Mustelidae Author Don E. Wilson Author Russell A. Mittermeier text 2009 2009-01-31 Lynx Edicions Barcelona Handbook of the Mammals of the World – Volume 1 Carnivores 564 656 book chapter http://doi.org/10.5281/zenodo.5714044 df4b6a3c-ae64-4bcf-a990-77fc6599759c 978-84-96553-49-1 5714044 31. Southern River Otter Lontra provocax French: Loutre du Chili / German: Patagonischer Fischotter / Spanish: Huillin Other common names: Huillin Taxonomy. Lutra provocax Thomas, 1908 , Patagonia. Monotypic. Distribution. Argentina and Chile . Descriptive notes. Head-body 57-61 cm , tail 35-40 cm ; weight 5-10 kg , males are about 10% larger than females. This medium-sized otter is dark-brown with pale undersides and a grayish neck and throat. All four feet are fully webbed. The skull is flat, but strongly built. The dentition is broad and adapted for crushing. Habitat. Southern River Otters are found in lakes, rivers, and some coastal marshes. In Argentina , they are associated with dense mature forests that have thick undergrowth extending close to the shore of water bodies. In southern Chile , radio-tracked Southern River Otters used rivers more frequently than expected, whereas they avoided small streams. Temperate evergreen swamp forests and river and stream banks with a high density of riparian vegetation, woody debris and exposed roots, were found to be the preferred habitats; canalized rivers and streams lacking these characteristics were avoided. Food and Feeding. The diet is mostly fish (under 10 cm in length) and crustaceans, but also includes molluscs and birds. The relative importance of each food type may vary seasonally or geographically. In central Chile , the diet comprises 75% fish and 63% crustaceans; the highest occurrence of fish occurs in the spring and summer. In the southern marine habitats of Chile , Southern River Otters feed mainly on fish. In Argentina , crustaceans largely dominate the diet (99%) and fish occur rarely (less than 2%). Differences in the proportion offish and crustaceans in the diet may reflect the differential availability of prey types in different habitats: fish productivity is low in freshwater lakes compared to the oceans, which may explain the high proportion of crustaceans in freshwater lakes. Activity patterns. Primarily nocturnal, with occasional activity during the day. Den/ rest sites are rock crevices, hollow trees or logs, earth banks, or under root systems; Southern River Otters may excavate their own dens. Dens occur from 0-7 to 50 m from the shoreline; most are within 3-8 m of the water’s edge. They often have multiple terrestrial but no underwater entrances. The density of dens along the southern coast of Chile was 2-8 per km of coastline. Latrines are common near den entrances or inside dens; they are 50-80 m from one another and 3-6 m from water. Movements, Home range and Social organization. Southern River Otters may move up to 5 km per night. They are mostly solitary; females with young and breeding pairs are the only social groups recorded. In the Queule River, southern Chile , the observed behavior of radio-tracked otters suggested intra-sexual territoriality; no home range overlap among males existed, while there was an average of 33% overlap of home ranges among females, and 87% between sexes. In core areas, only one case of overlapping between an adult male and an adult female was observed. Average home range and core area lengths were 11- 3 km and 0-9 km , respectively. The population density in Chile ranges from 0-25 to 0-73 individuals per km of coastline. Breeding. In central Chile , mating occurs in July and August, and young are born in September or October. Litter size averages one or two, but may reach up to four. Status and Conservation. CITES Appendix I. Classified as Endangered in The IUCN Red List. The major threats to this species are the destruction ofits habitat and hunting, especially in Chile . The high price of otter skins in Chile , combined with low wages for unskilled workers, generates much uncontrolled and illegal harvest. Bibliography. Aued et al. (2003), Chéhébar (1986), Chéhébar et al. (1986), Lariviere (1999¢), Medina (1996), Medina et al. (2003), Sielfeld (1983), Van Zyll de Jong (1972), Wozencraft (2005).