Adder Surveys 2022

Published by Jem Gibson on

The adder is the fastest declining reptile species in Britain. Prior to 2008, records of sightings of adders (Vipera berus) and data on their distribution within the Quantock Hills AONB had been sparse, with only 24 records submitted to the Somerset Environmental Record Centre from 2000-2011. From 2011-2015 the Reptile and Amphibian Group for Somerset (RAGS) undertook a survey of adders within the Quantock Hills AONB, and identified 12 spring assemblages. An assemblage is an area where 3 different individual adders have been sighted. The spring assemblage areas are often an indicator of a nearby hibernaculum, (the place where the adders will hibernate)as in spring the adders emerge from their hibernaculum and bask in the sun nearby.

Adder camouflaged in bracken
Adder in Bracken: Scott Passmore, 2022.

In Spring 2022, volunteers from the Quantock Landscape Partnership Scheme and the Reptile and Amphibian Group for Somerset (RAGS) undertook a survey of adders within the Quantock Hills AONB.

26 surveyors and 2 community groups with 19 participants were given training in survey techniques for adders.

The primary aim of the survey was to determine the presence of adders across areas of the Quantock Hills AONB at sites suspected to support adder populations.

A secondary aim was to engage new volunteers with adder surveying and therefore wildlife surveying more generally. We hoped to increase awareness of adders, the habitats they live in, the increasing threats to populations and encourage people to think about what more could be done to protect them.

The Quantock Landscape Partnership Scheme hosted an introductory session on the 19th of March led by John Dickson from RAGS. 25 participants were trained on the lifestyle of adders, how to identify adders from other snakes and how to sex them. They also learnt about the conservation status, legal protection, habitat and distribution of adders on the Quantocks and wider Somerset. Finally they were instructed on health and safety procedures surrounding the adders themselves, the survey methodology and the wider survey environment, including tick safety and the lone working policy.

A total of 7 sites of varying sizes, all totalling 5.09 square kilometres, were surveyed. Surveys commenced in late March, when adders emerge from hibernation and terminated in mid – May. During this time the newly emerged adders do not travel very far from their hibernacula, their time being spent basking, sloughing old skins and mating. By late May mating is complete and they then disperse from their hibernation areas to their summer feeding grounds, becoming less concentrated and more elusive. Where multiple sightings of adders are made prior to this dispersal it is probable that they are occupying a hibernation area.

Surveyors were trained on how to identify adders and how to search for basking adders, and instructed to survey during a period of suitable weather conditions,. Once an adder is found participants record its position using the GPS, identify its sex and life stage and record details of the vegetation structure around the basking site. Where possible a photograph is taken of the individual.

Map 1: The seven survey areas across the Quantock Hills AONB.


A total of 10 adders were sighted during the survey period, with 4 females and 6 males, all in adult life stage. The ten sightings were across 4 of the survey areas. Area 3 yielded the most sightings. *Area 5 yielded no adder sightings however a sloughed skin was discovered.

Area NumberArea NameAdder SightingsSex
1Longstone Hill1M
2Great Hill0 
3Triscombe/Aisholt42M 2F
4Vinny Combe0 
5Lydeard Hill/Triscombe0* 
6Wilmot’s Pool22F
7Beacon Hill33M
Table 1: Survey results and sightings.

For data protection reasons, the exact location of the adder sightings cannot be shared. Adders are particularly vulnerable to disturbance; if they have to spend too much time hiding they cannot stay in the sun and gain enough energy to mate.

Five of the ten sightings were recorded on the south or south-westerly facing slopes. The sightings were all in areas where the heath had a mix off immature scrub, trees and grass. It is believed that due to the heathland landscape, most adders on the Quantocks are probably using transient holes such as the burrows of small mammals or gaps under the roots of plants, and while they may return to the same vicinity to hibernate each year they will not necessarily use the same hole each year and neither will they necessarily ‘den up’ together in large numbers. This means that it is difficult to pinpoint exact hibernacula.

The recorded sightings allow a picture of presence of adders but is in no way a comprehensive illustration of population size or density.

QLPS in association with RAGS plan to continue surveying the Quantock Adder populations. The known assemblage areas will be monitored to ensure the adder populations are surviving. Beyond the heathland, on the ‘shoulders’ of the hills the habitat changes, yet there is a considerable volume of anecdotal evidence that adders are also found in some areas on these lower slopes where the habitat consists of the corners of rough grazing land, bracken covered slopes and the edges of wooded combes. While not recognised as such typical adder habitat as the heathland on the plateau, it is entirely possible that areas of equal importance for adders could exist at these lower altitudes. Next year we will explore more of these areas to see if we can locate more adder assemblage areas.

If you wish to get involved with adder surveying in Spring 2023, please get in touch by emailing Jem Gibson, QLPS Wildlife Officer: