CoypuMyocastor coypusWhere and when to see them

The coypu, also called the nutria, is a large semiaquatic rodent native to southern South America. Introduced to Europe largely through fur farming, it has established wild populations in many waterways. It occurs in the Rhine, Saône and Seine river systems, although its local abundance varies. Its grazing and burrowing can damage wetland vegetation and banks, and it is listed as an invasive alien species of Union concern in the European Union.

Size

Head and body length 40–65 cm; tail 30–45 cm.

Weight

Usually 4–9 kg.

Lifespan

Typically up to 6 years in the wild; up to about 10 years in captivity.

Status

Least Concern (IUCN).

Coypus are strong swimmers that use their partly webbed hind feet for propulsion. They are often most active around dusk and at night, but daytime feeding is also common where disturbance is low. They usually stay close to water and retreat into it when alarmed. Social groups commonly include females and their young, while some males range more widely. Coypus excavate burrows in banks and may also rest on platforms made from vegetation. They groom regularly to maintain their dense coat. Breeding can occur throughout the year where conditions are favourable, although cold weather can reduce survival and reproductive success.

• Coypu incisors have iron-rich enamel that gives their front surfaces an orange colour.
• Females have teats high on their sides, allowing young to nurse while the mother is in water.
• Young are born furred, with their eyes open, and can swim soon after birth.
• The name nutria is widely used for the coypu, although nutria means otter in Spanish.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

Coypus inhabit freshwater wetlands, including rivers, canals, ponds, lakes and marshes. They favour slow-moving or still water with abundant aquatic plants and accessible banks. Along the Rhine, Saône and Seine, sheltered side channels, backwaters and vegetated margins can provide suitable habitat. They also occupy modified waterways near farmland and settlements. Prolonged freezing conditions can limit populations by restricting access to food and water and causing cold-related injuries.

Coypus are primarily herbivorous, feeding on aquatic and bankside plants. They eat stems, leaves, roots and rhizomes, often pulling up vegetation while foraging. They may also graze grasses or feed on crops beside waterways. Animal material, such as small freshwater invertebrates, is occasionally eaten but forms a minor part of their diet.

Common name

Coypu

Scientific name

Myocastor coypus

Animal group

Mammals

Size

Head and body length 40–65 cm; tail 30–45 cm.

Weight

Usually 4–9 kg.

Lifespan

Typically up to 6 years in the wild; up to about 10 years in captivity.

Status

Least Concern (IUCN).

Identification

Look for a stocky brown rodent with a blunt muzzle, conspicuous pale whiskers and small, rounded ears. The long, sparsely haired tail is cylindrical rather than flattened like a beaver's. Bright orange incisors may be visible when the animal feeds or grooms. Coypus are generally larger and more heavily built than muskrats, whose tails are flattened from side to side.