Changes in the Northern Boundary of the Eurasian Beaver ( Castor fiber Linnaeus, 1758, Rodentia, Mammalia) Range on the Yamal Peninsula (Western Siberia) during the Holocene

Fragments of birch ( Betula pubescens ssp. tortuosa (Ledeb.) Nyman) and spruce ( Picea obovata Ledeb.) trunks with traces of gnawing by the Eurasian beaver ( Castor fiber Linnaeus, 1758) were found in the modern tundra zone on the Yamal Peninsula. Tree fragments were dated by the radiocarbon and tree-ring methods. At the beginning of the Middle Holocene, the northern boundary of the beaver’s range was at 68°39′ N. At the end of the Middle Holocene, it was at 67°33′ N. At the beginning of the Late Holocene, it was 66°33′ N. Changes of the boundary followed the formation of closed forests on the Yamal Peninsula. As they became established, the beaver’s range moved northward. As the woody vegetation boundary retreated to the south, the beaver’s range also retreated to the south. Stabilization of the northern boundary of the beaver range took place at the beginning of the Subatlantic climatic stage of the Late Holocene following the stabilization of the southern boundary of the forest–tundra zone.