Dormice are nocturnal (active at night) and use their large eyes, long whiskers and excellent sense of smell to find their way about. They are much more agile than other mice, spending a lot of time climbing around bushes and trees, rarely coming down to the ground. Among the branches they search for flowers, pollen, fruit, nuts and insects. Early in the spring, hazel catkins and spring flowers provide a nutritious food and the dormouse's whiskers carry pollen from flower to flower which helps pollination. Fruits and nuts become available as summer progresses into autumn so the dormouse needs a habitat containing a good variety of plant species to ensure a continuous supply of food.
During the day, dormice sleep in a nest, often in a hollow tree branch or old bird's nest-box, several feet off the ground. A nest is domed in shape about 15cm (6in) across, and to build it the dormouse shreds honeysuckle bark, weaves it into a ball and may surround it with leaves. The dormouse usually forages no more than 70 metres from its nest.
An old English name for the dormouse is 'the sleeper'; it is the only British rodent which hibernates, and it does this from about mid-October until April or May. Before hibernation, a dormouse eats as much as it can in order to build up a fat store.
It makes a nest deep in a hedge or on the ground, lines it with grass, wool, leaves etc, and prepares a little store of food in case it wakes up during a warm spell. Then it curls up into a tight ball and goes to sleep.
The body temperature drops to that of its surroundings and its heart and breathing rate are often reduced by 90% or more - this saves energy and allows the dormouse to survive for about 6 months on its body fat. As the weather warms up, a hibernating dormouse's body temperature begins to rise and it takes about 20 minutes to become fully awake.
Dormice usually have one, sometimes two, litters a year, between May and September. There are about 4 young, born blind and naked. They soon grow grey fur, but by the time they leave the nest at 4 weeks old they are almost the colour of the adults. The breeding rate depends very much on the weather. In a year when food is scarce or when bad weather has prolonged hibernation or restricted the dormouse's feeding time, most litters may not be produced until August, September or even October. In these cases, the young dormice may not be able to build up enough fat to survive the winter.Read More: Dormouse Problems