Dormice in the Woodland Habitat
Not everyone is a fan of rodents, but you might find yourself making an exception for the undeniably cute hazel dormouse – Muscardinus avellanarius (Family: Gliridae).
If you have been lucky enough to spot this beautifully big-eyed, golden creature in Ireland, then you will have noticed a particularly distinctive feature, their long, furry tail! Their beautiful bushy tails can be between 5.7cm and 6.8cm long and help keep these arboreal creatures balanced as they search for pollen, flowers, nuts, fruits and insects in habitats such as woodlands and hedgerows.
Honeysuckle, bramble and oak are an important source of food for dormice too. These agile climbers also make use of their rotating ankles, gripping the branches as the climb. Dormice are nocturnal creatures and make use of a technique called “whisking” which helps them find their way in the dark and navigate gaps between branches for example. Whisking involves vibrating their whiskers in front of them to guide their foot placement and explore their environments in the dark of the night!
Dormice are not native to Ireland, but there have been sightings in Kildare, where there now appears to be a small, local population. It has been suggested that they were introduced in Ireland by accident while sleeping in hay transported in a horsebox from England, where they are native. This would not be a surprise as dormice are often depicted as sleepy animals as they spend so much of their time sleeping and in hibernation. In fact, they can spend up to 75% of their lives sleeping! They also undergo a process called ‘torpor’ during periods when food is scarce, or conditions are cold or wet. Torpor is a state of reduced physiological activity in an animal, similar to hibernation and it enable the dormouse to conserve energy and survive. In the UK, dormice will typically hibernate between October and May underneath hedgerows and in nests on the forest floor, which of course can make them vulnerable to predators like badgers. It is considered that one of the biggest threats to dormice is surviving through the Winter.
Dormice usually build their own nests from branches such as honeysuckle, layered with grass and leaves, but have also been found sleeping in old bird nests! It is in these nests that the females will give birth to, on average, 4-5 young who will remain with their mother until they are juveniles (between six and eight weeks). Females will primarily only produce one litter of offspring each year, in July/August shortly before hibernation begins again. Baby dormice are pale grey in colour and are born blind. However, by the time they are eighteen days old, they can see. The pale grey colouration remains until they reach a year old when it begins to turn that lovely golden-brown colour, by which time they are also sexually mature.
Dormice preferred habitat is in woody vegetation, such as managed woodland, scrubs, hedgerows and have also been found in conifer plantations. Dormice like to keep safe under the forest canopy and you will rarely see a dormouse scarpering along the ground, as it makes them incredibly vulnerable to predators such as owls, grey squirrels and cats for example. Sadly, their habitat in the UK is under threat, as factors such as the removal of hedgerows, changes in countryside management practices, loss of woodlands, habitat fragmentation and climate change wreak havoc on their populations. Changes in weather and climate mean that foraging for food has become more difficult for the dormouse and warmer winters interrupt their hibernation causing them to wake when food availability is lower. The stress has proven quite too much in some regions where the dormouse is now completely extinct in parts of north and east England.
Dormice are an endangered species and as a result, are protected under the EU Habitats Directive. In fact, in the UK it is a crime to harm them and a person may be fined up to £5,000 and go to prison for up to six months for damaging their habitats, injuring or disturbing a hazel dormouse. There are ongoing conservation efforts to save this species including the management of existing habitats in a dormouse-friendly way. Connecting fragmented habitats through the reconstruction of hedgerows, wildlife corridors and dormouse bridges are fundamental in achieving this goal.
If you happen to spot any dormice, please submit your observations to the National Biodiversity Centre at : https://www.biodiversityireland.ie/
Interesting facts about Dormice:
- In Victorian England, school children would trade dormice in the school yard
- The hazel dormouse has been present in Britain since at least the last Ice Age
- Beatrix Potter had a pet dormouse named Xarifa
- The dormouse gained popularity through Lewis Carroll’s Alice’s Adventures in Wonderland where he appears sleepily at the never ending, Mad Hatter’s tea party
Written by Natalie Cunningham
Hazel (or Common) dormouse – People’s Trust for Endangered Species (ptes.org)
BBC Two – Autumnwatch, 2015, Autumnwatch Day Four, The adorable dormouse
The dormouse makes first appearance in Ireland (irishtimes.com)
Hazel dormouse | The Wildlife Trusts
(PDF) Distribution of the non-native Hazel Dormouse (Muscardinus avellanarius) in Ireland (researchgate.net)
Dormice: Britain’s sleepiest, and most charming little creatures (countrylife.co.uk)
11 fascinating facts about the hazel dormouse – Country Life
Hazel Dormouse (Muscardinus avellanarius) – Woodland Trust