Study raises concerns for adders in Scotland - NatureScot

Evidence from a new report raises concerns about the status of adders in Scotland.

The latest Scottish Adder Survey found that the reported distribution of Britain’s only venomous snake shrank significantly in Scotland between 1994 and 2024.

It found that the number of ten-kilometre squares in which adders have been reported in Scotland has substantially declined, from 567 pre-1994 to 364 from 1994 onwards – a 36% decrease.

The overall range of adders is largely the same as 1994, with the native snakes remaining absent from the Central Valley, Outer Hebrides and Northern Isles, as well as a large proportion of the upland region between Glasgow and Inverness.

The study, a partnership between NatureScot, Amphibian and Reptile Conservation, and Amphibian and Reptile Groups of the UK, also reported distinct gaps in adder distribution across Scotland, and perceptions that the adder is now becoming less common.

Thirty years on from the first Scottish Adder Survey, the research repeated the work carried out in 1994 using similar methods: a questionnaire and a re-survey of the original ten-kilometre square study sites, combined with historic adder records from several different sources.

The Great Britain IUCN Red List assessment considers adders to be Near Threatened in Scotland, Wales, and Britain as a whole, and Vulnerable in England. Their declines have been attributed to several pressures, including habitat loss and fragmentation, disturbance, and a lack of conservation management.