Rats as big as cats? More likely a Coypu

IN THE Marais du Vigueirat, a nature reserve in the Camargue, I ran into an old acquaintance; a coypu emerged from a burrow, looked at me quizzically for a moment, sauntered down to a nearby pool and plunged in.

It was unusual meeting one during the heat of the day; coypus are more active at night and you generally see them early in the morning or at dusk. The encounter reminded me of John and Mary, two friends of mine who bought a tent a few years ago and headed off to France on a camping holiday. All went well for a couple of days. Then, early one morning, Mary emerged from the tent to find herself face to face with “the largest rat she had ever seen in her life.” She was panic-stricken. Camping was abandoned; the rest of the holiday was spent in hotels. Mary never slept in a tent again. But was the animal she had encountered actually a rat and did it pose any threat to her?

The terrifying monster could well have been my Camargue friend the coypu. The name is South American and roughly translates as ‘swamp beaver’. Compared to the brown rat, which weighs up to half a kilogram, this is a huge animal; a very large one can reach nine kilograms. It has a long rat-like tail, but the head is more like a beaver’s than a rat’s. Its ears are tiny and it has conspicuous whiskers. The little eyes are set high in the head so that it can see when swimming. Its teats are also high up so that babies, riding on its back, can suckle while their mother swims. To me, the Coypu seems a cuddly endearing creature and not at all fearsome.

Nor had Mary the slightest reason to be alarmed. Coypus are entirely harmless. Unlike rats, they don’t spread infection to humans, although they can get foot-and-mouth disease. Rats are scavengers which invade dumps and sewage pipes, but coypus are squeaky-clean vegetarians; they won’t raid the food-box in your tent while you are out.

Coypus are not native to France. They were introduced from Argentina by fur farmers in the 1920s. Inevitably, some of the prisoners escaped and set up shop in the wild. They are ferocious diggers, burrowing into dykes and under paths. Their underground passages can be up to six metres long and the holes which they make in banks can cause flooding.

Their presence in the Camargue is very obvious from the holes and subsidence to be found along paths in some of the reserves. Nor are conservationists entirely happy with their presence. Coypus are such voracious feeders that they can alter the structure of a marsh and even eliminate some species of plants. Poisoning, trapping and shooting have failed to eradicate the coypu in France. Similar measures were more successful in Britain. A population which had become established in East Anglia was exterminated in 1989.

But Mary’s encounter may not have been with a coypu. The muskrat has a much wider distribution in France than the coypu and it could be the beast which so terrorised her on that fateful morning. It’s much smaller than the coypu, but, weighing up to 1.8kg, the muskrat is still three times the size of a brown rat. It gets its name from a musky odour emitted by the male.

This is an attractive animal and I personally can’t understand why anybody would be frightened of one. It resembles a very small beaver but without the beaver’s big paddle tail. The muskrat’s long tail is unusual, being about three times as deep as it is high. Like beavers, muskrats slap the water with their tail as a warning signal when they are alarmed. They are vegetarians, although they will eat the occasional fish. Great underwater swimmers, they can remain submerged for up to 15 minutes.

Like beavers, muskrats have architectural skills. They build lodges out of grass and reeds. These are enclosed structures up to a metre deep with a storage area and separate rooms for the male and female. Sleeping apart is a wise precaution as muskrats have short tempers and quarrel constantly among themselves. They can, if provoked, even attack people, but Mary had nothing to fear.

Muskrats were brought to Russia from North America 100 years ago. Escapees established colonies in the wild and soon spread to Finland and Sweden. Following other introductions, muskrats colonised much of northern and central Europe. They are not a health threat, but like coypus, they make extensive burrows in river banks and ditches and are a nuisance to farmers. They were once a problem in Ireland. Muskrat farms were established in Clare and Tipperary in 1927. It was not long before animals escaped and local banks and dykes were being damaged. The invasion was deemed such a threat that a Muskrat Act was passed by the Dáil in 1933. By May 1934, trappers had killed 487 muskrats and the species was declared extinct here. The episode was documented by T Garvey in a paper entitled The Muskrat in Saorstát Éireann, which was published be the Department of Agriculture in 1935.

Muskrats and coypus are fairly easy to see, so the next time you pitch your tent in France, and you happen to be near water, keep an eye out for these extraordinary rodents.