Nawaz, M. A., Khan, B. U., Mahmood, A., Younas, M., Din, J. U, Sutherland, C. (2021). An empirical demonstration of the effect of study design on density estimations. Nature, 11(13104), 1–9.
Abstract: The simultaneous development of technology (e.g. camera traps) and statistical methods, particularly spatially capture–recapture (SCR), has improved monitoring of large mammals in recent years. SCR estimates are known to be sensitive to sampling design, yet existing recommendations about trap spacing and coverage are often not achieved, particularly for sampling wide-ranging and rare species in landscapes that allow for limited accessibility. Consequently, most camera trap studies on large wide-ranging carnivores relies on convenience or judgmental sampling, and often yields compromised results. This study attempts to highlight the importance of carefully considered sampling design for large carnivores that, because of low densities and elusive behavior, are challenging to monitor. As a motivating example, we use two years of snow leopard camera trapping data from the same areas in the high mountains of Pakistan but with vastly different camera configurations, to demonstrate that estimates of density and space use are indeed sensitive to the trapping array. A compact design, one in which cameras were placed much closer together than generally recommended and therefore have lower spatial coverage, resulted in fewer individuals observed, but more recaptures, and estimates of density and space use were inconsistent with expectations for the region. In contrast, a diffuse design, one with larger spacing and spatial coverage and more consistent with general recommendations, detected more individuals, had fewer recaptures, but generated estimates of density and space use that were in line with expectations. Researchers often opt for compact camera configurations while monitoring wide-ranging and rare species, in an attempt to maximize the encounter probabilities. We empirically demonstrate the potential for biases when sampling a small area approximately the size of a single home range—this arises from exposing fewer individuals than deemed sufficient for estimation. The smaller trapping array may also underestimate density by significantly inflating
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Blomqvist, L. (1982). Snow leopard references 3. In L. Blomqvist (Ed.), International Pedigree Book of Snow Leopards (pp. 173–175). Helsinki: Helsinki Zoo.
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Blomqvist, L. (1981). The 1980 annual report of the captive snow leopard (Panthera uncia) population and a review at the breeding results during the 1970's. Helsinki Zoo Annual Report. Helsinki: Helsinki Zoo.
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Blomqvist, L. (1980). The 1979 world register for the captive population of snow leopards, Panthera uncia. In L. Blomqvist (Ed.), International Pedigree Book of Snow Leopards (pp. 62–75). Helsinki: Helsinki Zoo.
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Mainka, S. A. (1986). Snow leopard surgery. Calgary Zoo Newsletter, , 10.
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Anonymous. (2000). A snow leopard conservation plan for Mongolia.
Abstract: The snow leopard faces multiple threats in the Himalayan region, from habitat degradation, loss of prey, the trade in pelts, parts and live animals, and conflict with humans, primarily pastoralists. Consequently, the populations are considered to be in decline and the species is listed as Endangered in the IUCN's Red List. As a 'flagship' and 'umbrella' species the snow leopard can be a unifying biological feature to raise awareness of its plight and the need for conservation, which will benefit other facets of Himalayan biodiversity as well. Some studies of snow leopards have been conducted in the Himalayan region. But, because of its elusive nature and preference for remote and inaccessible habitat, knowledge of the ecology and behaviour of this mystical montane predator is scant. The available information, however, suggests that snow leopards occur at low densities and large areas of habitat are required to conserve a viable population. Thus, many researchers and conservationists have advocated landscape-scale approaches to conservation within a regional context, rather than focusing on individual protected areas.This regional strategy for WWF's snow leopard conservation program is built on such an approach. The following were identified as important regional issues: 1) international trade in snow leopards and parts; 2) the human-snow leopard conflict; 3) the need for a landscape approach to conservation to provide large spatial areas that can support demographically and ecologically viable snow leopard metapopulations; 4) research on snow leopard ecology to develop long-term, science-based conservation management plans; and 5) regional coordination and dialog. While the issues are regional, the WWF's in the region have developed 5-year strategic actions and activities, using the regional strategies as a touchstone, which will be implemented at national levels. The WWF's will develop proposals based on these strategic actions, with estimated budgets, for use by the network for funding and fund-raising. WWF also recognizes the need to collaborate and coordinate within the network and with other organizations in the region to achieve conservation goals in an efficient manner, and will form a working group to coordinate activities and monitor progress.
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Anonymous. (2001). Snow leopard conservancy annual report, 2001. Los Gatos, California, USA: Snow Leopard Conservancy.
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Anonymous. (2000). Snow leopard management plan of Mongolia (draft).
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Dexel, B. (2001). Snow leopard conservation: a NABU project in Kyrgyzstan. Oryx, 35(4), 354–355.
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Shah, K. B. (1989). On a hunting pair of snow leopards in western Nepal. Journal of Bombay Natural Historical Society, 86, 236–237.
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