Southern river otters,, are only found in central and southern Chile and parts of Argentina. This species has been exterminated from much of its range in Chile by hunting. In Argentina, it is found along the Andes from Tierra del Fuego all the way to the southern part of Neuquen province (Otternet, 1998).
inhabits both marine and fresh waters. It is found on rocky coasts and in protected canals in areas where there are few waves. It does not live in open coastal areas, but instead prefers coastal and freshwater environments with dense vegetation (Redford and Eisenberg, 1992).
is a medium sized otter. It ranges from 1000 mm to 1160 mm in total length. Its tail is 350 to 460 mm long. These otters possess webbed feet with strong claws. Their hair has a velvety texture. The guard hairs range in length from 15 to 17 mm, and the under fur is 7 to 8 mm long. The dorsum is a very dark brown, which strongly contrasts with the silvery whitish ventrum. Their nose is diamond-shape with the bottom corner squared off (Otternet, 1998).
The mating system of this species has not been reported.
River otters typically breed in the winter and spring, with births taking place the following year. Because there is a delay between mating and implantation of the fertilized eggs, there can be a great variability in the length of pregnancy. Although gestation has been reported to be 10-12 months long, actual embryonic development is around two months (Nowak, 1999).
Females have four nipples and produce one to four young each season, but usually produce only one or two young.young are born a helpless, blind and scarcely mobile. Young spend their time in the den either suckling or sleeping. The milk is an extremely rich energy source and the young have a high metabolic rate. They open their eyes at approximately one month and begin to eat solid foods at 7 weeks. They begin to swim at about 3 months of age. They are usually capable of catching their own food within 4 months. The young remain with the family group for the first year before they disperse (Chanin, 1985). Reproductive maturity is attained in the second or third year of life.
As in all mammals, the female provides milk for her offspring. Young are altricial and are cared for by the mother until they disperse. Other aspects of parental care in this species are not known.
A high proportion of the individuals die before they reach maturity. Only about 1% will survive to reach 10 years of age. Mostonly live a few years (Chanin, 1985).
tends to be found in family groups that consist of the adult female and her young. Males are usually solitary except during the mating season. Males also tend to have a larger home range than family groups. Both sexes of this species are usually active during the night (Chanin, 1985).
diet varies within the separate habitat types. In a Chilean population, 75% of fecal samples analyzed had fish in them, and 63% had crustaceans. In Argentina the feces showed 99% of scats had crustaceans and only 2% contained fish (Medina, 1998). In addition to fish and crustaceans, southern river otters also eat mollusks and birds (Kruuk, 1995).
Humans are known predators (Redford and Eisenberg, 1992). There are no reports of non-human predation on this species.
This species probably acts as an important control on mollusk, fish, and crustacean populations.
was harvested for its fur, but it is now illegal to harvest these animals. However, poachers are still a threat to this species (Redford and Eisenberg 1992).
No negastive effects of this species on human populations has been noted.
is listed as an endangered species. This is primarily due to illegal hunting, habitat loss and water pollution (Redford and Eisenberg, 1992).
William Haase (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.
living in the southern part of the New World. In other words, Central and South America.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
parental care is carried out by females
union of egg and spermatozoan
mainly lives in water that is not salty.
fertilization takes place within the female's body
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
an animal that mainly eats fish
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
Chanin, P. 1985. The Natural History of Otters. New York: Facts on File.
Kruuk, H. 1995. Wild Otters: Predation and Population. New York: Oxford University Press.
Medina, G. Sept., 1998. Seasonal variations and changes in the diet of southern river otter in different freshwater habitats in Chile. Acta-Theriologica, 43 (3): 285-292.
Otternet, 1998. "Species Profile: Southern River Otter" (On-line). Accessed October 28, 2001 at http://www.otternet.com/species/srotter.htm.
Redford, K., J. Eisenberg. 1992. Mammals of the Neotropics: The Southern Cone Vol. 2. Chicago, IL: University of Chicago Press.