Spatial distribution and populational dynamics of Eurasian Beaver (Castor fiber Linnaeus, 1758) in the Orenburg State Nature Preserve

The Eurasian Beaver (Castor fiber Linnaeus, 1758) was widely distributed in the past across the mixed and broadleaf Eurasian forests, including the major portion of the Ural River basin. By the mid19th century, however, it had been completely exterminated here. In the mid20th century, due to the reacclimatization efforts, it resettled most of its range in the middle section of the Ural River. By the end of the 20th century, it occupied most oxbow lakes with suitable habitats and began to populate the suboptimal water habitats including the sparsely forested headwaters of the left bank tributaries of the Ural River within the Orenburg State Nature Reserve: Aytuarka, Zharyk creek, Tyshkak creek (Aytuarskaya Steppe); Tuzlukkol creek, Urtaburtya, Mueldy (Burtinskaya Steppe); Urtaburtya, Burtya, Karagach (Preduralskaya Steppe). Based on the field records made by reserve rangers, we reconstructed the beaver settling process in the cluster sites of the Orenburg Reserve and its buffer area. The most favorable conditions have developed in the protected area of the Aytuar Steppe Site, where beavers inhabited streams, floodplain lakes and tributaries of the Ural River. Only two or three permanent settlements were found in the other two sites, and from here some individuals migrated periodically in favorable years along less suitable stream systems and formed temporary settlements.