Friday, 12 February 2010

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

10 comments:

Leon and Sue Sims said...

Susan,
I bet it would be a surprise to see a Platypus.LOL, My favourite.
Why not introduce your readers to this great little creature?
Leon

Susan said...

Leon: Hmm, bit unlikely to see a platypus in the middle of Preuilly, but I did see a cockatiel flying around on the loose the other day and there are at least two thriving wallaby colonies on English moorland, so who knows...

Sweetpea in France said...

Have seen several live and dead coypus here and in other places in France as well as in our native land ... however a few years ago, a coypu's decapitated head on our lane was a bit scary!

Emm said...

The vole may be a pest, but it's an awfully cute one. I'm trying to figure out what's around him/her? Were you holding it somehow?

Leon and Sue Sims said...

We had a cockatiel a few years back. Chester was a wonderful little bird but became insanely infaturated with Sue, to the point he wouldn't let anyone come near her. Then Rosie and Gem (the cats) got jealous, not to mention me as Chester, Rosie and Gem were getting all the attention. Oh! I forgot to mention, there was also Murphy, our Irish Wolfhound but he loved me so I really didn't feel totally left out. Anyway, poor old Chester had to go as the cats kept salivating over him. He went to another home but died of a broken heart - Sue has never forgiven herself.
Leon

Susan said...

Sweetpea: yes, they are very common. Fortunately they have been eradicated from Britain now, but unfortunately they thrive in central lowland France because of all the riparian and wetland habitat available to them.

Emm: Voles aren't a pest at all, and they are a very cute little native species indeed. They are too small for their burrows to cause significant damage to riverbanks, unlike the much larger Musk Rat and Coypu, both introduced species that have become pests. The vole in the picture is a large young female code named Helen. She had been trapped as part of a wetland vole population survey and was being held in a gloved hand while her measurements were taken.

Merel said...

Staying between Lesigny and La Roche Posay for the week. On our way home from dinner last night and tonight stopped by the river bank in L.R.P. and saw something munching on the grass. At first we all thought it was an otter, then a beaver, or maybe a muskrat, but now we know it was a Coypu! Thanks for your thorough entry on European river mammals, and intrducing us to a new animal.

Susan said...

Merel: Glad you found it of use. Unfortunately it's almost always a coypu here.

Tim said...

Susan,
voles are far from being vegetarian...
they will eat slugs and snails as a regular part of their diet...
certainly, they are mainly vegetarian...
not omnivore...
but they do like a nice bit of meat from time to time.
Bank Voles, per example, will eat shell and flesh of a large land snail...
leaving only the spiral up the middle.

Missed this post first time round!!
Probably because we'd only just move in!!?

Tim said...

From the Notts Wildlife Trust:
"A water vole will consume approximately 80% of its body weight every day.
Water voles are generally herbivores, eating a wide range of vegetation, especially the lush stems and leaves of waterside plants.
They will also eat invertebrates."
So it could have been a water vole feeding spot.

But Muskrats are a possible suspect too... they are well known as omnivores.
And Coypu are known to eat mussels in their home range...

Finally...
it may not be a mammal at all...
Heron have been seen eating freshwater mussels and shoreline shellfish...
whilst they normally swallow prey whole, I personally can't imagine them doing that with a mussel...
they are more likely to smash it open and scoff the tasty bits...