A survey of the southern river otter Lutra provocax Thomas in Nahuel Huapi National Park, Argentina

Abstract

A survey of the huillin or southern river otter Lutra provocax distribution in Nahuel Huapi National Park was made. This amphibious mustelid is included in the International Union for the Conservation of Nature Red Data Book, and as endangered in the Argentine National Wildlife List. One hundred sites were visited for signs of activity, particularly scats. Twenty-eight sites were positive, all of them in Nahuel Huapi Lake system and tributary water-bodies, where they represent 48·3% of 58 sites. No positive sites were found in the Rio Manso basin, where 13 sites with signs of American mink Mustela vison were recorded. However, it seems improbable that there is significant competitive interference between mink and otter. Although the huillin is not common, there is an apparently viable population in the Nahuel Huapi Lake system, where a high density of signs was found in several places. No significant relation was found between the otter's presence and frequency of human visitors, human settlements, domestic dogs or occurrence of introduced salmonids. Special protection areas and a monitoring programme of otter populations in the National Park are proposed.