The Delicate World of Dormice

With big eyes, golden fur, and enviable sleep habits, it's easy to see why the Hazel Dormouse is one of the cutest animals in Welsh forests.  Unfortunately, these charismatic creatures are in decline across the UK and are surveyed across the UK to monitor numbers.

In this blog, NRW Land Management Officer, Jane Morgan tells us all about the vital work she does to survey Dormouse nest boxes in woodlands around Machynlleth and the Dyfi, and how this work supports their conservation.

About These Charismatic Little Creatures

Dormice are truly charming animals. Their big, dark eyes make them look curious and alert, and make them perfectly adapted for their nocturnal lives. The coat of an adult dormouse is a beautiful golden brown; soft and velvety to the touch.

These little acrobats are about the size of a human thumb when fully grown, weighing only around 17-19 grams during the summer and can increase their body weight to over 30 grams before hibernation. Newborn dormice are known as Pinks. As you might suspect, they are pink, tiny, hairless, and have closed eyes. As they grow, they open their eyes and develop soft, greyish fur before eventually maturing into their golden coats.

Dormice are expert climbers, thanks to their feet that are splayed at 30 degrees and their furred and bushy tail to keep balance. These adaptations allow them to navigate the tree canopy with ease. They spend much of their waking time feeding in trees and building their summer nests in tree cavities, although the height of the nest depends upon the habitat type and can often be found at around chest height.

One of the most charming aspects of dormice is their state of torpor. This is like sleep, and we sometimes find them in this state during our surveys. They remain peacefully asleep as we gently handle them, sometimes even snoring softly!

Sadly, dormice are very vulnerable. Their numbers have dropped by 70% between 2000 and 2022, according to the State of Britain’s Dormice report. This motivates me to collect all the information that I can, and to make sure that we use the information for practical conservation measures.

Why Monitoring Dormice Matters

Dormice are protected under European law, meaning they need extra care. Their habitats must be managed carefully to ensure they have what they need to thrive. With my NRW colleagues, Wildlife Trust colleagues and volunteers, I monitor dormouse nest boxes twice a year: once in May/June, before they breed, and again in September/October, after the babies are born. These surveys are crucial for several reasons:

• Better Forest Management: The data from our surveys helps our colleagues who plan forest activities, such as tree felling and planting, to work during times of least impact and to apply best practice to reduce damage to dormice and their habitat.

• National Dormouse Monitoring Program: We share our results with this UK-wide program managed by the People’s Trust for Endangered Species. This helps build a big picture of dormice status and needs.

• Raising Awareness: Monitoring dormice helps us educate people about their plight and why they need our help.

The Gentle Survey Process

Surveying dormice is a delicate task. Dormice are nocturnal and can spend much of their days in a state of torpor. We conduct our surveys before midday to try and catch them in their summer nests whilst they are still snoozing.

Each nest box is carefully opened, and any dormice inside are gently lifted out, counted, and their sex is noted. We also check the breeding condition of females and weigh each dormouse. If we encounter pinks, then we do not disturb the nest box any further.

This is a specialist job that I can only do because I have a dormouse licence. It takes practice with an experienced instructor to get a licence and it means that I know how to handle them with care. Handling with care is especially important because dormice can shed a portion of the tail skin easily if handled incorrectly or held by the tail.

The Challenges Dormice Face

Dormice build their breeding nests high in tree cavities or in the understorey, and their hibernating nests closer to the ground.

They need a variety of foods, including hazel, honeysuckle, brambles, hawthorn, and blackthorn, as well as aphids. Connected habitats are crucial for their survival, allowing them to travel through the tree canopy to find food and mates. That’s one reason why having diverse and well-planned forests are so important; it provides the food, homes, and space that they need, as well as their ‘transport’ networks high in the trees.

One of the biggest threats to dormice is the climate crisis. Warmer temperatures can cause them to wake from hibernation early, when there is no food available, leading to starvation.

A Success Story

One of my most rewarding experiences involved a forest felling project with my NRW colleagues. An area of forest made up of mainly larch trees needed to be clear felled; this could have posed a risk to dormice, but also an opportunity. By carefully planning the felling and replanting with a diverse range of tree species beneficial to dormice, we started the transformation of the area.

Even so, out of 40 nest boxes in an area that I surveyed regularly, there was only one large male dormouse for 18 months.

A year or two after the new trees were planted, I found eight dormice in the nest box scheme; the lonely dormouse was no longer alone! This is just one example, and we don’t always see such rapid improvements, but it’s an important success story that shows how thoughtful conservation efforts based on data can have a positive impact on dormice.

Why Dormice Are Special

Dormice are more than just cute and fluffy; they play an important role in the ecosystem. They indicate a healthy environment, and their presence – or absence - tells us a lot about the state of our forests. They are also incredibly resilient, capable of surviving tough conditions if given the right support.

Working with dormice is one of my favourite parts of my job. I see my role as giving a voice to these voiceless creatures, making sure their needs are considered in forest management and conservation efforts.

How You Can Help

Everyone can help with dormouse conservation. Whether it’s planting dormouse-friendly trees, supporting conservation organizations, or simply spreading the word about their plight, every action counts. By working together, we can ensure these charming creatures continue to grace our forests and hedgerows for generations to come.

About Jane

Jane Morgan is a Land Management Officer for NRW, working in the conservation of dormice. With a deep passion for wildlife and a commitment to protecting vulnerable species, Jane's work involves monitoring dormouse populations and ensuring that forest management practices support their survival.

Her work at NRW also takes her beyond dormice. Some of her other responsibilities include surveying stands of trees before felling or thinning to see if there are nests, nesting areas, dens, setts, or heritage features that need to be considered during the forestry operations. She manages work on Sites of Special Scientific Interest and Scheduled Monuments within the Welsh Government Woodland Estate and works to remove Invasive Non-Native Species from ancient woodland sites.