The Fate of Wild Tigers , 2007 .

[2]  Brendan A. Wintle,et al.  Imperfect detection impacts the performance of species distribution models , 2014 .

[3]  I. Chades,et al.  When to stop managing or surveying cryptic threatened species , 2008, Proceedings of the National Academy of Sciences.

[4]  M. Linkie,et al.  Breaking the Vicious Circle of Illegal Logging in Indonesia , 2014, Conservation biology : the journal of the Society for Conservation Biology.

[5]  Natalia Pervushina,et al.  Reduced to skin and bones revisited , 2013 .

[6]  Guy Cowlishaw,et al.  Do wildlife laws work? Species protection and the application of a prey choice model to poaching decisions , 2004, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[7]  Yoan Dinata,et al.  Conserving tigers Panthera tigris in selectively logged Sumatran forests , 2008 .

[8]  N. Leader‐Williams,et al.  Illegal exploitation of black rhinoceros and elephant populations : patterns of decline, law enforcement and patrol effort in Luangwa Valley, Zambia , 1990 .

[9]  C. Yackulic,et al.  The spatial structure of hunter access determines the local abundance of forest elephants (Loxodonta africana cyclotis). , 2011, Ecological applications : a publication of the Ecological Society of America.

[10]  Kristine N. Stewart,et al.  Averting biodiversity collapse in tropical forest protected areas , 2012, Nature.

[11]  J. Nichols,et al.  Monitoring carnivore populations at the landscape scale: occupancy modelling of tigers from sign surveys , 2011 .

[12]  M. Chhowalla.  Synthesis and Applications , 2016 .

[13]  T. Gray,et al.  Establishing a monitoring baseline for threatened large ungulates in eastern Cambodia , 2012 .

[14]  José J. Lahoz-Monfort,et al.  Population Status of a Cryptic Top Predator: An Island-Wide Assessment of Tigers in Sumatran Rainforests , 2011, PloS one.

[15]  A. Roth,et al.  The shuttle radar topography mission—a new class of digital elevation models acquired by spaceborne radar , 2003 .

[16]  D. MacKenzie.  Occupancy Estimation and Modeling: Inferring Patterns and Dynamics of Species Occurrence , 2005 .

[17]  E. Stokstad.  The empty forest. , 2014, Science.

[18]  Kathy MacKinnon,et al.  Bringing the Tiger Back from the Brink—The Six Percent Solution , 2010, PLoS biology.

[19]  I. Chades,et al.  Allocating conservation resources between areas where persistence of a species is uncertain. , 2011, Ecological applications : a publication of the Ecological Society of America.

[20]  R. Harrison.  Emptying the Forest: Hunting and the Extirpation of Wildlife from Tropical Nature Reserves , 2011 .

[21]  N. Leader‐Williams,et al.  Assessing the viability of tiger subpopulations in a fragmented landscape , 2006 .

[22]  K. Redford,et al.  Effects of Landscape Features on the Distribution and Sustainability of Ungulate Hunting in Northern Congo , 2011, Conservation biology : the journal of the Society for Conservation Biology.

[23]  K. U. Karanth,et al.  Ecologists need robust survey designs , sampling and analytical methods , 2015 .

[24]  K. Redford.  The Empty Forest Many large animals are already ecologically extinct in vast areas of neotropical forest where the vegetation still appears intact , 1992 .

[25]  J. Andrew Royle,et al.  ESTIMATING SITE OCCUPANCY RATES WHEN DETECTION PROBABILITIES ARE LESS THAN ONE , 2002, Ecology.

[26]  David R. Anderson,et al.  Model selection and multimodel inference : a practical information-theoretic approach , 2003 .

[27]  M. Linkie,et al.  Conserving tigers in Malaysia: A science-driven approach for eliciting conservation policy change , 2015 .

[28]  Michael R. Miller,et al.  Hunting influences the diel patterns in habitat selection by northern pintails Anas acuta , 2012 .

[29]  E. Bennett.  Another inconvenient truth: the failure of enforcement systems to save charismatic species , 2011, Oryx.

[30]  J. Nichols,et al.  Tigers and their prey: Predicting carnivore densities from prey abundance. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[31]  Subhrendu K. Pattanayak,et al.  Money for Nothing? A Call for Empirical Evaluation of Biodiversity Conservation Investments , 2006, PLoS biology.

[32]  H. Prins,et al.  Factors influencing the distribution of large mammals within a protected central African forest , 2005, Oryx.

[33]  David R. Anderson,et al.  Statistical inference from capture data on closed animal populations , 1980 .

[34]  J. Andrew Royle,et al.  Tigers on trails: occupancy modeling for cluster sampling. , 2009, Ecological applications : a publication of the Ecological Society of America.

[35]  A. Cropper.  Convention on Biological Diversity , 1993, Environmental Conservation.

[36]  H. Jachmann,et al.  Elephant poaching and law enforcement in the central Luangwa Valley, Zambia , 1997 .

[37]  Kenneth H. Pollock,et al.  FORUM: Ecologists need robust survey designs, sampling and analytical methods , 2015 .

[38]  J. Nichols,et al.  ESTIMATION OF TIGER DENSITIES IN INDIA USING PHOTOGRAPHIC CAPTURES AND RECAPTURES , 1998 .

[39]  E. Milner‐Gulland,et al.  Policies for the enforcement of Wildlife laws : the balance between detection and penalties in Luangwa Valley, Zambia , 1993 .

[40]  N. Leader‐Williams,et al.  Quantifying changes in sun bear distribution and their forest habitat in Sumatra , 2013 .

[41]  E. J. Milner-Gulland,et al.  Encounter data in resource management and ecology: pitfalls and possibilities , 2011 .

[42]  Evaluating the performance of a decade of Save The Tiger Fund's investments to save the world's last wild tigers , 2007, Environmental Conservation.

[43]  E. Milner‐Gulland,et al.  A model of incentives for the illegal exploitation of black rhinos and elephants : poaching pays in Luangwa Valley, Zambia , 1992 .