Like the flora, the French fauna has been profoundly modified by recent climate changes. In the Mousterian-Aurignacian era (last phase of the glacial period) large herds of mammoths, long-haired rhinos, horses, the musk ox, the Bos primigenius, the bison, the ibex (Capra ibex), the chamois (Rupicapra) lived), the marmot, the bear, the lion, the cave hyena; the reindeer was still rare. After the regression of the Wurmian glacier (from 10 to 20,000 years before our time), the animals of the cold steppe predominated, the reindeer and the saiga antelope, which reached the Pyrenees, the snow hare, the lemmings, the spermophiles, the jerboa, the wolverine, the polar fox. According to Estatelearning.com, the snowy owl and the black grouse lived on the soil of France, and the walrus frequented its coasts.
Subsequently, the climate, previously very humid (peat bog), became temperate and even warmer than in our days (age of the oak, 5000 years and about 2000 years before our time). The mammoth went extinct; some species retreated to northern Europe; others, remaining in place, adapted to the life of the forest: deer, elk, horse, wild boar, ox and some steppe animals (such as the hamster), the chamois, the Alpine ibex, the marmot, the white hare of the Alps (Lepus varronis), the bear, the marten and the lynx. Aquatic fauna was subjected to similar phenomena: all stenothermic species with discontinuous habitat can be considered as glacial residues, which cannot live except in cold water and reproduce in winter, such as whitefish of large alpine lakes and a multitude of Invertebrates.
On the other hand, an immigration coming from countries not subject to glaciation (South and South-West Atlantic coast) occurred in the periods of thermal optimum and in the sunny and dry regions it left residues with discontinuous distribution: a viverra, the genet, coming from Spain, it spread to western France to the west of the Loire and rose to the north, sometimes reaching as far as Normandy; the green lizard, (Lacerta viridis), which is encountered in the isolated stations of the Reno valley, like the praying mantis, reached the Norman region (it is very common in Jersey); the Pisan Helix, a Mediterranean form, reached Calais (1911) and Dunkerque (1922) through the coastal dunes.
Maritime domain. – France, with its three seas with different littoral aspects, the Mediterranean, the English Channel and the Atlantic, has the richest and most varied marine fauna in all of Europe. The Mediterranean fauna, clearly distinct from the other two, includes many particular species of Fish, Mollusks, Coelenterates, etc., which are, at least in part, residues from the Neogenic era; tuna (Orcynus thynnus), stenotermo of hot and salty water, sardine, anchovy, coral, sponges. Although the fauna of the Channel-Atlantic is all uniform, in the south-west, however, the presence of a certain number of Mediterranean forms (Lusitanian fauna) is noted. The main peaches are: that of cod similar to hake, in the Bay of Biscay; that of the sardine, a stenothermal fish of temperate waters, whose northern limit is Brittany; that of herring, in the east of the English Channel. In the coastal area, up to the limit of the continental plateau, fishing is done with nets for the sandy bottoms, and in the intertidal area, which remains uncovered at low tide, hand fishing and the farming of oysters and clams are done..
Brackish domain. – It includes: 1. the estuaries of the great watercourses; the coastal ponds of the coasts of Provence and Languedoc; the salt flats, the canals that lead into the sea. The fauna, rich in individuals and poor in species, is a mixture of marine species and very euryhaline freshwater species; some forms, such as the shrimp Palaemonetes varians, the isopod, Sphaeroma rugicauda, and the annelid, Nereis diversicolor, find their optimum therevital. 2. the continental salty ponds (Lorraine type), formed by salt flats or natural springs in communication with the Triassic deposits of rock salt. The rather poor fauna can only come from continuous fresh waters; however, there are beetles typical of maritime beaches, the saline Artemia of the salt pans, whose presence is not easy to explain.
Freshwater domain. – Out of a hundred European species of freshwater fish, France has 46 (not including potamotochi that enter rivers only to lay their eggs); their distribution is very different from that of terrestrial animals, since in the eastern and northern regions many species are observed which do not exist in the Garonne and Adour basins and which they probably received from Central Europe (Rhine and Danube basin); thus the sandra (Lucioperca sandra) only lives in the Saone and in the Doubs, the Zingel asper only lives in the Rhone and in the Saone; the Acerina cernua in the sec. XIX passed through the channels in several parts of the Seine and Loire basins, the Misgurnus fossilis, the crucian carp (Carassius carassius), the rodeo (Rhodeus amarus) do not go beyond the north-east or the Seine basin. We have already talked about glacial residues, such as, for example, whitefish. In some cases the influence of the marine population is noted; salmon, Salmo salar, of cold water, is missing in the Mediterranean and therefore also in the river basins that flow into that sea. The Blennius fluviatilis, the only freshwater representative of a littoral marine genus that is encountered in the south and in Corsica, evidently comes from the Mediterranean, as does the Atherina mochon, which went up the channel of the South to Toulouse. Four species of the United States have acclaimed: the bluegill,Eupomotis gibbosus, introduced in 1886 and which extends its area in the south-west and in the center, passing from one basin to another through the canals; the Micropterus salmoides, which does not stray from the surroundings of Redon (Brittany); l ‘ brown bullhead, imported to 1875 and which is now very common in slow-flowing waters and warm.