Myocastor coypus

Myocastor coypus
(Coypu)
(Swamp Beaver)

The Coypu is a large semi-aquatic rodent which is native to South America. It was introduced to the British Isles in 1929 when fur farms were set up in Sussex, Hampshire, Devon and Norfolk. The farms were sited mainly in lowland areas which are rich in rivers and streams. During the 1930's coypus escaped from captivity and despite repeated attempts to control them, they have adapted well to their new British habitat, breeding extremely successfully in the countryside of East Anglia. Today the Coypu, along with the Grey Squirrel, are a constant reminder of the folly of introducing foreign species into a new country without fully considering the consequences.

Superficially the Coypu and the Brown Rat are rather similar in appearance, hardly surprising as they are both rodents. But the blunt square shape of the coypu's muzzle and it's webbed feet clearly distinguish it, not to mention it's size. In fact it is one of the largest rodents in the world exceeded only by the South American Capybara (more about that later). The picture below highlights some of the differences:

Lets have a look at some biology:

Size: The Coypu is about 1 metre (39 inches) in length from the end of it's muzzle to the tip of it's round scaly tail. The tail alone accounts for about one third of it's length. It has short rounded ears, and small eyes that are set high on the head (like those of a beaver) so that it can see clearly whilst swimming.
Weight: Adult males weigh about 7kg (15.5lbs) though some have known to reach 9kgs with the female about 1kg lighter.
Colour: The coypu's fur is specially adapted to keep it warm and dry in winter. Long, coarse guard hairs conceal and protect the soft velvety under fur. This under fur, known as nutria (Spanish for otter) in the fur trade, is the reason why the coypu was bred in this country. The general colour of the coypu's guard hairs is dark reddish or yellowish brown, masking the slate grey nutria. The tip of its muzzle and chin have white hairs and whiskers.
Breeding Season: Breeding is continuous throughout the year.
Gestation Period: This lasts for four and a half months.
Number of litters/Year: Working out the sums...only two.
No of young/litter: This is usually 2 - 9 per litter.
Food: This animal eats plants, including; grasses, sedges, reeds, water parsnip, reed -mace and even water lilies.
Predators: The young are taken by foxes, stoats, dogs etc.
Distribution: East Anglia.