By William Haase
Geographic Range
Southern river otters, Lontra provocax, 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).
Biogeographic Regions:
neotropical 
(native ).
Habitat
L. provocax 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).
These animals are found in the following types of habitat:
terrestrial ; saltwater or marine ; freshwater .
Aquatic Biomes:
lakes and ponds; rivers and streams; coastal .
Other:
estuarine .
Physical Description
(39.37 to 45.67 in; avg. 42.52 in)
L. provocax 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).
Some key physical features:
endothermic ; bilateral symmetry .
Reproduction
Breeding occurs in the winter and spring, with births occuring the following year.
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. L. provocax 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.
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (internal ); viviparous ; delayed implantation .
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.
Parental investment:
altricial ; female parental care .
Lifespan/Longevity
A high proportion of the individuals die before they reach maturity. Only about 1% will survive to reach 10 years of age. Most L. provocax only live a few years (Chanin, 1985).
Behavior
L. provocax 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).
Food Habits
L. provocax 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).
Animal Foods:
birds; fish; terrestrial non-insect arthropods; mollusks.
Predation
- humans (Homo sapiens)
Humans are known predators (Redford and Eisenberg, 1992). There are no reports of non-human predation on this species.
Ecosystem Roles
This species probably acts as an important control on mollusk, fish, and crustacean populations.
Economic Importance for Humans: Negative
No negastive effects of this species on human populations has been noted.
Economic Importance for Humans: Positive
L. provocax 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).
Conservation Status
Lontra provocax is listed as an endangered species. This is primarily due to illegal hunting, habitat loss and water pollution (Redford and Eisenberg, 1992).
Contributors
William Haase (author), University of Wisconsin-Stevens Point.
Chris Yahnke (editor), University of Wisconsin Stevens Point.
