The Pyrenean Desman
Captured Desman, Fédération Aude Claire
In the cold, clear streams of the higher altitudes of the Pyrenees there lives a strange little creature that is rarely seen; I have never seen it for certain, although perhaps I caught a glimpse of a dark swimming underwater shape one day after a storm; it could have been washed away from its normal habitat in the river’s torrential waters, and ended up near the Mill in our stream.
Almost as bizarre as the duck bill platypus (Fr. Ornithorynque), the Pyrenean Desman (Fr. Desman des Pyrénées) is cross between a mole (Fr. Taupe), a water rat (Fr. rat d’eau)– and a miniscule elephant (Fr. éléphant) as it has evolved the nose to be a very mobile and elongated trunk.
This little creature, weighing no more than 60 grams and only 25 centimetres long, including the rat-like tail, is endemic to the Pyrenees, the north Spanish mountains of the Asturias and the Picos Europa, and the north west coast of Portugal. The Iberian animals are classified as a sub-species.
A distant cousin of the mole, this is a semi- aquatic mammal, which was only discovered in 1811 in the Pyrenees. Much of its life remains a mystery, although attempts to study it in order to conserve its diminishing population are under way, financed at European level.
It is very difficult to study such a small and skittish animal, and as a last resort net traps have been fixed in suitable streams, although this is seldom done as it is very stressful for the desman. Generally it is found at 450 to 2000 metres altitude, where it was thought that they live solitary lives but the recent studies have begun to challenge this idea. In one case, four desmans were found in a stretch of water only 250 metres long in just 2 months of study. When trapped they may be fitted with a tiny transmitter. Last year I had signed up for several shifts up in the mountains manning the receiver in the hope of recapturing the same animal, but the transmitter no longer worked so the attempt had to be abandoned. To date seven specimens have been fitted with the transmitters.
Obviously the males and females meet up for mating, the female gives birth between February and July, having taken over a den on the river bank dug by another species or a crevice hidden under stones or tree roots. How many young are born is not known, nor is the life expectancy, but they can breed up to three times a year if conditions are right. By studying the teeth it is guessed that a lifespan of two to three years is normal.
It is known that the females with young will hold a territory of several hundred metres. An insectivore predator, eating much the same diet as dippers (Fr. Cingle plongeur), that is caddisfly larvae (Fr. Trichoptère) , and small crustaceans, and it needs to eat one third to half its body weight every day, and is active both at night and to a lesser extent during the day, with periods of rest. They do not hibernate, unlike other small mammals like hedgehogs (Fr. Hérisson) or bats (Fr. Chauves-souris).
Note the chain male gloves, protecting the scientists hands from the sharp claws and teeth!
The extraordinary ‘trunk’ is very flexible, capable of digging around under stones looking for the larvae and other prey that they eat. The whiskers play an important part in the hunt, and the nose contains the sensory organs known as Eimer’s organs which sense and gather information about the surroundings through the detection of stimuli. Eimer’s organs are among the most sensitive organs in the natural world.
The eyes are miniscule, and probably the desman is a very short sighted just like its cousin the mole, so functionally blind. Likewise the ears are totally invisible and probably they hear very little; they live, after all, in a noisy world of rushing water. Both the nostrils and the ears are sealed by a membrane when they dive under water.
There is another desman on the planet, the Russian desman. They are considerably larger, approximately 40 centimetres long with the tail, and weighing some 400 to 520 grams. They are known to often live in small groups of two to five animals, that are usually not related, and appear to have a complex (but also largely unstudied) communication and social system.
Here in the Aude they are vulnerable to predation by otters, and also introduced species like minks, or even cats and dogs. Its conservation status is endangered. Habitat destruction is another major cause of diminishing numbers, and as part of the conservation programme secondary streams are being re-opened on certain stretches of the Aude river and in other places adaptions have been made to increase the flow of water.
If you are a fisherman you might be very lucky and catch a glimpse of this busy but shy little beast. Most casual sightings are unfortunately corpses, or the small spiral droppings found deposited on suitable stones.
Once more the remote mountainous area near where I am lucky to live is wielding some of its’ store of secret and peculiar wildlife; thanks mainly to dedicated work by a handful of specialists, and, it should be said, public acceptance that taxes can be justifiably spent on helping such beasts to survive.
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