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Scat DNA Testing Permits Accurate Counting of Tigers

A study describing the successful application of fecal DNA testing to the accurate counting of tigers has been published by scientists from the Wildlife Conservation Society (WCS) and collaborating institutions. By testing the DNA in individual samples of tiger scat in a particular area, the scientists were able to obtain unique DNA signatures for particular tigers and use these data in computer models to estimate the tiger population in the area. "This study is a breakthrough in the science of counting tiger numbers, which is a key yardstick for measuring conservation success," said noted tiger scientist Dr. Ullas Karanth of the WCS, and an author of the study. "The technique will allow researchers to establish baseline numbers on tiger populations in places where they have never been able to accurately count them before." The study took place in India's Bandipur Reserve in Karnataka, a long-term WCS research site in the Western Ghats that supports a high abundance of tigers. Researchers collected 58 tiger scats following rigorous protocols, then identified individual animals through their DNA. Tiger populations were then estimated using sophisticated computer models. These results were validated against camera trap data, where individual tigers are photographed automatically and identified by their unique stripe patterns. Camera-trapping is considered the gold standard in tiger population estimation, but is impractical in several areas where tiger densities are low or field conditions too rugged. "We see genetic sampling as a valuable additional tool for estimating tiger abundance in places like the Russian Far East, Sunderban mangrove swamps, and dense rainforests of Southeast Asia where camera trapping might be impractical due to various environmental and logistical constraints," said Dr. Karanth. This article, entitled “Evaluation of Non-Invasive Genetic Sampling Methods for Estimating Tiger Population Size” was published online on June 17 in Biological Conservation. [Press release]