Tuesday, 15 April 2014

On the trail of Otters and Beavers in La Vienne

20 years or so ago it would have been impossible to find an Otter or Beaver in any of the rivers and waterways of the Vienne department of France, in fact the Otter was almost pushed to extinction in France and was only to be found in the Atlantic regions and the Massif Central by the 1980’s . Since then there has been a steady improvement with a continuous re-colonisation inland towards the east following the main river systems and their tributaries. In the Vienne department we have the rivers Charente which enters the sea near Rochefort and the Vienne which is a tributary of the river Loire. Both of these rivers also have numerous tributaries notably in the Vienne these are the Clain and the Gartempe which again have their tributaries.

The situation with Beavers is somewhat different following their extinction in most of France with reintroduction being required in many places.

The only river in Poitou Charentes where a reintroduction was attempted was the Creuse in Vienne where 4 beavers were released during 1970-1973 and this failed but this wasn’t the end for our region. During the period 1974-1976 13 beavers were released in the river Loir in Loir-et-Cher and during 1994-1996 another 13 were released in the river Loir in Loir both being successful. From the river Loir the Beavers have bred and slowly increased their range and are now present for us in the rivers Vienne, Creuse, Gartempe, Anglin, Salleron, Clain, Thouet, Argenton and la Dive du Nord.

One of the many tasks undertaken by the recognised Nature Associations along with the ONCFS (Office National de la Chasse et de la Faune Sauvage) is to research and monitor the presence and range expansion of both species and in the Vienne there are several days of research dedicated to this in most years by Vienne Nature along with a small number of volunteers. This requires the relatively simple practice of seeking out signs of their respective activity.

For European Beaver this is dam creation, small tree felling and small gnawed or stripped pieces of branch with their distinctive chiseling patterns.

For Otters it is spraints, (otter excrement), footprints and remains of prey, crayfish claws, fish heads and frogs/toads that have had their insides eaten. Great care needs to be taken with the remains of prey that could result from other activity, anglers in the case of fish and crayfish remains and also Polecat, (Poutois), for Crayfish and frog and toad remains.  Generally frog and toad remains, (known as “carnage”), should not be taken as concrete proof but are a good indication when spraints have also been found within a few kilometres.

With this in mind I set out with Miguel Gailledrat of Vienne Nature the other week for a day on the Boivre a small river that rises in Vasles, Deux-Sevres and enters the river Clain in Poitiers. Its name La Boivre is thought to be derived from the ancient French word Bièvre for Beaver and is today also called Rivière aux castors or “beaver river” although there is no evidence that Beavers were ever here and it wasn't Beavers we were looking for in this river but Otters although it's quite probable that they will colonise the Boivre in time.

I should mention that although the principle purpose was to look for signs of otters we would also record any signs of Coypu, Southern Water Vole and any freshwater clams or mussels and indeed anything else noteworthy but not plants although I’ve included a few photos! The idea is to look at all the bridges and ideally look for 150 metres or more either side of the river on both sides of the bridge if this is possible which unfortunately it often isn’t. When only one side of the river is accessible the use of field glasses may assist in viewing any flat surfaces on the opposite bank.

Click images to enlarge.

The Boivre is the last river in the Vienne dapartement where no signs of otters have been recorded and we were hopeful that we could change that and complete the map and remarkably the very first bridge visited produced spraints on the concrete re-enforcements on both sides of the river – what a great start to the day!

The rest of the day continued with some success with more spraints at different locations, one really fresh! Also found in three locations were toad and frog carcasses, plenty of traces of wild boar and roe deer, coypu excrement and some freshwater mussel, (Potomida littoralis), but for me another important and interesting discovery was some Southern water vole, (Arvicola sapidus), excrement on some rocks by a bridge, a protected species which is being recorded Nationally.

The situation with the Beaver in the river Clain is that traces of activity have been found in the northern part of Poitiers and it’s hoped that they will move through the city and out to the south.

Otter in France

European Beaver in France

Southern Water Vole in France