Newsletter 43 - Spring 2005

The Smooth Snake (Coronella austriaca) & the New Forest Survey.

Adrian Barnes

This is a widespread and, in places, abundant snake. Its range stretches from southern England through France and the Low Countries to North Spain and Portugal, Germany, Denmark, Norway and Sweden (as far north as 63° Lat), Switzerland, Austria, Italy and Sicily (though not Corsica or Sardinia), the West Balkans and Greece, and European Russia as far north as 57° Lat. In Asia, it extends through Turkey to Azerbaijhan, Georgia, Armenia and northern Iran.

In the two areas in southern England where Smooth Snakes are found (West Surrey/East Hampshire and Dorset/West Hampshire), widespread destruction of the habitat has greatly reduced the area of distribution in recent years. The British Herpetological Society, through its Conservation Committee1, is implementing measures to save these popula­tions from extinction; see below.

The favourite habitat of the Smooth Snake over most of its range is light or sandy soils with thick heather or similar vegetation. It seems to make little difference whether such areas are moderately wooded or open. It is often found near water, but not invariably so. At least in the northern part of its range, it favours south-facing slopes and appears to prefer undulating or hilly country; towards the eastern edge of the range, it is more likely to be found in steppe ravines than on open plains.

Adults reach a length of about 18 to 20in, though larger specimens of up to about 29in have been recorded. The body is moderately slender and the head comparatively small, with a rounded and slightly depressed snout.

The dorsal colour is brown, grey or reddish with a series of small black or dark brown spots along the centre section of the back and tail. These spots are generally in the form of a double row but often, and on the neck usually, spread out to form narrow crossbands. Along the flank there is often a series of more obscure spots. The top of the head is dark, particularly so at the rear and in most specimens a more or less distinct curved line, with the outside curve forward, runs from eye to eye over the forward part of the head. (it looks like a crown; hence the Latin name of the snake) A dark line, intact or nearly so, runs from the side of the snout through the eye to the angle of the mouth and along the side of the neck. There are often, though not always, two short, parallel lines along the top of the neck just behind the head. The undersides are whitish, grey, brown or reddish, with or without dark spots; there is a tendency towards brown or reddish in males, and grey in females. Newly born young are generally darker than the adults, being normally dark grey with distinct black markings, particularly on top of the head, and their undersides are reddish.

The Smooth Snake burrows well in loose soils and spends a lot of its time under cover. It does, however, emerge from time to time to bask in the sun, particularly in the morning and after rain, occasionally climbing up into heather or low vegetation for the purpose. It avoids very hot sun. Its move­ments, when undisturbed, are slow and deliberate, and when alarmed it may make a short, sharp (though not particularly fast) dash for cover, but is more likely to creep slowly into hiding or even 'freeze'. If caught, it sometimes discharges a pungent fluid from its anal glands. It may also bite if handled, but without striking. In most parts of its range, the Smooth Snake hibernates from about the middle of October to the end of March or early April.

The favourite food is lizards. As the head and gape of the Smooth Snake are small, the largest lizard it can swallow is about the size of an adult Common (Viviparous) Lizard, Lacerta vivipara, Even a very large Smooth Snake would have difficulty in swallowing a full-grown Sand Lizard, L. agilis. Smooth Snakes have been known to attack quite large lizards, sometimes seizing them by the tail, which if discarded by the lizard, is swallowed by the snake. Small snakes, including the young of vipers, are also readily eaten, as well as young rodents. There is evidence to suggest that Smooth Snakes use their sense of smell to find young rodents in underground nests. A Smooth Snake caught in West Hampshire disgorged three full-grown Pygmy Shrews. Young Smooth Snakes eat very small lizards as well as flies, spiders and other invertebrates.

There is some evidence that Smooth Snakes frequently hibernate in pairs or larger numbers, and mate at about the time of emergence from hibernation. On a number of occasions, however, mating has also been observed in late summer. Males have been seen to fight each other at such times, using both teeth and coils. The young are born alive (usually in a transparent membrane from which they quickly free themselves) in August or early September, and recorded litter sizes range from three to fifteen. The lengths of newly born young vary between about 4in to 7in. They grow very fast and in cap­tivity have been known to increase from 8 to 15in in nine months. Two subspecies are currently recognized. The one found in England is Coronella austriaca austriaca.

The Herpetological Conservation Trust (Dr. Chris Gleed-Owen) is currently co-ordinating a survey of Smooth Snakes in the New Forest in order to establish location of colonies, numbers and habitat preferences in order to be better placed to liaise with stakeholders in the management of the New Forest.

In 2002 circa 400 small sheets of corrugated iron were placed at likely locations across the whole of the New Forest. These sheets are known as ‘Refugia’ because snakes and lizards are attracted to them for shelter and as a relatively secure place to warm up.

For the past two years volunteers have regularly visited these refugia (or ‘tins’ as they are more commonly called) to check if a snake is in residence. Some parts of the forest have fairly high density populations (or the tins are in the right place!) whereas others appear more thinly populated. This appears to be the case in the Forest north of the A31, although snakes have been observed in all key areas from Black Gutter Bottom to Picket Post.

Please note that it is an offence to disturb these snakes in any way unless you have a licence to do so (Wildlife& Countryside Act 1981).

The Trust has just been advised that it must remove all of the tins from the forest because of concerns regarding the potential for them to damage ponies’ legs. As a result the Trust is desperately trying to find the money to purchase corrugated bitumen sheets in order to be able to continue this valuable work. In addition there is a continual shortage of volunteers. Anyone interested in volunteering to help with the survey or providing funds for ‘refugia’ should contact Dr. Gleed-Owen on 01202 391319 or at chris.go@herpcontrust.org.uk

This article was based on the talk given by Adrian Barnes to the New Forest Section on 12 May 2004.

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