Desman of the Pyrenees

The desman of the Pyrenees ( Galemys pyrenaicus ) is a Mammifère of the family of the talpidés which lives only in the the Pyrenees. It is a Insectivore semi-watery, alive near the torrents and of primarily night manners. It is called rat with trumpet because of the shape of muzzle.

It is one of the 79 animal species indexed like vulnerable in France by the World Conservation Monitoring Centers.

The desman of the Pyrenees lives in the torrents and lakes of the Franco-Spanish Pyrenees and the north of the Iberian peninsula. It is an animal discrete, difficult to observe and which fears the man little. He exclusively nourishes watery larvae sensitive to pollution (larvae of plécoptéres, trichoptéres and éphéméroptéres). For this reason he is regarded as a marker of his environment.

The desman resembles anatomically other animals the such rat, the mole or the shrew:

Of the rat ( Rattus norvegicus ), it has all the rear-axle unit: robust legs, squat thighs, a long tail being used to him to move easily in its medium of predilection, water;
Of the Mole ( Talpa europaea ), it has the part before body: legs griffues being used to dig the ground to arrange the burrow, centers education for its small and essential shelter against its different predatory;
Of the Shrew ( Sorex araneus ), it has a horn hyper developed being used to locate him the larvae of which it is nourished. This very sophisticated body is thus essential for him for its survival.

External description

The desman of the Pyrenees ( Galemys pyrenaicus ) is a Mammifère Insectivore of the family of the talpidé and subfamily of the desmaninés . It was described for the first time in 1811 by Etienne Geoffroy Saint-Hilaire starting from specimens which Mr. Derouay had addressed to him. It is in fact by chance that this animal was discovered.

Two S of the desman of the Pyrenees were distinguished, although this separation does not appear clearly:

Galemys pyrenaicus pyrenaicus
Galemys pyrenaicus rufulus

The first species would live exclusively in the Pyrenees, the second in the Iberian peninsula. The desman measurement approximately 25 cm, of which more half for the tail, and weighs from 50 to 60 grams (Geoffroy Saint-Hilaire, 1811).

With ground, its body is connected with a small ball of brown gray hairs, luisants, silver plated in lower part, with a fawn-coloured color in the pectoral area, contained in small packages giving the illusion of scales. These hairs guarantee a very great sealing thanks to a daily grooming with a substance secreted by an abdominal gland. The fur of the desman is designed perfectly for the subaqueous divings. It is made up of two layers of hairs: a layer internal, a sleeping bag puffing out and silky which are never wet, and an external layer - the earthenware jar - made long hairs unequal lengths, flattened like bands. Under water, this combination forms nothing any more but one quite smooth thickness enabling him to save the maximum of energy calorific thanks to a very great dynamism. Moreover, she imprisons an insulating layer of air which protects it from water and the cold. But this membrane of air makes it go back to surface like a cork stopper. The desman is thus obliged to be continuously moving to be able to drive out its preys, which involves an additional calorific expenditure…

Its tiny eyes are hidden under its hairs. The desman of the Pyrenees almost blind east, like the majority of the members of his family (Talpidae). It is hardly able to distinguish the shades from the light. Its ears, deprived of houses, are hidden under its fur. This auditive body is appeared as a simple perforation from 2 to 4 millimetres. Of this small ball exceeds, with the back, a robust tail at the beginning which is refined and ended in a small tuft of white hairs, and, with front, a hairy and mobile horn, broken up into two lobes.

