Sleepy Hollow
Throughout winter we dig out our woolly jumpers and turn on the heating, but how do Hampshire’s mammals adapt to the cold temperatures?
Winter is a difficult period for mammals as there is less natural food available and the harsh weather conditions. Mammals are warm blooded creatures that produce energy from the food they eat to keep a constant internal temperature. In some cases this is simply not possible as there is not enough natural food available to produce enough energy to keep warm. Some mammal species have overcome this problem by hibernating through the winter. Hibernation effectively allows the animal to reduce its heart rate and internal temperature in order to use less energy and survive the cold.
Before entering hibernation it is vital that the mammal eats as much food as
it can to ensure it has enough energy reserves to survive. Hibernating mammals
usually have normal periods of activity several times throughout the hibernation
which are used to eat food, drink water and excrete waste.
There are only 3 species of British mammal that truly hibernate, but which are
they?
Hedgehogs
Hedgehogs are regularly seen in urban gardens and will often hibernate in gardens if there is a suitable habitat available. The hedgehog hibernation period is from November to March but is dependant on weather conditions and food availability. During hibernation a hedgehog’s heart rate will drop from 190 to 20 beats per minutes and their internal temperature will drop from the usual 37 C to just above freezing. Hedgehogs will often stop visiting a garden in winter if there are no suitable areas for hibernation. Piles of logs and leaves in a dry area protected from the wind can provide an excellent hibernation habitat for hedgehogs.
Dormice
The
hazel dormouse has a reputation for its hibernation habits. The name dormouse is
connected with the Latin ‘dormire’, or French ‘dormir’ which means ‘to sleep’.
During the summer and autumn months hazel dormice will fatten up and prepare for
the winter by eating hazelnuts and honeysuckle berries. The dormouse hibernation
period can be anytime between October and April and takes place in an
underground nest within a tangle tree roots. Dormice often lose half of
their bodyweight during hibernation and so when they emerge in spring they feed
on willow flowers and insects to build up their fat reserves. After hibernating
dormice build nests of woven honeysuckle further up in the trees or hedges which
they then live in throughout the spring and summer.
Bats
Bats usually hibernate between November and April, and they chose their
hibernation sites very carefully, taking temperature, moisture and location into
consideration. Hibernation sites can be hollows in trees, roof spaces, caves,
cellars or even purpose built bat boxes. During hibernation bats can take as few
as 5 breaths per minute as the entire body slows down to save valuable energy.
Like most hibernating species, bats will wake up for short periods to search for
food and water and excrete waste. This uses a lot of energy and it can take 20
minutes for a bat to warm its body up enough to become active.
If you would like to find out more about the species featured in this article,
please contact Hampshire & Isle of Wight Wildlife Trust’s free wildlife
information service, WildLine on 01489 774446 or email WildLine@hwt.org.uk.