The Slowworm

The slowworm (also known as the blindworm) is a legless lizard that looks like a snake (Fig.1). It is neither slow nor blind. It is mainly nocturnal (active at night) or crepuscular (active at dusk/dawn) but sometimes basks in the sun during the day. They seem to be more active on warm damp nights ie. the same conditions that slugs favour. At certain times they can be seen with just about one or two inches (2.5cm – 5cm) of their head peering from their burrow waiting for prey to pass. They quickly withdraw at the slightest sign of movement from humans or large animals. Slowworms can be found hiding under rocks, logs, paving slabs and litter, especially black plastic, carpet or roofing felt. They seem to have a preference for old bits of discarded corrugated iron along with common lizards and many other small creatures. These places are known as refugia and many herpetologists (studiers of reptiles and amphibians) intentionally place these items in environments they are monitoring. If you live in an area where slowworms exist you can attract them by leaving an area of your garden wild and untidy. The slowworm hibernates during the cold months of winter sometimes gathering in groups of thirty or more under compost heaps, logs or tree roots. The place they do this is known as a hibernaculum. They tend to avoid areas that are liable to flooding. Care should be taken when digging over compost heaps that you do not accidentally kill any slowworms. May or October is reckoned to be the safest times to do this.

Fig. 1

Fig. 2

The slowworm's scientific name is Anguis Fragilis. Like other lizards, it can shed it's tail to escape predators - the tail eventually regrows into a short pointed stump (see Fig.2.) This is known as autotomy. The slowworm is one of several legless, burrowing lizards found throughout the world. The many snake-like lizards in the family Anguidae include the large European glass lizard and the California legless lizard. These animals have found legs a hindrance rather than a help, and the slowworm has developed the snake's technique of 'swimming' through soil and vegetation by writhing its highly polished, muscular body.(Fig.3)

Fig. 3

Fig. 4

Distribution
Slowworms are native to mainland Europe, southern Scandinavia, the British Isles and western Asia. They are not found further north than 60 degrees of longitude, but extend southwards. Although they are not native to Ireland, some were introduced around twenty years ago into the Burren area of County Clare where they seem to be thriving.

Habitat
Slowworms seem to prefer areas with loose, un-compacted, sandy soil. They can be found in meadows, allotments, gardens and rubbish dumps. They favour long grassy neglected areas with access to basking places. Railway embankments are particularly popular with slowworms, as are old overgrown churchyards. There could be many slowworms in your garden and you would be unaware of them unless you make a habit of looking under rocks and paving slabs. Another place they are found is resting beneath the leaves of daffodils during the stage that the leaves are dying back. They are hard enough to spot in a vivarium, as anybody who has kept them will confirm.

Anatomy
The slowworm is up from about 30-50 cm (12 to 20 inches) long. It has smooth, shiny bronze to grey skin, no legs, a small head, and eyelids that can blink (snakes do not have eyelids). Colour changes with age. Young slowworms are metallic gold-brown on top and brown or black on their sides, they have a dark stripe running down their back. Adult males are dull brown, gold or grey but lack the dark marking; some are marked with a few blue spots. The adult females keep the markings of the young slowworm (brown or black along the sides and with a stripe down the side). Females are usually larger than males. Its skeleton has vestigial limbs on, some shoulder bone and hip bone. They are also exothermic (do not create their own body temperature) and rely on basking or warm weather to get their metabolism going.

How to tell a slowworm from a snake
Scales: Snakes have rough overlapping scales whereas slowworms have smooth scales that do not overlap.
Eyes: Snakes have lidless eyes that cannot be closed. Slowworms have eyelids and are able to blink.
Tongue: Snakes have long, forked tongues. Slowworms have notched tongues.
Tail: When in danger, the slowworm can rupture special bones to shed its tail. Muscles and blood vessels also part to make a clean break. The new tail is made up of gristle. It is shorter and contains no special bones, so the shedding action cannot be repeated.

Diet:
Slugs, worms, spiders and snails, (which is why slowworms are often called the gardeners friend) also hairless caterpillars and other grubs.. They seem to be particularly fond of the small grey slugs that do most of the damage to plants. Gliding up on polished scales, it seizes its victim in its small mouth and slowly devours it. Unlike a snake it cannot stretch its mouth to engulf large prey, and anything larger than a small slug has to be chewed thoroughly before it is swallowed. (Fig. 4)

Reproduction
Slowworms reproduce from eggs which the female incubates within her body ie. they are ovoviviparous. The incubation period is about 90 to 100 days after which live birth takes place. They mate in April or May shortly after hibernation. There is brisk competition for mates among the males, who fight by seizing each other by the head or neck, entwining their bodies and writhing over the ground. The act of mating looks similar but is less violent and damaging.
Most young will be born in August but cooler temperatures can cause prolonged incubations and could delay the event until October or even later. If conditions are really poor the young remain inside their mother all winter and are born the next spring.
3 - 20 young make up a clutch and they are about 5cm ( 2 inches) long at birth.(Fig. 5) The pregnant female spends many hours in the sun in July and August, raising her body temperature to between 21 and 25°C to speed the development of her young each one in a separate egg sac. The new born are very active and able to feed themselves almost immediately on insects and tiny slugs but they take several years to grow to their full size. Sexual maturity is reached at 3 years for the males and 4-5 years for females..

Fig. 5

Fig 6

Longevity
The slowworm can live to a great age. A captive specimen in Copenhagen Museum lived for 54 years. Most wild specimens that live to full term reach around 30 years.

Predators
Young slowworms are eaten by frogs and toads. Adults may be preyed upon by snakes, hedgehogs, foxes, and birds. Their main enemy in the garden, like much of our native wild life is the domestic cat, which mauls them to death but rarely eats them. Some may die from eating slugs or snails poisoned by pellets laid down by the gardener. Humans kill slow-worms directly too, often by mistake when cutting long grass and also deliberately in believing they are adders. The slowworm is protected in the UK through the Wildlife and Countryside Act 1981. Many land developments are held up due to the site being inhabited by slowworms. Normally they are all captured and moved to a suitable site nearby.

Keeping slowworms in captivity
It is not illegal to keep slowworms in captivity under the afore-mentioned Act. This Act precludes people from trading in Slowworms or their parts either dead or alive, transporting for sale, intentionally killing or injuring. It does not prevent from 'taking' ie. keeping as pets or moving from one place to colonise another.(Fig. 6) They require a vivarium with a lot of places to hide and burrow. Sandy soil mixed with some peat moss is ideal. Also some small flat rocks to hide under or bask upon. Two or three small growing plants will complete the scene and the need to water these will remind you to keep the slowworms supplied with fresh water. Temperature should be kept at 60 - 70 degrees with a basking area of increased heat. Breeding is possible in captivity. A corner of a cool greenhouse or a shed with windows is a good place to locate the vivarium. This should be placed in a frost free but cool place during the hibernation season.