Aquatic Mammals on the River Claise

A couple of weeks ago a friend told me he had been walking along the river bank in Preuilly and he had seen a dead animal about the size of a cat floating in the river. He thought it might have been a beaver and suggested I go down and have a look. I went down a few days later, not really expecting to see anything after that time had elapsed, and indeed, the dead creature wasn't there. I thought it was most probably a coypu, as these are very common, and classified as vermin, so it would not be unlikely to see a dead one, perhaps poisoned.

A Unionidae freshwater mussel shell.
This one is 13cm across, but they can grow to twice that size.

However, I was intrigued to see a dozen or so fresh water mussel shells up on the bank. Maybe the deceased hadn't been a coypu after all. Coypu are strictly vegetarian, but their smaller cousin the Musk Rat, also a common, introduced, nuisance species, are particularly partial to a nice juicy moule d'eau douce. Otters will eat them too. Does Preuilly have otters? It almost certainly has Musk Rats and it's possible that there are otters in the Claise, but they will be much rarer.

Vole holes.

Close to the mussel shells was a group of vole holes in the grassy bank. I don't know what species. Not Water Voles - I caught a glimpse of a little face peeking out of it's hole, and it was not big enough for a Water Vole. Probably a Common Vole. Anyway, it wasn't voles eating the mussels, as they are vegetarian too.

Freshwater mussel shells scattered about on the riverbank.

It wasn't beavers either. Signs of beaver activity on the Claise at le Grand Pressigny was reported recently in the newspaper, but once again - they're vegetarian.

It's worth keeping an eye out for any of these aquatic mammals, especially early in the morning or in the evening at dusk. Some species can be quite hard to tell apart until you've had some practice, but even the nuisibles are fun to watch.

Here's a quick overview so you know what to look out for, in order of size:

Northern Water Vole

Northern Water Vole Arvicola terrestris (Campagnol terrestre in French): The biggest common vole species in France, a rodent that lives on the banks of slow flowing rivers rich in vegetation. Ratty from the Wind in the Willows is this species. About 20cm long excluding tail, which is about half the length of the body and thin.

Musk Rat Ondatra zibethicus (Rat musqué in French): Native to North America, they were introduced to Europe by the fur industry. This rodent lives along slow flowing watercourses, richly vegetated étangs (fishing lakes) and marshes. About 30cm long excluding tail, which is nearly as long as the body and keeled (thicker from top to bottom than from side to side). A large Musk Rat and a small Coypu can be very difficult to tell apart.

A Coypu swims across an étang in the Brenne.

Coypu Myocastor coypus (Ragondin in French): A large rodent native to South America which was introduced to Europe by the fur industry. A herbivore, it has few predators in France and can be a problem in crops as well as causing damage to river banks with its burrowing. About 35-65cm long excluding tail, which is about two thirds the body length and cylindrical. Coypus have white whiskers and a grizzled muzzle. The muzzle colour and tail shape distinguish coypus from Musk Rats and Beavers.

European Otter Lutra lutra (Loutre d'Europe in French): The otter very nearly became extinct in France, a victim of hunting and pollution in rivers and wetlands. In the last 15 years its numbers have increased, but it will never occupy all the territory it once did, and sadly, the Touraine is not one of its modern strongholds. About 60-90cm excluding tail, which is about half as long as the body.

European Beaver Castor fiber (Castor d'Erasie in French): This species very nearly became extinct in France in the 20th century, due to hunting for the fur trade and the destruction of its wetland habitats. A successful reintroduction programme has meant it is now well established in the Loire Valley. It is the biggest rodent in Europe. An adult beaver can be 1.4m long including tail and weigh 35kg. The flat tail is the best way of recognising this species. Where they are present they are most easily seen on summer evenings. They are remarkable wood cutters, capable of felling an 8cm diameter tree in 5 minutes.

Susan