Habitat use and diet of endangered southern river otter Lontra provocax in a predominantly palustrine wetland in Chile

Abstract

The southern river otter Lontra provocax is an endangered species. It has a patchy distribution in southern Chile and Argentina, inhabiting both freshwater and marine habitats. While most studies of their diet and habitat use have been carried out in freshwater habitats, our study is the first one on these aspects in a predominantly palustrine wetland. In southern Chile, the Boroa wetland may be the only wetland with southern river otters and five different subsystems: palustrine open water, swamp forest, seasonal and permanent marshes, and riverine associated with open farm fields. We studied these five different subsystems during April 2003 - May 2004, and collected and analysed 194 spraints in order to assess the effect of rainfall and subsystems on the diet and sprainting behaviour of southern river otter. The river otter's diet primarily consisted of crustaceans; however, rainfall and wetland subsystems influenced the frequency of fish and especially amphibians in the spraints collected. This is the first study documenting the helmeted water toad Caudiverbera caudiverbera as a prey of southern river otter. Southern river otter visited latrines located within the swamp forest more frequently, as this subsystem may provide refuge for latrines and dens as well as an important supplementary feeding resource. Our study provides insights into the role of coastal wetlands in predation processes, and highlights the importance of ecosystem services derived from wetland for biodiversity conservation. However, it is of concern that these wetlands are increasingly affected by drainage for agriculture and other landscape changes in southern Chile.