A Year in The Life of a Grass Snake

John Grundy News, Revealing Reptiles


Existing day to day in a marsh & living off frogs…

The elegant grass snake (Natrix natrix helvetica) is the least hardy of our UK widespread reptiles. Unlike the adder, which can be found abroad from February onward, the grass snake waits until late March – April to emerge from hibernation, when temperatures are averaging double figures. Some say 12 degrees Celsius is the trigger.

Grass snake head scales and colouring

They will bask in order to warm themselves up to activity temperatures before searching for a mate. The females release pheromones as they go in order to attract males. Once the males pick up the scent they follow, sometimes for days. Often several males will locate the same female and a struggle begins. Unlike the adder there is no elaborate ‘dance’ between males in order to win over the opposite sex. What ensues is a lot of nudging and shoving.

Using scent and temperature to locate nesting sites.

The males then go off to spend the summer ‘by the pool’, eating amphibians and fish and not much else. The females, after a month of basking and feeding, head off to nesting sites, in June, to lay their eggs. These can be muck heaps in farms or stables or compost heaps in gardens and allotments. Dry stone walls and beneath buildings where the temperature is constant. Naturally occurring piles of vegetation on river banks, that have been caused by winter floods can also be utilised. Any warm humid spot where they feel confident the eggs will incubate and hatch. Most females will return to their own place of birth and often several females will gather in communal nesting sites which have been used for many years.

Once the eggs are laid the females are free to leave, but it is not uncommon to find them enjoying the warmth and safety of the nest for several weeks. Even after the eggs have hatched and the young have dispersed the females will use the heap as a place to spend the summer. As with most warm humid spots amphibians and small mammals will venture in and these will supply the females with the food they need for the summer.

Several females ducking for cover in a compost heap.

It is often the case that the place in which they hibernate, the pond they feed in and the nest site where the eggs are laid are all quite a distance from one another. If an area of land is being managed for grass snakes then plenty of cover must be provided for them to safely move from one feature to the next. Newly-created ponds can be located next to hibernacula with nesting heaps maintained close by in order to reduce the risk of the snakes being predated whilst on their annual commute.

Ponds, woods and sunny glades are great places to look for grass snakes.

The grass snake will return to its hibernation spot by September and hopefully be well fed and in good condition in order to last the several months underground. They will remain dormant from October through to the next March or April.

Come out and join me on one of the Revealing Reptile Survey Training Sessions and learn how to identify, spot and survey for these remarkable reptiles.

John Grundy

John has spent more than thirty years honing his skills as a spotter of our region’s elusive and well-camouflaged reptiles. He can often be found wandering the moors of Durham looking for signs of life in the undergrowth. As the Revealing Reptiles Project Officer John frequently delivers reptile survey training to groups and individuals.

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