Slow-worm compost survey |
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The slow-worm is an extraordinarily secretive animal. Although allotment holders may be familiar with the slow-worm, ecologists know surprisingly little about its ecology. Slow-worms spend most of their lives underground or deep under vegetation. We are most likely to find them in compost heaps, or when they are warming up under bits of old wood, carpet, rubber, polythene sheeting or corrugated iron. However, the few animals we see are usually just the tip of the iceberg as most slow-worms are rarely observed. In suitable locations slow-worms can occur in considerable numbers, with over 1,000 per hectare recorded in parts of Southern England. The slow-worm is the original gardener’s friend; they eat slugs and other invertebrates, and are completely harmless to humans. |
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As with many other species in Britain, the slow-worm has suffered dramatic declines in recent decades, mainly due to habitat loss and intensive land-use. So the populations remaining in allotments and gardens could be of particular importance to the survival of this species, especially in urban areas, in much the same way as common frogs do very well in garden ponds. We think that unkempt areas of garden are the most important factor, but compost heaps could provide a key focus for slow-worm activity in the garden or allotment. In order to help us understand more about slow-worms and their use of compost heaps, we are undertaking a national Slow-worm Compost Survey. You can take part in the online survey here.
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| Creature features | ||
Despite its snake-like appearance, the slow-worm is in fact a legless lizard. Its body is cylindrical and its colour is usually a shiny, metallic grey or brown. Closer inspection reveals differences in coloration and shape between sexes, individuals and animals of different ages. |
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Female slow-worms tend to have dark flanks and a thin, dark stripe down the back. They also have relatively smaller heads than males. Males tend to be a uniform grey colour, lacking the longitudinal stripe and often have a scattering of blue spots. Older slow-worms tend to have a duller appearance and are often battle scarred. Slow-worms give birth to ‘live’ young. Newly hatched slow-worms are like miniature versions of adult females, with dark sides and stripe along the back, contrasting with a striking yellow, gold or copper background. |
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Adult slow-worms can grow up to 45 cm in total length, whereas the newly-born young are 7 to 10 cm long. In common with other species of lizard, the slow-worm is distinguishable from snakes by the visible eyelids (you may see them blink), and the ability to shed its tail. |
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Shedding the tail (autotomy) is a defence response to help escape from predators by providing a distraction. All the bones in the tail (vertebrae) have a plane of weakness in them. When caught by a predator, the slow-worm is able to contract muscles in its tail that break one of the vertebrae in half, and detach the tail. The shed tail continues to wriggle and squirm for quite some time and, hopefully, distracts the predator long enough for the animal to escape. The tail does eventually re-grow, but the replacement is never as good as the original and it is easy to spot a re-grown tail. |
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Private life of the slow-worm |
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Slow-worms hibernate throughout the winter months, sometimes sharing hibernation sites with other animals. In spring, males often fight, presumably to see off potential rivals for mates. Even mating itself can be quite aggressive, with amorous males holding females tightly in their jaws. Scarring is common, particularly around the neck. Despite these conflicts slow-worms are harmless to humans, and do not bite. |
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A brood of young is produced in September to October. Each baby is born in a transparent membrane, from which it emerges almost immediately. Slow-worms are long-lived: 20 years or more in the wild, and over 50 years recorded in captivity. In urban areas, many older animals lose their tails, often due to cats. Careless mowing can kill them, and it is always best to disturb any long grass before mowing. Likewise, as slow-worms tend to bask underneath things, it’s wise to check beneath any plastic sheeting or other objects before you place heavy things on top of them. |
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| Distibution and habitat preferences | ||
The slow-worm occurs throughout most of Europe, including virtually all of Great Britain, although it tends to be most abundant in the southern counties. Slow-worms are the reptile most commonly reported from urban areas, where they often occur in gardens, parks, allotments and derelict or brownfield land. They need long grass and overgrown areas of bramble etc; therefore they tend to favour unkempt areas of gardens and allotments. Of our native reptiles, the slow-worm seems to be the happiest to live in close proximity to humans, provided its habitat is not disturbed too dramatically. |
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Although it is difficult for ecologists to study the slow-worm, there are fears that the species may be in a worrying decline, primarily due to the loss of its semi-natural habitats such as rough grassland, woodland/field edges, hedgerows, heathland and scrub and through intensive agricultural practices. When an area of habitat is destroyed, its slow-worm population is almost certainly doomed. They cannot travel far, and unless good habitat remains very close by, the population will be lost. Like all our reptiles, the slow-worm is protected from killing and injury, under the Wildlife and Countryside Act 1981. |
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| How can you help conserve slow-worms | |||
Slow-worms are a welcome component of the compost ecosystem. As the king of the food-chain, they feed on pests such as garden slugs and snails, and possibly also the New Zealand flatworm. By joining in with our Slow-worm Compost Survey, you can help us to understand more about slow-worm ecology and just how important composting is to this secretive animal. |
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There are a number of organisations helping to conserve slow-worms and other species of reptile and amphibian. Why not join your county Amphibian and Reptile Group which may be organising conservation tasks in your area. A number of groups have published their own books recording the species present in their county, such as Amphibians and Reptiles of Surrey (Julia Wycherley and Richard Anstis, Surrey Wildlife Trust, 2001) and Frogs and Friends: The Distribution and Conservation of Amphibians and Reptiles in Nottinghamshire (Sheila Wright et al, Nottingham Natural History Museum, 2004). Publications like these not only provide useful guides on slow-worms and other species, but the profits from book sales also help to support local conservation projects. |
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| Based on original text by Gareth Matthes and the HCT for the Community Compost Network (Growing Heap, No.37, Spring 2006) | ||
