This species is extremely territorial during the breeding season. Males take up territories in November, which they defend rigorously, and are joined two weeks later by females.

Statistics
Males (bulls): 2m, 150-200kg, Females (cows): 1.5m, 30-60kg.

Physical description
Adult males are dark grey and females are a slightly lighter shade. The males have longer hair on the neck and shoulders. Their range overlaps that of the South American sea lion, but they can be distinguished by their smaller size and less robust muzzle.

Distribution
These fur seals are distributed around the coast of South America, as far north as southern Brazil.

Diet
Anchovies, sardines and other fish species are important prey items, as well as invertebrates including crabs, shrimps, squid and mussels. They will also hunt penguins.

Behaviour
Killer whales and large sharks hunt these fur seals, and juveniles are often killed by South American sea lions.

Reproduction
The females give birth a couple of days after arriving on the beaches, and are then mated by the male whose territory she is in. Females nurse their pups for 6-12 months, although when food is scarce, they may nurse for up to three years. During this time, the mother undergoes a cycle of five days feeding out at sea and 1-2 days feeding her pup on the shore.

Infant mortality can be as high as 40 per cent in densely populated colonies, due to accidental separation from their mothers and aggression from adults.

Conservation status
South American fur seals are not considered to be threatened, and current population estimates are between 375,000 and 405,000 individuals. Commercial hunting of South American fur seals no longer occurs and was banned in Uruguay in 1991.