Regularities of the changes of calendar dates of the start, end and duration of Pelobates fuscus wintering in the Medveditsa river valley (Lysogorsky district, Saratov region) within the period from 1892 until 2014 are considered. A reduction of the wintering duration by 7 days (on the average) over the last 120 years is shown, due to a shift of the start wintering date to a later date and that of the end wintering date to an earlier date.