BBC Wildlife - UK (2019-12)

December 2019 BBC Wildlife 67

Who doesn’t hibernate?

There are only three types

of animals in Britain that are

true hibernators: dormice,

hedgehogs and bats. It isn’t

a very long list and there are

some omissions that might

surprise people – mice and

voles, for example, are active

and alert all winter, and

squirrels don’t just stay awake,

they breed in January. Shrews

should be perfect candidates

• small and fast-moving, with
  bodies that lose heat rapidly,
  a high metabolic rate and
  an insectivorous diet. In the
  winter, they sleep for longer,
  hunt mostly underground, yet
  rarely (if ever, depending on
  the species) go torpid and they
  don’t hibernate. In the autumn,
  all the breeding adults die o,

so that the year’s youngsters

are left to carry on the

generations. At the other end

of the scale, the badger enters

into a state known as winter

lethargy. Between November

and February, it spends most

of its time underground,

puts on weight and its body

temperature may drop. But

that isn’t hibernation.

While extreme

conditions of winter

cold are dangerous, so

is unusual warming.