Relations between Sexual Maturation of Overwintered Arvicola amphibius (Rodentia, Arvicolinae) Females and Their Physical Condition

In the spring period, between the last ten days of April and the second ten days of May, the dynamics of body weight, body condition, and cellular composition of vaginal contents in overwintered females from the natural population of water voles inhabiting the subtaiga zone of the Baraba Lowland were assessed. The onset of estrus in relation to the date of capture, as well as the body weight and physical condition of the captured animals, were analyzed. The results of multiple regression analysis showed that the onset of the physiological readiness of females for mating correlated significantly with their body condition. Sexually mature individuals had both body weight and body condition greater than immature ones.