Variations in fur coloration of European bank vole (Clerthrionomys glareolus Schreber) from Upper Volga and adjacent areas

Trends and possible causes of variations in fur coloration of wintered European Bank Voles in Tver region are analyzed. Two color forms have been revealed: grayish and pronouncedly red. The cline variation is ruled out for the color forms of the studied area. The taxonomic significance of populational variations is discussed. The connection of coloration with annual precipitation and winter temperatures is proposed.