Grass Snake – Natrix helvetica

The grass snake is the largest reptile in Britain, growing to about one metre long. Its preferred habitat is damp areas like ponds, reservoirs and marshes, also making use of the surrounding terrestrial habitat such as grassland, scrub and woodland. They feed mostly on amphibians and small fish. If threatened, they may lie still, pretending to be dead, but can rear up in mock attack, hissing. They also excrete a foul-smelling substance, particularly if handled, but are otherwise completely harmless to humans.

The females mate, at most, every other year but can live to 25 years of age. They are the only British snakes to lay eggs. In June-July the females lay eggs in dung heaps and rotting vegetation including garden composts, which provide the required heat to successfully incubate them. The eggs hatch 6-10 weeks later. The hatchlings, which are just 6cm-10cm long, are entirely independent.

In warm weather they can be seen basking in the sun. Like all snakes, they are cold-blooded and can only be active and hunt when they raise their body temperature in this way.