Live 24-Seven - Preserving Wildlife
Bearded tit. Photo: Amy Lewis Wildlife in Winter
Denis Jackson, people and wildlife manager with Gwent Wildlife Trust considers some well-tested and sometimes quite surprising survival techniques.
We’re now entering the time of year when conditions outside can be at their most challenging. The transition into winter can feel sudden to us Northern European humans as we scurry from home, to car, to work and back again – especially now we have changed our clocks! But for our animals, birds and insects the changing seasons are more incremental and result in the deployment of a number of well-rehearsed strategies designed to maximise the chances of getting through to the spring.
Much of our wildlife will just tough it out – perhaps growing a winter coat or putting on a bit of extra fat to beat the cold. Some will migrate or opt for hibernation, the Big Sleep. For insects, some will over-winter but many will die and it’s left to the eggs and pupae, often buried in the ground or drilled into rotting wood, to keep the species going in the following year. The mullein moth, for example, can spend four years as a pupae − way longer that the few weeks spent as a flying adult.
Gwent Wildlife Trust Tel. 01600 740600
www.gwentwildlife.org
You’ll be familiar with some of those that just tough it out. Many garden birds, the fox and the rabbits that leave distinctive trails of footprints in the snow for us to find on a winter’s morning
Hedgehog. Photo: North East Wildlife
all adopt this strategy. Many of these creatures will, unfortunately, fail to survive the most extreme periods but enough usually make it through to keep the population healthy.
Many of the animals we might think of as hibernators are actually toughing it out, too, with periods of activity interspersed with the odd serious snooze. Squirrels, badgers, mice and shrews will sleep for days at a time through a cold snap until a spell of warmer weather allows them to get out and top up their energy reserves.
The bearded tit has an unusual way of dealing with winter. These birds spend the whole year in British reed beds, feeding on insects. Their digestive system is adapted to make the most of that food. Come late autumn though, insects are in short supply and rather than migrating, this bird undergoes an amazing transformation − it changes its gut! The gizzard, a sort of stomach, thickens and can double in weight. This, combined with swallowing coarse grit, allows what was an insect-eating bird to efficiently digest seeds and fruit. In the spring, the gizzard returns to its original condition.
When we think of hibernation, most of us think of mammals. There are actually only three British mammals which truly hibernate − dormice, hedgehogs and all 17 of our bats. Hibernation in mammals is an amazing thing. During autumn, these animals will have been feeding furiously to increase their body fat – the energy store they will use to get them through the winter. As the temperature starts to fall, they’ll start looking for the ‘right spot’…somewhere dry, and, most importantly, somewhere with reasonably constant temperature and humidity. If any of these animals suddenly experience warmer conditions, they might wake up prematurely, burning up their precious fat at a higher rate for a while, which could well leave them with insufficient energy to get through the rest of the winter.
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