This horn is the most important body of perception for the desman. It is using this one that it locates its preys under water and that it perceives its air and watery environment. Indeed, it is structured several tens of hairs - or bodies of Eimer - which are used to him to perceive its medium. With the manner of much of animal species having a horn, it would be possible that the proboscis of the desman him serf to be communicated with her congeneric, and in particular to intimidate the adversary at the time of the season of the loves. It is as in the elephants the result of the Coalescence of the nostrils and the upper lip, but also a very developed body which is worth with the desman the reputation of precursor of the radar and the night vision. In water, its privileged medium, its body becomes tapering, its legs before folded up against him, its legs postpones robust, webbed and isolated with 45 degrees, being used as paddles, are equipped with twenty pointed claws like needles and allow him to be clutched with the smooth rocks in spite of the force of the current. During its divings of a score of seconds each one, a valve closes its nostrils, proving thus that the evolution equipped it with the most powerful systems for an aquatic life. The desman of the Pyrenees moves quickly in water, in the search of its favorite preys. The body of Jacobson is most probably used to him “to feel” its preys under water. This body is on the level of the entry of the nasal fossae, which communicate with the mouth on the level of the palate of the desman, and has the shape of a long hair. Its sense of smell, very developed, enables to locate him the larvae to 5 cm under water. This very primitive body is the only sense of smell of fish and the Amphibians, but it is also that of the embryos of the mammals, without excluding the Man from it. The mammals lose it with the birth because they developed the direction with the use of the horns of the bottom of the nasal fossae.

Ethology

Activity - locomotor Acts - annual Migration

The activity of the desman of the Pyrenees is primarily night. However, there exists one period of strong diurnal activity between May and February, which corresponds to the season of reproduction of the individuals.

According to Stone (1987), the diurnal period, located after 12 noon, ranges between 10 and 30% length of the day. The night working life, as for it, occupies between 70 and 89% of the duration of the night. Analysis of the Nychthemeral graph watch which the activity of the desman is with its maximum around 4 p.m. for the day and with its minimum between 17 and 19 hours.

On the other hand, the diurnal activity, which is most intense, reaches its maximum enters 23 hours and 5 hours and its minimum as from 7 a.m. and this until the beginning of the second nycthémère.

It seems obvious that the desman privileges the night activity, at which time it is less likely to be perceived not its principal predatory (Loutre Lutra will lutra , Buse Butéo butéo , white Cigogne Ciconia ciconia , Brochet Esox lucius , Vison of America Mustela mink , Hermine Mustela herminea , Tawny owl Strix night aluco and another raptors).

Principal displacements of the desman are carried out in the aquatic environment during the research of food. Its stroke is very fast and the alternate movement of its posterior legs would give him a stroke zigzagante, if its tail, powerful, did not correct the variations of them. Its rare terrestrial displacements on the banks or a rock in the middle of the river, are only moments of rest devoted to its toilet (sealing of peeling, boxroom of the parasites…) or with the drying of its thick fur. With ground, the desman moves while claudiquant because of important size of its rear limbs.

However certain erratic individuals rove along a river. These specimens thus carry out long daily displacements and have consequently an energy need much more important than the individuals having a territory.

There exists, at these same erratic individuals, of the annual migrations which correspond in the search of partners during the seasons of reproduction.

The research of food

The desman of the Pyrenees locates its preys and detects them using the tactile and olfactive directions.

The directions of perception sit mainly in the horn of the desman. This one has three types of bodies: the Vibrisse S - allowing him to probe between the gravels of the bottom of the rivers - which contrary to appearances are not simple hairs (they are very advanced bodies in the field of the sensitivity), the Organe of Eimer, the kinds of long hairs detecting the least vibrations and the Organe of Jacobson which enables him “to feel water and to distinguish the odors there from its preys”. These bodies play a paramount role in the detection of the objects that it is in aquatic environment or air. A good precision of the localization of a prey in water seems to be reached only for one distance from 4 to 5 centimetres. The contact with the outside world is thus centralized at the end of the horn of the desman.

The desman of the Pyrenees is however unable to continue a prey which swims or which the current carries. It thus nourishes larvae fixed at rocks or insects too approaching close to water surface.

The desman of the Pyrenees emits small bubbles in a continuous way during its watery displacements. Besides this technique of localization seems very close to the echolocation of the preys, with the manner of much of other watery mammals, such as the Delphinidé S. Richard referred there in its thesis to be appeared on the desman of the Pyrenees.

