UK Dormouse Population Shows Signs of Recovery Amid Warm Weather
Britain's hazel dormouse population has increased by nearly 10% in recent years, offering hope after decades of steep decline.
At a glance
- The UK hazel dormouse population increased by nearly 10% between 2020 and 2025, reversing part of a long-term decline.
- Warmer, drier springs and summers likely reduce the dormice's need for energy-saving torpor, boosting breeding.
- Despite the recent rise, overall numbers are still almost 60% lower than they were in 2000, highlighting ongoing conservation needs.
The UK's only native species of dormouse, the hazel dormouse, has shown a surprising population increase of nearly 10% between 2020 and 2025, offering a rare piece of positive news for conservationists after decades of decline. The survey, which monitors populations in England and Wales, attributes this promising upturn to warmer, drier spring and summer weather.
Historically widespread across the country, hazel dormice have suffered heavily from habitat loss as woodlands and hedgerows disappeared. They are now largely restricted to southern England and parts of Wales, having vanished from roughly twenty English counties. Since monitoring began in 1998, the National Dormouse Monitoring Programme recorded a steep drop of almost 60% in the rodent population since the year 2000, representing an average annual decline of 3.5%.
Researchers suspect that warmer summers are reducing the need for dormice to enter torpor, a state of deep sleep they use to conserve energy during cold or wet periods when food is scarce. By spending less time in torpor, the small rodents may have more energy available for feeding, breeding, and raising multiple litters.
Despite the positive trend, scientists urge caution. Ian White of the People's Trust for Endangered Species described the upturn as welcome but stressed that overall populations remain nearly 60% lower than they were in 2000. Ecologist Dr. Charlotte Armitage added that significant uncertainties remain, particularly regarding how the species will cope with warmer, wetter winters under climate change.
Experts emphasize that the recent uptick does not diminish the critical need to protect woodland and hedgerow habitats. Continued research, effective habitat management, and conservation efforts remain vital to securing the long-term survival of the sleepy rodent in the UK.
Source: BBC Science
Questions and answers
- By how much has the UK dormouse population recently increased?
- Between 2020 and 2025, the UK hazel dormouse population showed an increase of almost 10%, though scientists note there is considerable uncertainty around this estimate.
- Why are warmer summers thought to help dormice?
- Warmer summer conditions are believed to reduce the dormice's need for torpor, a deep sleep used to save energy, leaving them with more energy for feeding and breeding.
- How much has the dormouse population declined historically?
- Since 2000, the hazel dormouse population in England and Wales has declined by almost 60%, averaging a 3.5% annual drop, leaving them confined to southern England and parts of Wales.
