Dormice are famous for being sleepy. Their hibernation may last up to six months if the outside temperature remains cold. To accomplish this feat they store body fat during the summer months. Dormice are also unique among rodents in their lack of a cecum, that is the part of the gut used to ferment vegetable matter. These small, agile creatures are most at home in woodland, where they are well adapted to climbing trees. With a few exceptions in Africa and Asia, most of the 30 species of dormice live in Europe. The hazel dormouse is the only one native to the United Kingdom. The edible dormouse was introduced to Hertfordshire in the early 1900s.