A major new study has found that the distribution of adders in Scotland has shrunk dramatically over the last three decades.
The Scottish Adder Survey has revealed a 36% drop in the number of areas where these snakes have been recorded since 1994.
Only 364 ten-kilometre squares now report adder sightings compared to 567 prior to 1994.
The survey paints a stark picture for the country’s only native snake, suggesting it is slowly vanishing from parts of its former range.
Despite the drop in numbers, the overall spread of adders remains much the same, with large regions still showing no sign of the species.
Adders are still missing from the Central Valley, the Outer Hebrides, the Northern Isles, and upland areas between Glasgow and Inverness.
This latest study repeated the methods of a 1994 survey using questionnaires, field visits, and records from various sources.
The work was carried out by NatureScot, Amphibian and Reptile Conservation, and Amphibian and Reptile Groups of the UK.
The findings reflect growing concern about the future of the adder in Scotland.
On the IUCN Red List, adders are now classed as Near Threatened in Scotland, Wales and across Great Britain.
In England, their situation is even more fragile, with adders now listed as Vulnerable.
The decline has been blamed on several threats, including habitat loss, disturbance, and poor conservation management.
Catherine Whatley from NatureScot highlighted the difficulty of monitoring reptiles in Scotland’s vast landscapes.
She said the signs of decline are worrying, especially given the adder’s low visibility and elusive nature.
She praised the public response to the survey and said more research is urgently needed.
Adders play an important role in the ecosystem and are part of Scotland’s rich natural heritage.
Despite being venomous, adder bites are usually mild and they are known for their shy, secretive behaviour.
They favour quiet spots like woodland edges, heathland, and coastal scrub, but are occasionally found near human activity.
Adders can turn up along railway lines, road verges and even golf courses.
In Scotland, they are protected under the Wildlife and Countryside Act 1981 and cannot be harmed or killed.
They are also on the Scottish Biodiversity List, which highlights species needing focused conservation.
Conservationists now hope this new data will lead to better protection and more targeted habitat work.
Without urgent action, the adder may vanish from many parts of Scotland where it once thrived.
