Factors determining occupancy and habitat use by Asian small-clawed otters in the Western Ghats, India

We examined patterns of habitat occupancy and intensity of habitat use by Asian small-clawed otters (Aonyx cinerea) by sampling 59 hill stream segments in the Western Ghats between February and April 2008, using spraints (otter feces) as an indicator. We used an occupancy-based approach to determine the influence of habitat covariates on detection and occupancy. We also used generalized linear models to model encounter rate of spraints as a function of the habitat covariates. Although occupancy of streams was high before summer showers, it declined drastically after the rains. Sampling time, therefore, indicated otter movement across the area. Altitude was the next-best predictor of occupancy. Intensity of habitat use was influenced most by altitude followed by stream type, with pools preferred over cascades and riffles. Second- and 3rd-order streams were used more intensively than 1st-order streams. The study identifies high-altitude areas with stream pools as important prospective otter habitats and demonstrates the applicability of occupancy-based surveys to identify determinants of occurrence and habitat use of otters.