The grass snake is extremely difficult to observe as it is a fast-moving and wary species (2). Because it derives its body warmth from the environment, the grass snake has to bask in the sun after emerging in the morning in order to reach high enough body temperatures to be able to function efficiently and digest its prey (3). During winter, temperatures are too low, and the grass snake will find frost-free places such as deep leaf litter or rock piles in which to hibernate between October and March or April (2).
Courtship and mating takes place from March to June. The male grass snake will curl its body around a receptive female, rubbing the female with his head and wrapping his tail closely around the females body to allow copulation to take place. The female then departs and searches for a nesting site (2). The grass snake is Britain's only egg laying snake (3); eggs are laid in compost or manure heaps where the rotting vegetation creates warm conditions (2). Development of the leathery white eggs depends on the temperature, but hatching usually occurs six to eight weeks after egg-laying. The hatchling snakes escape from the eggs by chipping at the shell with an egg tooth, which is lost shortly after hatching. The male grass snake becomes mature at 3 years of age, but females do not begin to breed until they reach their fourth or fifth year. After reaching maturity, males shed their skin twice a year, whereas females slough their skin once a year just before egg-laying. The grass snake can live for up to 15 years (2).
The grass snake is an active predator of frogs, toads and newts, although fish, small mammals and young birds may also be taken. Prey is grabbed, then swallowed alive. This species is a good swimmer, and is able to stay submerged for over half an hour (2). The grass snake is predated upon by badgers, foxes, domestic cats, hedgehogs and a number of birds. Relying on wariness for protection, the grass snake often 'plays dead' when threatened, which may dissuade certain predators from killing it. When caught, the grass snake hisses loudly, releases pungent and foul-smelling substances from the anal gland, and will frequently strike with the head, although it does not bite (2).