New research published in _Scientific Reports_ suggests that Britain's hazel dormice are experiencing changes in their body mass due to climate change. A 30-year study of data from England and Wales indicates that dormice are emerging from hibernation lighter in May and June, potentially because smaller bodies lose heat more effectively in warmer conditions or due to increased activity during hibernation. Conversely, their weight before hibernation has increased, possibly linked to greater food availability from increased summer rainfall. The study, a collaboration between the University of Exeter, Bat Conservation Trust, and PTES, also found that dormice in woodlands with denser, taller hedgerows were heavier. These findings underscore the complex impacts of climate change and habitat quality on this endangered species, which has seen a 70% decline since 2000.