Současné rozšíření bobra evropského (Castor fiber) v západních a jižních Čechách [The current distribution of the beaver (Castor fiber) in southwestern Bohemia (Czech Republic)]
Petra Málková, Jaroslav Červený, Luděk Bufka
The beaver (Castor fiber) is an original mammalian species of Bohemia. Strong anthropic pressure resulted in the total extermination of this species in the area under study. Last occurrence is known from the Lužnice and Nežárka river basins (South Bohemia) in the middle of 18th century. In 1773, the artificial breeding of beavers was established in Červený Dvůr near Český Krumlov and some animals were released to the water sites in Třeboň region in 1804 and 1809. This reintroduction was very successful, but rapidly increasing distribution and population density resulted again in second extermination after 1870, because of the economic damages. In present, the re-occurrence of beavers is recorded in southwestern Bohemia. This colonisation is connected with the growing population in Bavaria. The number of 102 records from 1985 to 2000 are summarized in “Přehled lokalit nálezů” and Fig. 1. Occurrence of beavers is reported from 27 square grids, but permanent distribution is recorded only in 5 of them (18.5%) – Fig. 2. Most of the records (85 i. e. 83.3%) are reported from the altitudes between 350 m a. s. l. and 550 m a. s. l., but the lowest record (Radbuza river in Litice near Plzeň) lies in 315 m a. s. l. and the highest record (small pond near Modrava in the central part of the Šumava Mts.) lies in 985 m a. s. l. There are three areas of permanent occurrence: 1. Radbuza river with some side streams near Horšovský Týn, 2. Kateřinský potok brook between Diana and Hošťka with side streams and with Farský potok brook near Železná, 3. Kouba brook with some side streams near Všeruby. More other isolated findings are known, but the records from the Šumava Mts. are the most important. The estimated population size in the whole area of southwestern Bohemia does not exceed 15–25 individuals. The beavers were found to select different woody plants, preferring mainly Populus tremula, but also Salix sp., Alnus glutinosa or Sorbus aucuparia (only in the Šumava Mts.). Other tree species were used by beaver as food: Populus sp., Betula sp., Quercus robur, Fraxinus excelsior, Acer platanoides, Acer pseudoplatanus and also Picea abies. Also some agriculture plants (rape, maize, grass, clover) and herbs (Angelica sylvestris, Cirsium palustre, Filipendula ulmaria) were recorded in beaver diet.