The Giant River Otter lives in the Peruvian tropical rainforest of
South America. Giant River Otters live in lakes and slow-moving rivers
in forested areas. The Giant Otter population once was widespread from
Venezuela to northern Argentina. Today only isolated pockets of otters,
estimated 2,000 to 5,000, are left due to fur hunting and habitat destruction.
Giant Otters are carnivorous mammals. They are related to weasels,
badgers, porcupines, polecats, and minks. Out of all of the members
of their family, Otters are the species best adapted to aquatic life.
Generally, they live in families of five to eight. They spend most of
their time in the water and find most of their food there. Giant Otters
hunt during the day and sleep at night. Their diet consists almost exclusively
of fish, and is much less diverse then other otters.
The outer fur is thick, dark, and waterproof. The inner coat includes
an insulating layer of air, and stays dry even under water. The giant
otter can grow up to 6.5 feet long and 75 lbs. Adapted with webbed feet,
a strong, flattened tail, and a sleek form for moving in water, they
look funny as they waddle on land. An amazing thing about their whiskers,
which are called "vibrissae", is that they can use them to detect changes
in current and water pressure. This helps when they are searching for
fish and other prey because they can detect the prey's movement. These
Giant Otters can also dive for several minutes at a time. You might
hear a giant otter before you see him, as he playfully lets out loud
whistles, screams, and hums.
Another special feature of the Giant Otter is their highly developed
social behavior. They live within groups of up to 10 individuals, who
hunt, sleep, and play together. The groups are composed of a parent
couple with their young of several years. A group occupies a confined
territory, and the territories of different groups do not overlap. The
Spanish name is "Lobo Del Rio" or "river wolf" having to do with their
social behavior. There is also no other otter species in which males
and females live together.
After a pregnancy of 65-72 days in the dry season between May and
September, otter females give birth to one to four cubs. Usually, only
the dominant female of a group reproduces. All group members, however,
help with raising the young. During the first two months of their lives,
the cubs stay inside the den. Otter groups are noticeably more alert
and careful than usual when caring for their young. Today we also know
that females under stress stop producing milk so that the young starve
to death within a couple of days if the mother is constantly disturbed.
By the age of two or three years the Giant Otters typically go on and
occupy their own stable home range where they stay year round. A Giant
Otter home range includes at least one lake, usually several smaller
creeks, and part of a river. The oldest documented life span was 8 years
for free-ranging Giant Otters and 14 years for ones in captivity.