Bats, Dormice and Hedgehogs

This question was last asked in Week 5 of the 2018–19 season (13 November 2018 – set by the Sutton Club!)

There are 18 species of bat native to the UK, of which the commonest and smallest is the common pipistrelle and the largest is the noctule. The pipistrelle has a body length of 35 mm and weighs about as much as a 20p coin; and even the noctule, with a body length of 75 mm, is small enough to fit into the palm of your hand. For more information on British bats, click here.

There are actually two species of pipistrelle that are native to the UK. Nathusius's pipistrelle, to quote bats.co.uk, is "A previous migrant species, [which] has only been classed as a resident species since 1997."

The Live Science website says that "Not all bats hibernate, but those that do usually live at high latitudes where insect prey becomes scarce during cold months." The Landmark Practice (a Bristol–based environmental consultancy) says that "Like some other British mammals, such as dormouse and hedgehog, bats become torpid and/or hibernate over the winter months (usually between October and March/April)." Rentokil (boo!) notes that the pipistrelle and the noctule are two species that do hibernate.

There are 29 species of dormouse, but only the hazel dormouse is native to Great Britain. Wikipedia notes that dormice are "particularly known for their long periods of hibernation."

Note that dormice are not mice. The dormouse family, Gliridae, belongs to the suborder Sciuromorpha, which also includes squirrels; mice belong to the family Muridae, which is a direct branch of the order Rodentia (rodents) – in other words, there is no suborder.

There are 17 species of hedgehog altogether, but as far as I can ascertain, we have only one in the UK: the European variety. According to Wikipedia: "All wild hedgehogs can hibernate, though not all do, depending on temperature, species, and abundance of food." Elsewhere, Wikipedia singles out the European hedgehog as an example of an "obligate hibernator", which is an animal that "spontaneously, and annually, enter[s] hibernation regardless of ambient temperature and access to food."