Bischof, R., Hameed, S., Ali, H., Kabir, M., Younas, M., Shah, K. A., Din, J. U., Nawaz, M. A. (2013). Using time-to-event analysis to complement hierarchical methods when assessing determinants of photographic detectability during camera trapping. Methods in Ecology and Evolution, .
Abstract: 1. Camera trapping, paired with analytical methods for estimating occupancy, abundance and other ecological parameters, can yield information with direct consequences for wildlife management and conservation. Although ecological information is the primary target of most camera trap studies, detectability influences every aspect from design to interpretation.
2. Concepts and methods of time-toevent analysis are directly applicable to camera trapping, yet this statistical field has thus far been ignored as a way to analyze photographic capture data. to illustrate the use to time-to-event statistics and to better understand how photographic evidence accumulates, we explored patterns in tow related measure of detectability: Detection probability and time to detection. We analyzed camera trap data for three sympatric carnivores ( snow Leopard, red fox and stone marten) in the mountains of northern Pakistan and tested predictions about patterns in detectability across species, sites and time.
3. We found species-specific differences in the magnitude of detectability and the factors influencing it, reinforcing the need to consider determinants of detectability in study design and to account for them during analysis. Photographic detectability of snow leopard was noticeably lower than that of red fox, but comparable to detectability of stone marten. Site-specific attributes such as the presence of carnivore sign ( snow Leopard), terrain ( snow leopard and red fox) and application for lures ( red fox) influenced detectability. For the most part, detection probability was constant over time.
4. Species- specific differences in factors determining detectability make camera trap studies targeting multiple species particularly vulnerable to misinterpretation if the hierarchical origin of the data is ignored. Investigators should consider not only the magnitude of detectability, but also the shape of the curve describing the cumulative process of photographic detection, as this has consequences for both determining survey effort and the election of analytical models. Weighted time-to -event analysis can complement occupancy analysis and other hierarchal methods by providing additional tools for exploring camera trap data and testing hypotheses regarding the temporal aspect of photographic evidence accumulation.
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Blomqvist, L. (1993). The snow leopard, Panthera uncia, in captivity during the last 30 years (1961-1991). Helsinki: Helsinki Zoo.
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Blomqvist, L. (1989). Status of the captive snow leopard (Panthera uncia) in 1987.
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Blomqvist, L. (1982). The 1981 annual report of the captive snow leopards (Panthera uncia) population. International Pedigree Book of Snow Leopards, 3.
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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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Blomqvist, L. (1979). The 1978 register for the captive population of snow leopards, Panthera uncia. International Zoo News, 26(7-8), 17–23.
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Blomqvist, L. (1978). First report on the snow leopard studbook (Panthera uncia) and 1976 world register. Int.Zoo Yearbook, 18, 227–231.
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Blomqvist, L., & Dexel, B. (2006). In Focus: Declining numbers of wild snow leopards.
Abstract: International collaboration to ensure the long-term survival of snow leopards (Uncia uncia) in the wild is today more acutely needed than ever! Trade in live snow leopards, their skins and bones, has during the last decade reached such extensiveness that the species is in danger of being wiped out from many of its former habitats. All recent surveys support declining populations throughout most of their range.
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