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Grass snakes in your garden

Grass snake © Richard Bowler

One day you may lift the lid off your compost bin and come face-to-face with a grass snake. This handsome, harmless animal seeks out warm spots in which to lay her eggs. The heat generated by rotting vegetation provides perfect incubating conditions for the eggs, which can number up to 40.

Another favourite nesting spot is under rotting logs. Depending on the temperature in the nest, the young grass snakes should hatch about two months later and adults can live up to 15 years.

Juvenile grass snake © Margaret HollandFrom August, the hatchlings - each a mere 10cm long - emerge from their shells and have to fend for themselves. The young snakes, sometimes called 'shoelaces, face many dangers and make easy pickings for predators.

The grass snake is the largest of our three UK native snakes (two of which occur in Wiltshire). In the summer adults spend their time basking in the sun and foraging for food. They hibernate between October and March, seeking out frost-free places.

Grass snakes in compost bin © Paul Darby WSBRCCompost heaps come in useful again as cosy winter nests.

They are excellent swimmers, and ponds, slow moving streams, marshy ground or ditches provide them with their preferred diet of frogs, toads or newts - which they swallow whole. They may also feed on fish, small mammals and young birds if they can catch them.

Grass snakes typically grow to one metre in length but sometimes much longer. They lack any venom and so, despite their size, they are vulnerable to being preyed upon by badgers, foxes, buzzards and other raptors, and even the domestic cat. To protect themselves from predators they will initially hiss and coil, but if the attacker persists, grass snakes will roll over, open their mouth wide, go limp and feign death. A different strategy is to exude a foul-smelling liquid from their anal gland and repeatedly strike at their attacker.

Loss of habitat lies behind their dwindling numbers and they are now a protected species.

How to identify grass snakes

Grass snakes are usually grey-green to dark olive in colouring although colours can vary. They have a distinctive yellow band around the neck and black bars running down their sides and sometimes on the back. On their underside they have a checkering of black and white scales. They have rounded heads with black lines running from beneath their eyes to their mouths. Their forked tongues are bluish.

We have recent records of grass snakes at several of our nature reserves such as the Lower Moor Farm complex, Blakehill Farm and Ravensroost Meadows. Click here to learn more about reporting sightings of grass snakes and other wildlife.

This article was written by our volunteer Wildlife Information Officer, Ernie Bohm.

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