Britain's dormouse population shows modest increase

The National Dormouse Monitoring Programme, run by the People's Trust for Endangered Species, said the hazel dormouse population in Britain grew by almost 10% between 2020 and 2025, hinting at a possible reversal of a long‑term decline.

The hazel dormouse, the only dormouse species in the UK, was once widespread but is now largely confined to southern England and parts of Wales, having disappeared from around 20 English counties as woodland loss accelerated. Monitoring of sites in England and Wales has been underway since 1998. Figures indicate that since 2000 the species’ numbers have fallen by nearly 60%, an average annual drop of 3.5%.

The recent rise coincides with warmer, drier‑than‑average springs and summers, though researchers stress considerable uncertainty around the estimate. Report co‑author Ian White of PTES described the upturn as "welcome good news" and said it gives grounds for "cautious optimism", but added: "We mustn't lose sight of the bigger picture: populations remain almost 60% lower than they were in 2000."