CROATIAN FAUNA 2003 - RODENTS - BRAVER (CASTOR FIBER L.)

The stamps have been issued in 20-stamp sheets, and there are also the commemorative First Day Cover (FDC), three maximum cards and combined booklet (6 x 2,30 HRK, 2 x 2,80 HRK and 2 x 3,50 HRK). Rodents, the order that includes the dormouse, squirrel and beaver, are spread out world-wide. Half of the existing mammals are rodents among whom we distinguish 2821 species. Their name is derived from their upper incisors that are significantly bigger than the other teeth in the jaws as they grow incessantly. Rodents live in all regions where vegetation is spread out. The particular places of their most frequent dwelling are different: they can be found on trees, under the surface of the earth, in water, in subterranean holes, in bushes and in open fields. Considering their interrelation, they may live in couples, in families or in large groups. Rodents are chiefly herbivore and feed on roots, tree bark, leaves, flowers and fruit. Some species feed on food of animal origin, which classifies them under omnivore. It is characteristic, too, that particular rodent species hord supplies of food into some underground storage to secure their needs in unfavourable seasons. Individual species represent (or used to represent) significant economic species, primarily on account of their precious fur (beaver, coypu, musk-rat), but also for its meat (dormouse), and this is the reason they are also being raised on farms. Many rodents represent the most harmful and dangerous of man’s enemies. On account of their extreme natural reproduction and taking into account the food they feed on, they often cause incalculable damage to the crop and in households. They are also transmitters of numerous infectious diseases, which poses exceptional danger for man, particularly in densely populated places or regions. Man’s perpetual fight against rodents and the great number of their natural enemies, as well as various diseases attacking rodents, all these factors keep their natural balance, otherwise they would flood the Earth. On the other hand, certain rodent species have been reduced to a rather small number, which demands their strict protection and activities that would bring about the preservation of the species from extinction. Among the species that demand our protection are the dormouse, squirrel and beaver, and this is the reason that they find a deserving place on postage stamps. Beaver (Castor fiber L.) The beaver is a semiaquatic animal species and the biggest rodent of the Northern Hemisphere. It is massive and thickset in build, an excellent swimmer and diver. These features are made possible by the build of its body. The body comes up to 1 m in length, the height of the rump is up to 30 cm, and the tail is wide and flattened, some 30 cm long. The individual adult animal weighs from 20 to 30 kilos. The colour of the hairs is dark reddish-brown to grayish, and on the stomach it gets lighter. The beaver is a typical monogamous animal. It matures sexually when it is 2 and a half years old, when young beavers leave their parents and found a new family. It mates from January to March and the mating itself takes place in the water. The gravidity lasts 105 days on the average, and the young litter from April to June. There is one generation a year and the female has from one to five young. The beaver lives in riverbeds and water surfaces covered with a rich swamp vegetation of herbaceous and woody plant species. The basic condition of a beaver’s habitat is constant and abundantly deep water (minimum 30 cm). If it dwells in a smaller riverbed that sometimes becomes too shallow, the beaver will build a dam on it to ensure the sufficient level of water and protect the entrance to its abode. The beaver is exclusively herbivore: in summer it feeds on juicy herbaceous plants that can be found in water or close by, on the river bank. There are some 300 herbaceous and woody plant species that the beaver feeds on. The European beaver used to dwell in all suitable riverbeds and water surfaces, from the north to the south of the European land, but at the beginning of the 20th century it survived only on four localities: in southern Norway, on the river Elbe in Germany and Poland, on the lower flow of the river Rhone in France, and in Russia. Owing to the activities to bring the beaver back to its former habitats all over Europe, starting with the new millennium the beaver has spread out again on a wider area and presently theire numerical strength is favourable. According to the data for the year 2000, the beaver population in Europe is somewhere in the region between 600,000 to 650,000 beavers. In Croatia the beaver became extinct at the end of the 19th century, and it was brought back to Croatia between 1996 and 1998 within the framework of the project “The beaver in Croatia”.