Shoot, shovel and shut up: cryptic poaching slows restoration of a large carnivore in Europe

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 279; no. 1730; pp. 910 - 915
• Main Authors: Liberg, Olof, Chapron, Guillaume, Wabakken, Petter, Pedersen, Hans Christian, Hobbs, N. Thompson, Sand, Håkan
• Format: Journal Article
• Language: English
• Published: England The Royal Society 07.03.2012
• Subjects: Animals; Carnivores; Conservation; Conservation biology; Ecological modeling; Ecology; Ekologi; Endangered Species; Europe; Human Activities; Humans; Markov Chains; Models, Theoretical; Monte Carlo Method; Mortality; Poaching; Population Density; Population Dynamics; Population estimates; Population growth; Population size; State–space Models; Wolf; Wolves; Europe
• ISSN: 0962-8452; 1471-2954; 1471-2954
• DOI: 10.1098/rspb.2011.1275

Poaching is a widespread and well-appreciated problem for the conservation of many threatened species. Because poaching is illegal, there is strong incentive for poachers to conceal their activities, and consequently, little data on the effects of poaching on population dynamics are available. Quantifying poaching mortality should be a required knowledge when developing conservation plans for endangered species but is hampered by methodological challenges. We show that rigorous estimates of the effects of poaching relative to other sources of mortality can be obtained with a hierarchical state-space model combined with multiple sources of data. Using the Scandinavian wolf (Canis lupus) population as an illustrative example, we show that poaching accounted for approximately half of total mortality and more than two-thirds of total poaching remained undetected by conventional methods, a source of mortality we term as 'cryptic poaching'. Our simulations suggest that without poaching during the past decade, the population would have been almost four times as large in 2009. Such a severe impact of poaching on population recovery may be widespread among large carnivores. We believe that conservation strategies for large carnivores considering only observed data may not be adequate and should be revised by including and quantifying cryptic poaching.