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Résumé :
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Context. Distance sampling is widely used to estimate the size of wildlife populations, including kangaroos. However, the performance of distance-sampling abundance estimates has seldom been evaluated for wild mammal populations of known size. Aims. Weevaluated the precision, accuracy, bias and interval coverage of abundance estimates from walked line-transect sampling, a commonly used distance-sampling method, for a marked free-ranging population of eastern grey kangaroos (Macropus giganteus) at Yanakie Isthmus, Wilsons Promontory National Park, south-eastern Australia. Methods. In each of two study periods (November 2012 and May 2013) we first determined the true size of the uniquely marked kangaroo population by conducting 10 intensive searches of the study area. We then conducted distance sampling along six systematically spaced line transects. Wewalked each transect four times in November 2012 and seven times in May 2013. Data were analysed using Program DISTANCE. Key results. Our intensive searches revealed that 141 and 124 collared kangaroos were present in the study area in November 2012 and May 2013, respectively. When transects were walked four or more times (i. e. >= 400 observations), maximum precision (coefficient of variation; CVof similar to 13%) was achieved in both survey periods. Walking transects twice (i. e. similar to 200 observations) produced abundance estimates with CVs of
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