Some thermobiological features of the grass snake Natrix natrix (Linnaeus, 1758) and the common European adder Vipera berus (Linnaeus, 1758) in cohabitation in the Kama Cis-Urals

The paper presents data on the body temperature, surface temperature of the selected substrate, and ground air temperature for the common grass snake Natrix natrix (Linnaeus, 1758) and the common European adder Vipera berus (Linnaeus, 1758) during syntopy in the Kama Cis-Urals. Thermal preferences and modal classes have been determined for both species according to three thermobiological parameters, and a detailed statistical analysis of the median modal classes has been carried out which provides a more accurate analysis of the differences in temperature preferences between the species. It was revealed that the average temperatures of the body and the environment are significantly higher for the common European adder. These features may be associated with the choice of specific conditions within the general biotope, since the common European adder is more often found in open, well-heated areas.