Climate & Environment

Dormouse Numbers Rise in England and Wales Amid Warmer Weather

By Today News Hours Editorial Desk

New data indicates that hazel dormouse populations in England and Wales increased by almost 10% between 2020 and 2025, a period that coincided with warmer springs and summers. The National Dormouse Monitoring Programme, run by the conservation charity People’s Trust for Endangered Species (PTES), has tracked sites in the two countries since 1998. Since 2000, dormouse numbers had fallen by nearly 60%, an average annual decline of 3.5%. The recent uptick, however, suggests the long‑term downward trend may be reversing, although researchers note considerable uncertainty around the estimate.

Ian White, a co‑author of the report and PTES representative, described the upturn as “welcome good news” that offers “cautious optimism,” but warned that populations remain almost 60% lower than in 2000. The improvement aligns with a period of warmer, drier-than‑average springs and summers. Scientists believe these conditions may reduce the dormice’s need for torpor—a short period of deep sleep used to conserve energy during cold, wet weather or food shortages—allowing more time for feeding and breeding.

Dr Charlotte Armitage, an ecologist involved in the survey, said that while warmer summer conditions are likely to give the animals more energy to reproduce and raise additional litters, significant uncertainties remain. She highlighted the need for further research on how dormice will respond to warmer, wetter winters and emphasized that protecting their woodland and hedgerow habitats, conducting more climate‑change studies, and implementing effective woodland management remain essential for the species’ long‑term survival.

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. Large areas of woodland have been lost, and native populations have disappeared from around 20 English counties. The recent increase offers a rare piece of good news for this beloved mammal, but conservationists caution that continued habitat protection is crucial.