The territory and lifestyle

The vital domain of the desman, its territory, seems to vary according to the place (abundance of food or not, population density…) and according to the sex of the individual. Each specimen knows its territory on the end of its horn. It engraved in its memory, the taste of its water, the odor of the banks, the circuit familiar and immutable of its labyrinth.

The desmans live either in couples, or only, wandering along a river. The occupied territory approximately for the linear females 250 meters, 450 meters for the males and 800 meters for the couples living on the same sector (Stone, 1987), along the brooks Oligotrophic S with average current at fort, with perfectly neutral water of any anthropic pollution. The members of the couples remain very distant one from the other. According to Richard, the female would occupy the medium of the territory and the male the periphery. The males and the females thus live in all the cases in different Terrier S.

The burrow is generally a cavity already dug on the bank by other species, or anfractuosity S between roots, between some stones coming from old constructions such as mills, dwellings… (We must note that we are there in the presence of the only pollution tolerated by the desman, these buildings being out of natural material). Many an experiment realized on desmans of the Pyrenees revealed that the burrow was composed of a long corridor of ten centimetres at the entry, ending in a papered room of Mousse, branches and of grass which is used as nest to the individuals.

It is interesting to note that frequent work concerning the installation of stone banks takes part in the progressive eradication of the desman which will desert all the zone where it will not be able to build its burrow;

Life expectancy

The males and the females have an life expectancy equivalent to three or four years. Indeed, of the animals marked at the time of research were recaptured to the maximum three years after their initial capture. Moreover, the study of the teeth of 87 animals proves that the longevity of the animal exceeds the three years (Richard, 1976).

It there forever have coupling when the animal is in captivity. Moreover, if the installation of enclosed sound does not correspond to its requirements, the desman will be let decay, which proves that its biotope should be respected as well as possible.

Reproduction and gestation - sexual Behavior

The period of reproduction is between May and February (even June) according to the temperature, of the climate and of altitude but it would seem that the females desmans have their heats permanently (Peyre, 1961). One will thus deduce from it that there does not exist strictly speaking of period of reproduction, but a peak of reproduction located in the time interval given previously. The desman waits the beautiful days to guarantee a rate of optimal survival to its offspring. The scientists think that the females can have three ranges per annum.

Being given the very short lifespan of the desmans, the individuals living in couples are faithful lasting all their life. The contacts between partners take place only at the time of reciprocal attractions of the male and the female (the female being larger than the male). Apart from these periods, any approach with less than five centimetres of two individuals (zone of perception of a desman) involves engagements irremediably often very violent one. Except thus these relatively rare combat, the males having a partner do not take part in agonistic acts to obtain the favors of one dulcinée. On the other hand, the erratic individuals being certainly polygamous, they could devote themselves to intimidating scenes followed by a parade to influence the female in its choice.

For the gestation period, the data on this point are absent. However, the desman pertaining to the family of the moles (Talpidae), one can estimate this duration at 30 days.

The setting with bottom takes place in the burrows described previously. The number of small per range is to the maximum of five. Indeed, we could find a female died with five embryos in the uterus, but the majority of the 55 females had 3-4 embryos (Peyre, 1961). The female has 8 udders: 2 pectoral, 2 abdominal and 4 inguinales. Sexual maturity is reached as of the season of reproduction according to the birth.

Ecology

The habitat

The habitat characteristic of the desman is composed of river, is said “oligotrophic” basic, average and high-altitude (defective rivers out of rock salt essential with the growth of the plants thus consisted of few algae).

Rivers that côtoie the desman are neutral of any anthropic pollution. Indeed, the larvae of which it is nourished are sensitive to the least variations of acidity, temperature, oxygenation and opacity of water. Consequently, the presence of the desman on a river shows the high-quality of water which it carts.

The populations of desmans alive on banks of the Lakes Ayous in the national park of the Western Pyrenees have a lifestyle and of particular habitat. Indeed, this whole of ten lakes is deeply cold 6 months in the year. The populations would thus take refuge in the underground rivers. Part of the desmans would be thus troglodyte (Combes and Salvayre, 1964).

The food mode

Following several stomachic content analyzes, observations carried out in captivity and with analyzes of deposit, the scientists could determine the food mode of the desman (Santamarina and Guitan, 1988; Bertrand, 1987,1988,1992).

The desman of the Pyrenees needs to introduce with the daily newspaper more than a third its weight in food (20 grams) to be in full form. The analysis of almost 1500 deposit realized by various scientists (Bertrand and Clergue, 1992), watch which its food mode is exclusively composed of benthic larvae of invertebrates, of three orders:

the Ephéméroptères
the Plécoptère S
the Trichoptère S

For a long time, it was believed that the desman of the Pyrenees was very sensitive to pollution resulting from the anthropic activities, but in fact, these are the larvae of which it is nourished which dies in the least disturbance of the current, the acidity or the oxygenation of water. It is thus important to determine the biotic indices of the watery environment, in particular the analysis of DBO5 (Biotic Demand for Oxygen), which corresponds to the oxygen rate consumed by the bacteria to break up the organic matter present in a water sample into 5 days, thus allowing to determine a relative purity of water.

The desman of the Pyrenees seems to privilege the larvae of Trichoptères, with raised energy value, which it exclusively drives out while plunging from 15 to 20 seconds in water. Moreover, these larvae are of more important size, therefore easier to capture and consequently great contribution of energy for a less effort.

Those will be consumed out of water, on the bank, in sitting position on the posterior legs. And it is using its horn, once again, that it will push them towards its mouth.

The fish consumption noticed forever during various work of analysis. The desman of the Pyrenees thus consumes, with rare exceptions, never of fish. This information enjoys certain importance when it is known that one of the causes of extermination of the desman is this reputation established by magazines of fishing in particular.

The magazines “Universe of living” of September 1985 and “the Pyrenees Magazine” of January 1989, shouldered by many television reports, published photographs of desmans introducing fish. These photographs were carried out with desmans alive in captivity and thus prove the nonsense of such a gesture; if one leaves an animal in a cage with like only food of fish, it is of oneself that this animal will devour fish rather than to die of hunger. But this food imposed by the man is not the reflection of the reality noted in nature.

Geographical distribution

The desman of the Pyrenees has a capacity of adaptation raised to altitude. One can find it starting from 15 meters above the sea level, on the level of Saint-EP-with-Bigorre in the basin of the Bubble (the Pyrenees Occidentales) and up to 2021 meters on the level of the Lakes Ayous located in the high valley of Ossau (Yrénées-Atlantiques);

In spite of a great diversity of adaptation on the altitudinal plan, there exist other dominating factors, in particular climatic causes.

; Limit related to the Pluviometry

The surface of distribution of the desman receives rates of annual precipitations higher than 1000 millimetres. The work carried out in a laboratory of CNRS with Moulis in Ariège (09) showed that the desman needed rather deep torrents (which bring much water) to open out (Bertrand, 1992). One could observed on the basin of the Salat (river), upstream of Saint-Bosoms (Bouigane River, Garbet), that the desman was present only on the affluents of left bank which traverse sectors whose pluviometry exceeds the 1500 annual millimetres, whereas it is completely absent from affluents of Right Bank which cross zones where annual precipitations do not exceed the 900 millimetres per annum.

; Limit related to the geological nature of the ground

The analysis of the nature of the basement starting from geological maps free-Iberian reveals us that a very great majority of the territory of the desman is limited only to one basement made up of metamorphic or igneous rocks (Granite, Syénite, Basalte, Marbre, Ardoise, Gneiss, Schistes…). According to the geological nature of crossed spaces, the rivers brew, in more or less large quantity, of the alluvia which support the growth of the algae micro and macroscopic. The desman not living, partly because of the larvae of which it is nourished and who are very sensitive to the disturbance environmental (in particular with the luminosity), that in water necks known as “Oligotrophe S”, i.e. nothing of all Phytobiologie, will survive with difficulty in mediums where the quantity of sediments is importance (indirect report/ratio).

