Hazel Dormouse, Muscardinus avellanarius, is one the rarest, and best loved, of the UK’s rodents. They are most famous for their mini hibernations, which they do when food is scarce or the weather is bad. They do this to help save energy and this mini hibernation is called torpor. They are often pictured curled up sleeping, in torpor, but as a small rodent, they are actually very active and can scamper rapidly through the treetops, where they live. They are an arboreal, or treetop, species.

Although they are called the hazel dormouse, they, in fact, eat a whole range of things depending on the time of year. Hazel nuts do play and important part in their diets in autumn, helping them to build up the fat reserves they need to survive the winter, as they hibernate from November to May. The rest of the year they eat leaf and flower buds, invertebrates, caterpillars or aphids, fruit and seeds of many woodland and woodlands edge plants, especially bramble. This varied diet is one of the reasons for their rarity as they need a big area to find all the food they need, so their population density is low.

One of the best ways to look for dormouse is to look for chewed hazel nut shells in autumn and winter. They open their nuts in a very specific, and therefore identifiable way. A hazel nut opened by a dormouse has an almost perfectly circular hole, with the hole crossing onto the ‘scar’ at the top of the nut. Because they gnaw the hole with a twisting motion, the tooth marks they leave on the shell are very distinctive, making the edge look almost like a piece of braided (plated) string