The southern river otter is believed to occupy the smallest geographical area of all otter species (3). Like other otters, it is built for swimming, with an elongated, sinuous body, short limbs and webbed feet. The tail is thick at the base and moderately flattened, and the small, round ears, like the nostrils, can be closed underwater (2)(3)(5). The fur is short and sleek, with a dense underfur covered by a layer of glossy guard hairs(5), and the nose and snout bear stiff whiskers, known as vibrissae, which are highly sensitive and used to help locate prey (2). The fur of the southern river otter is dark brown above, with paler underparts and a grey neck and throat (2)(3). The male of this species is usually slightly larger than the female (3)(5).
The diet of the southern river otter consists mainly of fish, although it will also take some crustaceans, and occasionally molluscs and birds (1)(3). This species is most active at night, sheltering during the day in one of a series of dens, which may be located in rock cavities, hollow trees or logs, earth banks, or amongst tree roots. However, some activity may also occur during the day (3). This species is mostly solitary (3).
Relatively little is known about the breeding behaviour of the southern river otter (2). Mating usually occurs in July and August, with the young born between September and October, although in the southern parts of the range young may be seen year-round. Litter size averages one or two young, but up to four have been reported (1)(3). Some otter species show delayed implantation(5), the fertilised eggs not implanting in the uterus immediately and development therefore being delayed, but it is not known whether this occurs in the southern river otter (3).
Although predominantly a freshwater species, occurring in lakes, rivers and streams, the southern river otter also inhabits rocky coastlines in southern Chile. It requires areas of dense vegetation and an abundance of above-ground roots, small rocks and broken stones, which provide crevices from which it can observe the surrounding area (1)(3)(5).
The southern river otter is classified as Endangered (EN) on the IUCN Red List (1) and is listed on Appendix I of CITES (4). It is also listed in the Chilean Red Data Book of Vertebrates as being in danger of extinction, and as Threatened on the Argentine National Wildlife List (1).
The southern river otter has disappeared from much of its original range as a result of habitat destruction and excessive hunting (1)(5), and it is now known from only around seven isolated areas (1). Historically, the species was hunted for its highly priced fur, and despite hunting now being illegal, enforcement is often poor, and illegal poaching is common (1)(3). Habitat loss and degradation also continue to be major threats, as a result of dam construction, the removal of vegetation along riverbanks, river and stream canalisation, drainage for agriculture, and water pollution (1)(3)(5). Large-scale deforestation has also indirectly affected freshwater habitats, causing severe flooding and the deposition of soil on river beds (1). There has also been some concern that the southern river otter may face competition from the introduced American mink, Mustela vison, although this is now believed to be less likely than previously feared (1)(3).
International trade in the southern river otter is banned under its listing on Appendix I of the Convention on International Trade in Endangered Species (CITES) (4), and the species is also listed on Appendix I of the Convention on Migratory Species (CMS) (6). In Argentina, important populations occur in Nahuel Huapi National Park, Tierra del Fuego National Park, and on Staten Island (1)(3)(7). Recommended conservation measures for the southern river otter include population monitoring, improved control of poaching, education measures, and the maintenance of vegetation cover along shorelines. Reintroductions into parts of the species’ former range have also been suggested, provided that anti-poaching legislation is properly enforced (1)(3). The distribution of the southern river otter has been linked to the distribution of crustacean prey, the presence of human habitation, and the presence of introduced mink, and further studies have been recommended to better understand the effects of these factors on the otter’s conservation (7).
Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
The process of a fertilised egg remaining unattached in the uterus for a period of time, therefore delaying the start of development.
The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
In some mammals, long, coarse hairs that protect the softer layer of fur below.
A diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
Nowak, R.M. (1991) Walker’s Mammals of the World. The Johns Hopkins University Press, Baltimore and London.
Convention on the Conservation of Migratory Species of Wild Animals (May, 2010) http://www.cms.int/
Aued, M.B., Chéhebar, C., Porro, G., Macdonald, D.W. and Cassini, M.H. (2003) Environmental correlates of the distribution of southern river otters Lontra provocax at different ecological scales. Oryx, 37(4): 413-421.
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