Reproductive biology of water snakes (Serpentes, Colubridae, Natrix) in Samara region

Females of dice snake attain a sexual maturity at larger sizes than females of grass snake. Both species laying eggs later in northern regions than in south regions: this tendency expressed better for grass snakes. Grass snakes from northern regions have larger fertility than they have in southern regions. Geographical differences of eggs sizes are not revealed. Neonates of both species in northern regions have a larger sizes and mass in average that the same in southern regions. Correlation dependences between female linear size and quantity of eggs in clutch as well as sizes of neonate are revealed.