One of Britain's rarest mammals has become locally extinct from Northumberland in the last four years, according to a new study.

Hazel dormice are small, native rodents with soft caramel-coloured fur, a furry tail and big black eyes. They are considered a key indicator species, meaning that where there are dormice there is usually wider animal and plant diversity too.

However, they've experienced a historic and "catastrophic" decline according to the People's Trust for Endangered Species. Habitat loss, degradation, poor management of Britain's woodlands and hedgerows and climate change are cited as the main reasons for the dormouse's decline.

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It has been lost from 20 English counties since the Victorian times, and their numbers have declined by a staggering 70% since 2000, with Northumberland one of three counties where the charismatic rodents have been lost since 2019.

A report published by the PTES, named The State of Britain's Dormice 2023, has called for dormice to be classified as 'endangered' on the IUCN Red List rather than 'vulnerable', in the hope of making them a higher priority species which could result in increased targeted conservation efforts. These could help in reversing their chronic decline.

Ian White, dormouse and training officer at People's Trust for Endangered species, said: "The wealth of data from our monitoring programme gives a unique insight into how dormice are faring and contributes to major reports such as the recent State of Nature, which drives wider conservation efforts. If the decline continues at the same rate, in another 30 years dormouse populations will have fallen by 94% since 2000, which we simply cannot let happen.”

"Armed with the latest facts we need to continue pushing for dormice to urgently be reclassified as ‘Endangered’ on the IUCN Red List, and we need to start rolling-out more footprint tunnel surveys (as well as nest box checks) in non-woodland habitats such as hedgerows, scrub, roadside and railway verges. Footprint tunnels will allow us to gain a more complete picture of how dormice are faring across multiple habitats rather than just woodlands.

"Once we have data from non-woodland sites too, we can target conservation efforts more widely which we hope will start to reverse the decline."

Despite the statistics, there is a glimmer of hope for dormice, with PTES managing the annual dormouse reintroduction programme since 1993. 1,112 hazel dormice have been release into 25 different woodlands in 13 counties across the UK, which has ensured the presence of the creatures in six English counties they had previously been lost from, mostly in Northern England and the Midlands.

However, Northumberland is not one of these counties.

Ian White concluded: "Dormice continue to face an uncertain future as our climate and countryside change. Declines on this scale cannot be fixed overnight, so it will take time before we see if our conservation work is effective.

"We know what works for dormice, but we urgently need increased funding to implement this nationally. Hope is not lost as reintroductions, monitoring, research and landscape projects offer a lifeline - and some populations appear to be thriving - but we need to do everything we can on a much bigger scale to prevent the worst case from happening."