Slow Worm

The Slow Worm has a widespread distribution across Europe but within Britain it is most commonly reported from the southern counties. With no visible legs, this lizard is often mistaken for a snake, something that may engender a feeling of panic in the gardener who encounters one for the first time. This is unfortunate, in some instances especially so for the Slow Worm, not least because Slow Worms do a tremendous amount of good in controlling garden pests like slugs.

Behaviour and Ecology

Slow Worms are not usually seen abroad during daylight but are most commonly encounter sheltering under logs, stones or other objects. They emerge from these at dusk to search for slugs, worms, spiders and various insects.

The Slow Worm is ovo-viviparous, which means that the eggs hatch either as they are laid or some minutes later. The emerging young from an average litter of 6-12 become independent straight away and are miniature versions of their parents just 6.5-9 cm in length. By two years of age they can reach 21-23 cm in length. With at least one captive individual living beyond 50 years of age, wild individuals could possibly live for 20 years of more.

Identification

An adult Slow Worm is typically about 30cm in length, with a uniform cylindrical body – i.e. without the narrowing behind the head that gives snakes their characteristic ‘neck’. Unlike a snake, the Slow Worm has visible eyelids that blink regularly and smooth, shiny scales that display a metallic appearance. It is the extreme smoothness of the scales that results in the ‘highly polished’ appearance. The overall body colour is a shiny grey-brown, usually with thin longitudinal stripes of a darker colour. The exact appearance may vary from one individual to another but older males usually sport a series of small spots, blue in colour.

The use of gardens - results from Garden BirdWatch

Hibernation lasts from late October through to the start of March, with Slow Worms sometimes sharing their hibernacula with other reptiles. Mating, often quite a rough affair, takes place some weeks after emerging from hibernation.

Seasonality in the use made of gardens by Slow Worms during 2003

Slow Worms show a readiness to live within urban habitats to a greater extent than any of our other reptile species, often colonising newly created brownfield sites, yet they are probably the least familiar of our reptiles.

Differences in the use of rural, suburban and urban gardens during 2003

Although commonest in southern regions, Slow Worms are found across Britain but are absent from Ireland. Click here to see a map showing the distribution of Slow Worms within gardens at the national level, as recorded by BTO/CJ Garden BirdWatchers during 2003.

Regional variation in the use of gardens by Slow Worms

Click here to see what the region codes on the above graph mean.

Garden BirdWatch | BTO Home | CJ WildBird Foods Home
Garden BirdWatch online is organised jointly by the BTO and CJ WildBird Foods
Email: gbw@bto.org
Page last updated 19 April, 2004

Terms and Conditions | Privacy Statement          © British Trust for Ornithology
BTO, The Nunnery, Thetford, Norfolk IP24 2PU, UK. Registered Charity Number 216652.
CJ WildBird Foods Ltd. The Rea, Upton Magna, Shrewsbury SY4 4UR, UK