Small British Mammals: Dormice

Hazel dormouse

The general body plan of looking like a mouse or rat is one that's proven very successful for rodents; a huge number of rodent species, not all of which are closely related, broadly fit this description. Both the mouse family and the "hamster family" (which includes deer mice, pack rats, and voles, among others) are considered to be part of a larger grouping of related rodent families called the Myomorpha. This roughly translates as "mouse-like rodents" and it's a group that includes, under the most common current system, seven different families.

Historically, the Myomorpha was defined based on the structure of the jaw muscles, so that it included some animals, such as jerboas, that don't necessarily look all that much like regular mice. But modern genetic analysis has shown that this anatomic feature isn't as unique as we'd thought, and seems to have evolved at least twice, perhaps in response to a similar dietary requirement in the two different groups. As it happens, the jerboas got to stay in the "mouse-like" group (if only just), but one family of animals that manifestly do look like mice turned out to be something else entirely, and about as unrelated to true mice as it's actually possible to be among living rodent species.

Is the Dormouse an Endangered Species?

At first glance, this seems a fairly daft question. A moment's search on the internet will reveal that only is the dormouse not an endangered species, it isn't even under any significant threat of becoming one. It's about as safe as any species that doesn't specifically rely on human beings can be. There is no risk that we are going to, at any point in the foreseeable future, even come close to running out of dormice.

Look past the headlines though, and things do become a little more complicated. No, the dormouse is not an endangered species, but its population is under threat in certain parts of its range, particularly in the northwest. Some of these populations are isolated from the main bulk of the species in mainland Europe by the presence of various seas, and perhaps the most obvious of those is the British population. Since this population lives on a (relatively) northerly island, and since there are, apparently, risks to the dormouse in the north of its range, it is, in fact, reasonable to ask whether or not the dormouse is an endangered species in Britain.