A glimpse of a grass snake slipping through a pond or basking in the sunshine is one of the most exciting wildlife encounters summer has to offer. Britain's longest native snake can grow to more than 1.5 metres in length, yet despite its impressive size, it is completely harmless to people.

Grass snakes are found across Hampshire and the Isle of Wight and are particularly associated with wetlands, ponds, ditches and marshes. However, they also thrive in rough grassland, woodland edges and even gardens, especially where ponds provide plenty of food. Warm summer days offer the best chance of seeing them as they emerge to bask in the sun, raising their body temperature before becoming active.

Usually greenish-grey in colour, grass snakes are easy to recognise thanks to the distinctive yellow and black collar behind the head. Females tend to be much larger than males and can reach lengths that surprise many people encountering one for the first time.

Unlike many reptiles, grass snakes are excellent swimmers. They can often be seen moving gracefully through water with only their heads visible above the surface. Their favourite prey includes frogs, toads and newts, although they will also eat fish, small mammals and even young birds. A healthy pond can provide everything a grass snake needs to thrive.

Summer is a particularly important time in their life cycle. Females lay between 10 and 40 eggs in warm piles of rotting vegetation, compost heaps or manure heaps. The heat produced as the material decomposes acts as a natural incubator, keeping the eggs warm until they hatch in early autumn. This unusual strategy makes compost heaps surprisingly valuable habitats for wildlife.

Grass snakes have a remarkable defence mechanism. If threatened, they may hiss loudly, flatten their bodies or release a foul-smelling liquid to deter predators. If all else fails, they sometimes perform an extraordinary act by playing dead, rolling onto their backs and hanging their tongues out in an attempt to convince predators they are no longer worth eating.

Although widespread, grass snakes rely on connected habitats and healthy wetlands, both of which have declined in many areas. As a result, the species is protected under UK law and recognised as a priority species for conservation.