Like some other species mentioned in the Woodlands blog, it is thought that the numbers of the hazel (or common) dormouse have declined dramatically over the last 100 years. This has been associated with the loss of woodlands and hedgerows, and changes in their management. The dormouse is to be found in deciduous woods mainly in the southern counties of England, though there are records of the dormouse along the Welsh Borders and parts of Wales.

They forage for food in trees and hazel thickets, feeding on flowers, fruits (e.g. blackberries), insects (aphids, caterpillars) and mature nuts. Their diet changes as spring becomes summer, and their habitat must offer a variety of woody shrub and tree species to ensure a constant supply of food. Honeysuckle, oak, bramble and hazel are important sources of food to them.

The chances of seeing a dormouse are small as they are nocturnal, but you might find signs of their presence in the form of chewed hazelnuts. They open up the nuts by making a small, round hole on one side of the nut. This characteristic pattern of opening hazel nuts was used in the Great Nut Hunt (2001) which provided a lot of information on the distribution of the dormouse in the UK.

For many months of the year, the dormouse is ‘asleep’. With the arrival of the first frosts (which can be in October) they hibernate and do not generally awaken until April or May. They roll up into a ball and their body temperature drops close to that of their surroundings. Their heart and breathing rate drop dramatically, as does their metabolism. The body uses fat stores that have (hopefully) accumulated over the summer months. Adults weigh about 17 to 20g though at the start of hibernation they may weigh up to 40g.

Dormice can live for up to 5 years, which is significantly longer than many other small rodents. They can have one or two litters a year, with perhaps 4 young per litter. However, they are sensitive to bad weather, which can result in a litter being produced late in the season; this, in turn, may mean that the young may not lay down sufficient fat reserves to see them through the winter.

The Mammals Trust UK has been re-introducing the dormouse to selected sites, which match certain criteria. If you are interested in offering a home to some, then visit The Mammal Trust's website and download the form to see exactly what is needed.

Photo © John Robinson