Giant Otter

The giant otter is the longest member of the weasel family. It is dark chocolate-brown, looking almost black when wet, with very short, dense fur that water cannot penetrate. The tail is broad and flattened like a paddle (the genus name means wing-tail), all four feet are fully webbed, and the head is rounded with a short muzzle and a fully furred nose. Each animal carries its own pattern of white or cream blotches on the throat and chin, which researchers use to tell individuals apart (Wikipedia, general species account; Handbook of the Mammals of the World).

Unlike most otters it is highly social and strictly diurnal. Family groups of four to eight, built around a breeding pair and their young of several years, fish, travel and rest together, clearing riverside campsites and digging dens in the bank. Groups patrol and scent-mark their stretch of river and are very noisy, with distinct calls for alarm, aggression and contact. An adult may eat about 3kg of fish a day, taking small prey in the water and larger catches to shore. Young are born mostly in the dry season and stay with the family until the next litter arrives (Handbook of the Mammals of the World; Wikipedia, general species account).

Giant otters were once widespread in Bolivia, but hunting for their velvety pelts between the 1940s and 1970s wiped them from much of the country. A relatively healthy but small population of about 350 was estimated in 2002, and in 2001 Bolivia protected an area of wetlands larger than Switzerland that is also home to the species (Wikipedia, citing published surveys). On this guide it is a target species at Madidi, Noel Kempff Mercado, Barba Azul and the Beni savannas, and the Bolivian Pantanal.