The European otter (Luther Luther), a small semi-aquatic mammal which lives along the rivers, sees its populations and its distribution area grow again in France while the species was threatened with disappearance in the 1980s. Thus, in 2009, the otter was only present on 20 % of the metropolitan territory. In 2023, it occupied 60 %, according to a study published in early July in the scientific journal Biological Conservation. The return of the otter is good news for biodiversity.
« The return of the otter can give several lessons for the preservation of biodiversity, in particular wild fauna. On the one hand, that ecosystems and species are resilient. Aquatic ecosystems are among the most vulnerable but they can quickly eat and allow the return of the species they house. Another teaching concerns the resilience of carnivores, when they are no longer hunted, they can make their feedback in a lot of spaces where hunting pressure exerts an obstacle to their boom “Consives Simon Lacombe. This scientist from the CNRS Functional & Ecology Center of the CNRS based in Montpellier is the main author of the study which confirms the trend to recolonize France by this little mammal.
The reconquest of a territory
The rapid expansion of the otter’s presence testifies ” of the recolonization of the territory by the otter from the basins where they remained in the Massif Central and on the Atlantic facade ”says Simon Lacombe. The researcher draws up ” a synthesis of a lot of knowledge on the otter in France ». To have populations of long-term viable otters, you must have an adapted habitat, that is to say watercourses with vegetable nourishing, rest and reproduction areas. The animal is a carnivore, it is also characterized by low dense populations. The authors of the study note that ” Over its recolonization, the otter shows a remarkable adaptability to various habitats, beyond its traditional bastions isolated from human and resource-rich facilities. »
A return of the otter observed thanks to the participatory sciences
The study was notably carried out thanks to more than 40,000 observations reported by naturalists and field associations. Simon Lacombe highlights their importance: ” It would be impossible to carry out national or even regional levels of such studies of monitoring the species without the contribution of participatory sciences ” He adds that ” These observations make it possible to draw up cards from the distribution area of the otter in France. We see that from the basins where they existed, the populations of otters are expanding towards Normandy, Burgundy Franche-Comté, Hérault, Gard and the Alps. In addition, there are connections between basins and populations ». These links between population basins allow the circulation of the species, the mixture of individuals and then the colonization of new areas.
A still vulnerable species
Despite the growth of its population, the otter remains fragile. Until the middle of the 20th century, she was the victim of hunting and poaching. The species has been protected since 1981. However, this small aquatic mammal remains threatened by the development of rivers and their pollution. “” The otter is always considered vulnerable in France ”recalls Simon Lacombe. The species is classified as almost worldwide worldwide according to the red list of the International Union for Nature Conservation (IUCN). However, the researcher specifies that the otter is almost everywhere ” The populations remain fragile at the local level ”. In France, ” The first cause of mortality of this predator is the collisions roads “, Of which he is” Difficult to measure the consequences on the species since the otter has a low population density on a given space ”.
In addition, so far, there remains in Europe and France, a strip of territory where the otter has not been replaced. “” It goes from the great east to the north, we do not know why. There is one or more factors that prevent the connection between the populations and make that in certain areas the recolonization of the otter is slower. The survival of isolated individuals does not necessarily mean a return of the species ”.
La otre, an animal with a strong capital sympathy, an asset for its preservation
Although difficult to observe during the day, the otter has a strong sympathy capital, according to Simon Lacombe. He reports that, during work on two distinct populations of otters living upstream and downstream from Montpellier, scientists were surprised to find clues to the Lotre’s passage in the city. They realized that ” The populations of otters were connected upstream and downstream of the Lez, the watercourse that crosses the city. The otters pass through a fish pass installed for the eels located in a very frequented place in the city ”.
« Large predators have an important role in the functioning and maintenance of ecosystems »
Finally, the current sympathy capital of the otter allows him to play a key role in awareness of both decision -makers and the general public to preserve biodiversity. But that has not always been the case, Simon Lacombe remembers that ” In the name of Umberto Eco’s rose, a novel whose intrigue takes place in the middle of the Middle Ages, the otter is listed among the animals associated with Satan. Today, collective representations have evolved, undoubtedly thanks to the good image of sea otters. ” Thus, Simon Lacombe gives as an example ” The national action plan in favor of the European otter which encourages any owner of land where a river passes to establish a haven of peace for the otter. The initiative works well. A haven of peace was even inaugurated last month in a school in the Montpellier agglomeration. “The rise and success of the Haps of Peace for otters everywhere in France testifies” in a new look “, According to the scientist who wishes to recall that” Large predators have an important role in the functioning and maintenance of ecosystems ”.
Julien Leprovost
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To go further
The European otter signs a spectacular return to France | CNRS Ecology & Environment
L’étude (en anglais) Range expansion and reconnection of historical populations in the Eurasian otter (Lutra lutra) in France: Insights from heterogeneous data and integrated species distribution modelling – ScienceDirect
The action plan for the otter in France pna_loutre_d_europe_2019-2028
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