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WILDLIFE OF NORTHERN ENGLAND

A look at snakes- featuring the grass snake

Not many animals are so much dreaded than the snake, even though we only have one venomous kind in the UK-the adder. All snakes have long cylindrical bodies with a well marked flattened head, but generally with no distinct division between the body and tail. They posses no limbs and it is only a few species, as for an example the Pythons that studies have revealed, via dissection, have two small bones which are recognized as the rudiments of the hind limbs.

The so called scales consist of a wrinkled scaly skin and a delicate epidermis, covering the whole body even to the eyes and which is shed completely several times in a year. A flattened head is interesting  with its widely cleft mouth, movable upper jaw, and, loosely connected lower jaw. This arrangement  allows the creature to swallow large mouthfuls.

The teeth are curved backwards and is only used for seizing prey, and are solid in harmless snakes, but have an outer groove in other species, or are perforated by a duct in the venomous kinds, to convey the venom from the poison gland, 

 

 

Boa constrictor-courtesy of Ted Baker Creative commons share alike-2.0 License

 

Boa constrictor (2).jpg

Forked tongue.

The forked tongue lies in a kind of sheath, and is highly movable organ of touch, which to some extent replaces the deficiencies in other senses. However, these creatures do not require limbs for rapid movement either on land or in water. This is achieved by very quick contractions of the vertebral column,, and by supporting them by the free end of the ribs.  Only a few a few species climb. 

All snakes feed in living creatures which are dispatched   either by crushing them or by biting them. Once they have satisfied their hunger they sleep in a torpor like manner. Snakes are encountered all over the tropical and temperate parts of the world, but they are far more numerous in hot countries than in cold ones.

A Look at Non-venomous snakes

In these snakes all the teeth are equally developed. There are two parallel rows on each side of the upper jaw, and a close series of curved teeth in each division of the lower of the lower jaw. In the Boa constrictors, the head is triangular and flattened and the jaws open very wide and are armed with strong teeth. The head is covered with plates and the throat with scales. There is a horny claw on each side of the base of the tail, containing rudiments of the hind extremities. Boas inhabit Asia, South America and Africa. The Boa constrictor inhabits tropical America and attains the length of 20-30 feet.

 

Grass snake.

File:The Grass Snake - Natrix natrix.jpg

Public Domain courtesy of Darius Bauzys   Wikicommons.

The Grass snake Natrix natrix

Now we review one of Britain's non-venomous snakes the Grass snake Natrix natrix, formerly Tropidonotus natrix, not to be confused with the American species Opheodrys vernalis or Opheodrys aestivus, that are also referred to as grass snakes in north America.

The grass snake was more commonly referred to as the ring snake it days gone by  { and to a certain degree still is today} and according to the book ' The Life History of British Serpents' {1901} " The ring snake is by far the most numerous of the British serpents, but while this is so, it is by no means follows that its distribution is uniform throughout the country, and indeed this is far more than actually is the case."-----" In the north of England it is scarce, the Cumbrian mountains apparently offering an obstacle to its progress on the north west. The ring snake is seen in greatest abundance in Wiltshire, Gloucestershire,  and in some of the Welsh counties, but it has universal distribution throughout the south of England except in some restricted districts where local conditions are altogether in favour of the Adder."

 

Description of the grass snake.

The most striking feature an observer of the grass snake will see is the yellow/orange collar, divided in the middle by a black line on the back of the neck. Immediately behind the collar is an incomplete part being a dark brown or black patch, the incomplete part being on the ventral surface. Also the dark band is much wider on the sides of the neck than on the back of the snake.

Behind this again, the general body colour is olive green darker above than below, shading off to light greenish yellow on the creatures sides { the body colouring can be variable and greyish green, grey blue or bluish black may occur}. Along the sides of the snake there are two irregular shaped black patches one row on either side of the body,. Above these, on the back are two parallel rows of smaller black spots. The underside is of a whitish colour.

The young, when first born, are darker all over, but they soon show all the colouring of the adult, the collar becoming bright within a few weeks. The grass snake may grow to a far greater length than the adder or the smooth snake, but it varies depending on locality The average length of an adult is 30-36 inches however, there are much larger ones on record. F.S. Aflao mentions that Lord Londesborough had one measuring  five feet eight inches from the New Forest, although such specimens are regarded as being exceptional.

In proportion to its length, the ring snake is much thinner and more attenuated than the adder, especially towards the tail. The tail is regarded as another identifying feature distinguishing the grass snake from the adder. The tail of the grass snake tapers to a very fine point, while the tail of the adder is somewhat blunted. Although this is generally the rule, it is not always the case. Specimens of grass snakes have been recorded with tails almost as blunt as that of the adder, however, it is likely that such specimens have been deprived of that part of the tail through some accident or part predation.

Its deterrent against predators is provided by two glands near the anal orifice which emits a powerful and unpleasant odour when it is disturbed.

 

The grass snake feigning death- note the whitish under parts.

Courtesy of Piet Spaans/Viridiflavus Creative commons Attribution share alike 3.0 Unported license.

Habitat of the grass snake.

They always occur not far from water. Damp marshy districts seem to meet their requirements. Hot ,dry arid places they avoid, which conversely is the habitat of the adder. Perhaps the most favourite haunt of the grass snake { if available} is a quarry or other pit in the neighbourhood of a water body such as a pond or river, where they take the luxury of a swim in the sunshine and may spend the winter hibernating in such a location.

the lush long grass of marshy land often keeps them supplied with a good source of food for in such localities the lizards and amphibians congregate. They may also be encountered on grassy banks in undulating fields, but always more common in well watered districts. The grass snake will hunt prey at the eges of water using sight and their sense of smell to locate them.

In the main their diet consists of amphibians, frogs and toads.  the process of swallowing a frog is a task that requires some time and careful manipulation. The frog is as a rule seized by the hind leg simply because it is trying to escape it pursuer . Once caught the frog makes no further attempt to struggle. Once the hind leg is swallowed the body of the frog begins to disappear the wide opening jaws allowing the passage large articles of food.

Being an expert swimmer  the snake spends part of its time to a lesser or greater degree, depending on the individual in the water, so it is not surprising it finds a considerable portion of its food in that element. other articles of prey includes mice, birds and their eggs, especially newly hatched ground nesting species.

Grass snake in water-note the saliant collar colouring

Image courtesy of Tony Wharton  of Froglife. 

Breeding and young.

the grass snake is a oviparus animal, that is to say an egg-laying animal. The female lays her eggs, the number varying between animals but usually in groups of between 8-40. Studies have revealed that their size and number varies according to the amount of moisture absorbed and to the time of development, but they are generally about an inch long {two and a half centimeters} about the size of a pigeon egg.

The eggs are laid in late Spring or early summer. Once they have been deposited in a favoured location they are abandoned by their mother who takes no part in rearing her young.The separate eggs stick to each other by means of a glutinous secretion which is deposited with them. The covering of the embryo is not a shell but a tough leathery membrane through which moisture can penetrate. the period of development varies somewhat with the amount of heat and moisture to which the eggs are exposed, but is generally about eight weeks. this is not the total length of development however, as the young have reached a certain stage before the eggs are deposited by the female. The young are just over six inches long {12cm} when they hatch and are immediately independent.

Conservation issues

Grass snakes are found throughout England and Wales and they are Britain's only egg laying snake. They are protected under the Wildlife and Countryside Act 1981 -It is illegal to deliberatety kill, injure or sell grass snakes

Reuse of images.

The images on this page may be reused. However, the name of the relevant author must be attributed along with any accompanying license.

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