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Karanth, K.U.; Nichols, J.D.; Kumar, N.S.
Estimating tiger abundance from camera trap data: field surveys and analytical issues
2011  Book Chapter

Automated photography of tigers Panthera tigris for purely illustrative purposes was pioneered by British forester Fred Champion (1927, 1933) in India in the early part of the Twentieth Century. However, it was McDougal (1977) in Nepal who first used camera traps, equipped with single-lens reflex cameras activated by pressure pads, to identify individual tigers and study their social and predatory behaviors. These attempts involved a small number of expensive, cumbersome camera traps, and were not, in any formal sense, directed at "sampling" tiger populations. Karanth (1995) first employed camera traps as a population sampling tool, using tiger photos to generate capture histories that were then used to estimate population size (abundance) in a closed model capture-recapture (CR) framework (Otis et al. 1978; White et al. 1982). Although this post-hoc analysis partially shoe-horned data into a CR framework, it did lead to identification of key issues related to trap-spacing, population closure, model selection and density estimation. These issues were addressed in subsequent refinements introduced by Karanth and Nichols (1998), and were elaborated in a technical manual (Karanth and Nichols 2002). Thereafter, several camera trap studies have tried to estimate tiger abundance using the Karanth-Nichols approach (Karanth et al. 2004a,b, 2006; Kawanishi and Sunquist 2004; Simcharoen et al. 2007) or variations on it (O'Brien et al. 2003; Wegge et al. 2004; Johnson et al. 2006). The material in this chapter will be based on the approach advocated by Karanth and Nichols (1998, 2002). This approach is sound and can be implemented with existing software at this time.

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