Almost one third of Great Britain’s amphibian and reptile species are threatened with risk of extinction, according to a new report by ARC. Moreover, two species often considered common may be heading down a similar route.

With support from Natural England, ARC has undertaken the first regional assessment of extinction risk using the IUCN Red List method, a globally recognised approach. Whilst typically applied across the global range of a species, Red Listing can be applied at smaller scales, and ARC did this for all native amphibians and reptiles at Great Britain and country levels.

Sand lizards are assessed as ‘Endangered’ in Great Britain, contrasting with their global ‘Least Concern’ rating

The exercise reveals that 4 out of 13 species (31%) are in one of the “Threatened” categories, meaning they face a tangible risk of extinction at country level. The most threatened species is the northern pool frog, now classed as “Critically Endangered”. The natterjack toad, sand lizard and smooth snake are each assessed as either “Endangered” or “Vulnerable”. The common toad is “Near Threatened” in Great Britain, England and Scotland, and the adder is “Vulnerable” in England and “Near Threatened” at all other scales.

All of the species are deemed “Least Concern” at a European or global level, the lowest threat category, meaning that is there is no appreciable risk of extinction. These new results therefore usefully highlight how extinction risk varies substantially according to the spatial scale of assessment. The main factors driving threat levels for amphibians and reptiles appear to be the loss, degradation and fragmentation of habitat. The results echo findings for British butterflies, pointing to the possibility of common threats.

ARC hopes the results will prove invaluable for conservation. Red List categories could, for example, be used to inform revised approaches to protected site designation. The findings for common toad and adder are especially useful since they reinforce the message wide ranges may mask declines, and these species deserve greater conservation attention. The Red List assessment will be reviewed as new data emerge in future, possibly meaning some species shift category in years to come.

Substantial declines in the common toad mean the species is deemed ‘Near Threatened’ in Great Britain

As with any assessment method, care is needed when interpreting and applying Red List categories. Red Listing simply expresses extinction risk at a given spatial scale, and so other information must be used alongside or even instead of Red Lists for most conservation applications. Red Listing uses a “floor” – i.e. extinction – but for species above that level it does not usefully assess true conservation status. Even species that are substantially depleted can be assessed as “Least Concern”, as we found. This is highlighted in new research published last week, where a “Green Status of Species” is proposed to address the shortcomings of Red Lists. ARC encourages appropriate use of Red Listing in Great Britain, noting that unfortunate consequences can arise, for instance when it is used as the main criterion for legal protection as we highlighted recently.

Notwithstanding those caveats, this first Red List for Britain’s amphibians and reptiles is a significant achievement and we look forward to seeing it used to drive conservation action. ARC is thankful for the support of Natural England for this work.

The report is available at ARC’s “Technical reports” page and the full reference is:

Foster, J., Driver, D., Ward, R. & Wilkinson, J. (2021). IUCN Red List assessment of amphibians and reptiles at Great Britain and country scale. Report to Natural England. ARC report. ARC, Bournemouth.

---

Banner image: adder by Ray Hamilton