Evaluation of the number of individuals

According to the geographical data most recent, going back to 1993, the desman would be present on 236 zones of the French Pyrenees (1 zone = approximately 71,5 square kilometers, is on a geographical map a rectangle of 0,1 X 0,1 rank on side); what represents a French zone of habitat of 1.687.400 hectares. This figure does not show reality. Indeed, the desman lives only on the rivers of these zones, which reduces its space of life appreciably.

According to the data of densities communicated by the national park of the Pyrenees (House of the national park of the Pyrenees with Gabas, magazine “Impressed”, n° 6) the number of individuals to the square kilometer would be about one only individual in an established zone.

By considering these identical data for all Pyrenees, the population of desmans would rise with less than 17.000 individuals on the French zone.

Certain people will be able to estimate that this population is sufficient to guarantee a rate of birth beyond the threshold of rejuvenation of the species, and thus to increase the number of specimens, but increasing death rate, the number of individuals is stabilized. One would not need only this “random” tendency is very not reversed in discredit of the desman of the Pyrenees. However, anthropic pollution reaching more and more often the last sanctuary of our small protected, the man must act to save it.

Future and protection of the species - conclusion

In 1811, Etienne Geoffroy Saint-Hilaire wrote in connection with his discovery that this strange animal was never above 1000 meters altitude. Today, one sees desmans with more than 2000 meters of altitude on the level of the Lakes Ayous. This alarming evolution shows us that the desman takes refuge more and more high to preserve various pollution; it is thus essential to protect this small animal very actively.

The future of the desman, emblematic species of the Pyrenees, both in France and in the Iberian peninsula, rests obviously primarily on the conservation and/or the restoration of its habitat.

The populations of desmans have seemed to be themselves stabilized for several years; the species seems in latent danger (red book of the threatened species, Beaufort, 1983). An information campaign seems to be essential in particular near the pisciculturists. Booklets on the desman could be given to each aquicultural exploitation, so that the professionals of the watery breeding clear them even the animal. These booklets will be able, in certain zones where the cohabitation man/desman seems very tended, to incite the pisciculturists to protect their basin with a fence in log from twenty centimetres height wood. This fence will prevent all desman from approaching too much close to the basin, the breeding will thus entirely be protected. The man is the worst predator of the desman. The pisciculturists kill, because of the popular beliefs, of the hundreds of desmans each year. He must thus invest himself in the safeguard of an inoffensive animal;

Another danger, also resulting from the technological explosion of these last decades, threatens the desman: they are water reserves. These reserves, indeed, vary the flow of the river, which involves a modification of the level, therefore consequently, a brutal modification of the temperature. Pollution, by wild discharges, also influences the watery ecosystem.

The variations of the current, depth, acidity and oxygen content irremediably kill the larvae of trichoptères and éphéméroptères, which constitutes mainly the food of the desman. This last is thus condemned to perish of hunger.

Water reserves

The law of June 29th, 1984 imposes the maintenance of a minimum flow on the level of water reserves. But this minimum flow is it sufficient? The Portuguese, Spanish and French scientists are not currently in measurement to be able to answer this question.

However, to check if the stoppings and other installations on river cause a real danger to the desman of the Pyrenees, of the analyzes biotic S of water were carried out upstream and downstream from the dam Bious-Artigues in the Western Pyrenees, like upstream and downstream from the paper mill of Saint-Bosoms in Ariège, source very polluting of Salat.

After the analysis under the optical microscope, one observes that there are as many microparticles essential with the food trichoptères and other larvae belonging to the food mode of the desman upstream that downstream from the stopping. The analysis of the DBO5 does not reveal any change between upstream and downstream of the stopping.

Water reserves thus do not present a danger to the food of the desman. On the other hand, we will note that the installation of industrial sites drawing the water of a river, such as paper mills, causes a real upheaval in the watery ecosystem, at the point even as the treatment carried out of waste water is not enough to restore original balance favorable to the desman. These industrial facilities must call into question the use which they make of water under penalty of unrelentingly reducing the surface of distribution of the desman.

Moreover, the brutal changes (running, temperature, acidity, oxygen content) which carry out reserves can be to him fatal. A rise of water floods its burrow and drowns it, and an obvious fall moves away it from its source of food: the lake. The installation of an artificial lake often strongly decreases the possibilities of refuge on the level of the banks. At the time of my study on the ground of February 2001, I had the curious one surprised to discover a brook in the place of the Lake Bious-Artiques. The management company of the stopping had emptied most of water reserve.

We are certain that the desman of the Pyrenees is present on banks of this lake (raised of deposit, many testimonys…). But how much desmans were they killed following this major disturbance of their environment?

The ecosystem should not of anything be disturbed but integrates the desman. This ecosystem is composed of elements known as “producing” (Phytoplancton…), of “primary education consumers” (Larvae, Zooplancton), of “secondary consumers” (desman, Otter) and décomposeurs. It is thus understood that only one disturbance at any place of this ecological cycle threatens the desman. The protection of an animal such as the desman must start with a respect of sound Biotope. But as we can see it in many sites, the industrial economy (in particular Hydroélectrique) premium on endemic environmental protection and of the animal species S. Pourtant, some simple measurements could protect the desman and thus generate a harmony between industries and nature. Thus, rather than to drain the stoppings in only once, I propose to release, when the need is essential, from minor amounts of water (for example a tenth of the contents of the lake), which would leave with the desman, like with the watery larvae, one period of sufficient adaptation to survive…

; Riprap of the banks

A study published in 1998 in the review of the National park of the Pyrenees (Impressed n° 6) shows us the evolution of the populations of desmans before and after the riprap of the banks of the Gave d' Aspe in the Vallée of Ossau. The modification of the banks of this river with in fact the practice of the riprap reduced the possibilities of zones of refuges for the species. Thus, on 25 places where the banks were modified and where historically the desman was present, only 6 are still occupied in 1998.

The desman of the Pyrenees uses for its burrow of the cavities formed by broken down walls, the roots of a tree… But riprap of the banks carried out in an artificial way reduced considerably the possibilities of refuge. Currently, this practice of embellishment of the shores proves to be essential in the Pyrenean communes and being given impossibility of stopping these harmful acts with the desman, I propose the distribution, on the rivers to weak access of the banks, of artificial burrows out of wooden, thirty centimetres length and a score of centimetres of width, papered inside natural foam and of a leafmold died, done everything for a total respect of the environment (use of any industrial product polluting, of any painting…). This resistant shelter is placed in easy places of access, very near to water. It was conceived starting from studies of true burrows of desman. Indeed, if it is known that the desman uses cavities already formed to build its nest, it carries out all the same a great number of modifications, such as the reduction in the diameter of the entry with branches, the installation of a room with dead sheets…

We must ensure the protection of the desman in the Pyrenees and the Iberian peninsula in order to ensure the conservation of the species, whose precariousness was recognized by the scientists. The reflections carried out by Spanish, Portuguese and French teams in the last few years abound in this direction.

Let us not forget only each day, its last habitat world is reduced… We must ourself act as responsible individual to ensure his protection because it did not reveal us all its secrecies.

It thus seems that an enlarging of the National park of the Pyrenees, as well on the Spanish side as French is obligatory. The regulation protecting the animals in the process of disappearance must be more strict. The creation of a “zone sanctuary”, ultimate refuge where no human being will be able to penetrate must be essential.

To protect its natural environment, it is to ensure its safeguard. But the desman is also the witness of a healthy and not polluted nature necessary for the man and the survival of our planet. It encourages us to reflect on a total management of Pyrenean, European, world water.

External bonds

Page and assessment of study on Desman
Site of presentation and conservation of Desman

category: Talpidé

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