New findings from the latest Scottish Adder Survey have raised concerns about the future of Scotland’s only native snake.
The survey reveals that adder distribution in Scotland has shrunk significantly between 1994 and 2024. Reports show that the number of ten-kilometre grid squares where adders were spotted has fallen from 567 before 1994 to just 364 since then – a drop of 36%.
Despite this, the general range of adders across Scotland has stayed much the same as it was in 1994. They remain absent from areas such as the Central Valley, the Outer Hebrides, the Northern Isles and much of the uplands between Glasgow and Inverness.
The study – a collaboration between NatureScot, Amphibian and Reptile Conservation, and the Amphibian and Reptile Groups of the UK – also uncovered clear gaps where adders have disappeared, and growing concerns that the species is becoming less common.
Marking 30 years since the original Scottish Adder Survey, researchers followed similar methods this time around: collecting information through questionnaires, revisiting earlier survey sites, and analysing historic adder sightings from several sources.
The latest assessment from the Great Britain IUCN Red List classifies the adder as Near Threatened across Scotland, Wales and Britain as a whole, and as Vulnerable in England. Habitat loss, disturbance, fragmentation and lack of conservation efforts are all thought to be contributing to the decline.
“Reptiles are a challenging species to study in Scotland, due to their low detectability combined with how vast and remote Scotland can be,” says Catherine Whatley, Amphibians and Reptiles Advisor at NatureScot, “so we haven’t been able to draw robust conclusions about changes in the adder population size.
“The evidence we have gathered points to a picture of decline, with the contraction in adder distribution quite alarming.”
Adders are shy and secretive creatures, more likely to avoid people than seek them out. Though they are venomous, bites are rare and reactions are usually mild.
In Scotland, adders can be found in grasslands, woodlands, upland moors and coastal areas – and sometimes even in man-made environments such as railway embankments, roadsides and golf courses.
They are protected under the Wildlife and Countryside Act 1981, meaning it’s illegal to harm or kill them. Adders are also listed on the Scottish Biodiversity List as a species of key importance for conservation.
“The adder, along with all Scotland’s reptiles, is an important species that contributes to Scotland’s biodiversity, so it’s vital that we have a picture of how they are faring,” says Whatley.
“Further research is needed to give a clearer picture of their status, so that we can carry out the most effective conservation work.”
Main image: adder. Credit: ARC Trust/Chris Dresh
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