Nutria (Myocaster coypus, Molina, 1782)
Origin: Subtropical and temperate South America
Size: 40 to 60 cm (body), 30 to 45 cm (tail)
The Nutria is a large rodent, rat-like. The pelage is brown-grey-yellowish with a yellow spot under the ear, the belly is white with a cylindrical tail; the incisors are prominent and bright-orange-yellow and it has a white muzzle. The hairs are soft and dense adapted to semi-aquatic life and between the fingers it has interdigital membranes for swimming. The tail is shorter than the body length and the adults can reach 14 to 16 kg, although usually average 4 to 7 kg. Females and males are alike in colour and size.
This species is native to South America, south of 23° latitude (includes Argentina, Bolivia, Southern Brazil, Chile, Paraguay and Uruguay). Generally are found near the water, in reed beds, swamps, marshes and also in rivers, streams, ponds, lakes and brackish waters, rarely are observed over 100 metres from the water. The diet is mainly herbivorous, feeding of wetland plants and crops, but occasionally of fresh water mussels. Breeding occurs through the year and sexual maturity its reach at 3 to 10 months old. Severe winter cold reduces reproductive success and adult survival. The Nutria is more active at dusk and lives in groups.
Economically, the Nutria are valued as a source of fur and was introduced in many countries for fur exploitation; due to escapes and release from fur farms this species is now naturalized in North America, Europe and Asia. This species is considered one of the 100 world’s worst invaders; they build burrows which penetrate and damage river banks, dykes and irrigation facilities, it’s feeding methods lead to the destruction of large areas of reed swamp, which has impact on plants, insects, birds and fish species. This species was not yet observed in Portugal although is considered invasive in many countries in Europe including Ireland, Italy, France and Spain.