An abnormally early hibernation ending of the Red-bellied toad (Bombina bombina) (Discoglossidae, Anura) in the populations of the Medveditsa river valley (Saratov region)

Abstract

In the course of our long-term studies of the phenology of spawning migrations of anuran amphibians, which began in the Medveditsa river valley (near the Uritskoye village, Lysogorsky district, Saratov region) in 2009, an abnormally early end of the wintering period was recorded for the red-bellied toad (Bombina bombina) in the spring of 2020, namely, March 13. The anomaly was longer than a month in relation to the long-term average date of arrival of this species to its spawning grounds (April 18). The water temperature in the shallow waters of the spawning reservoir on this day was 10.2°С to a depth of 0.1 m, and 4.8°С at a depth of 0.5 m, and did not differ significantly from the average values typical for this phase of the B. bombina annual cycle in adjacent populations. The possible significance of this anomaly for the reproduction of local populations of B. bombina is discussed.