An Assessment of Spatial and Temporal Variation in the Diet of Cape Clawless Otters (Aonyx capensis) in Marine Environments

Abstract

We studied the diet of Cape clawless otters (Aonyx capensis) at three sites along the eastern and southern coast of South Africa to assess possible spatial variation along a community species richness and biomass gradient associated with rocky shores. A total of 309 spraints representing two seasons (summer 2013/2014 and winter 2014) were collected and subsequently analysed. The percentage occurrence and percentage dry mass of numerous prey categories were compared between sites and seasons. Variation in the importance of prey items was found between sites, whilst no variation was found between seasons within the same site. Crab was the most important prey item in the southernmost study area (Tsitsikamma National Park) and at the northernmost study site (KwaZulu-Natal Coast), whilst lobster was the most important prey item in the central area (Mkambati Nature Reserve). Fish was the second most important prey item at all three sites. Our results suggest that otters are opportunistic feeders that are likely able to adapt to potential prey species and abundance changes associated with current and future anthropogenically driven changes. Furthermore, long-term, site-specific stability in diet suggests that monitoring the diet of otters could provide some useful information on the status of shoreline communities.