The Population of the Common Grass Snake ( Linnaeus, 1758, Colubridae, Reptilia) in the City of Moscow. 2. Populational Morphological Characteristics and Features of the Ecology of the Grass Snake on the Shchukinsky Peninsula

In 2022–2025, morphological and ecological features of the population were studied on the Shchukinsky Peninsula in Moscow City, Russia. A total of 131 grass snakes were captured, marked and photographed, including 73 for the first time. Using the method of re-trapping the tagged sexually mature individuals based on the Petersen–Lincoln formula, the adult micropopulation was calculated at 83.9 ± 21.2 individuals. The total absolute abundance of the micropopulation, according to expert estimates and taking into account the young under the age of 1 year, was estimated at 80–100 individuals. The maximum relative abundance of grass snakes in optimal habitats did not exceed 1.5 individuals/100 m of coast. Using the correlation between total length and age, the dominance of 4-year old males with a total length of 63–74 cm and of 6–7-year old females with a length of 82–92 cm was established. One-fourth of the micropopulation consisted of injured individuals with partially amputated tails, among which females with a total length of more than 100 cm predominated. Based on the Student -test, the presence of sexual dimorphism of the grass snake in terms of body length (), tail index and the number of tail scales () was confirmed and statistically justified. In the recaptured individuals, both males and females, negative and positive tail allometry was established during ontogeny, respectively. Phenotypes of ventral surface coloration and the frequency of their occurrence were revealed and described. Using tagging and considering a sedentary lifestyle, the grass snakes were found to move 26–1600 m between captures. The movements of males during the activity season were on average 1.9 times higher than those of females. The velocity along the banks of the Moskva River in individuals was 105–123.5 m per hour in early May and October. Multiple captures of the same individuals in 2022–2025 made it possible to establish back and forth movements of males and females to some locations. The moving routes and distances traveled by males and females of the grass snake varied significantly, this being accounted for by the different strategies and motivations of the sexes during the mating season. Movements of the grass snake across the territory of the Shchukinsky Peninsula were regulated by the spatial and temporal strategy of using the area for reproduction and a successful existence of the micropopulation in conditions of high anthropogenic pressure and a short, six-month long period of activity. The patterns of movements of grass snakes show that they were characterized by the simplest diffusely homogeneous type of relationship with minimal interconnectedness of individuals. Obviously, this type of relationship allowed grass snakes most of the forage, protective and other resources of the territory to be used for successful life.