During the winter months, temperatures drop to below freezing in some parts of South Africa. Us humans put on layers of clothing, hide indoors and keep warm next to the fireplace, but what do the animals do? By Fran Siebrits
If you have gone camping in the Tankwa Karoo National Park in winter, you will know how icy it can get outside. While we wrap up and huddle around the fire while complaining how cold it is, the animals seem to cope just fine. Each one has a special adaptation to help them survive the colder months.
Sleep and hibernate
One way mammals survive winter is by hibernating. They go into a deep sleep where their heart beat and breathing slows down, their body cools down, and they don’t need to eat food or drink water because of this decreased metabolism.
Because there is less food available in winter, hibernating is therefore a way to use up the body’s fat at a much slower rate. Animals that hibernate know to put on extra weight in summer and autumn, when the food is available, to have enough fat stored for winter.
Some mice and birds only use this deep sleep stage for a few days or even just a few hours on an extremely cold night. This is known as torpor and the body temperature drops, but not as much as in hibernation.
Leave and migrate
Some birds migrate to warmer areas for the winter months; but other animals also move away to warmer areas to wait out the winter. Although they don’t cover extensive distances, some insects migrate. Mammals such as certain bat and whale species travel in search of food each winter. Even earthworms migrate, heading down into the soil where it is warmer during these chilly months.
Remain and adapt
Then there are animals that don’t move away but don’t hibernate either. To remain active during winter they adapt their bodies or behaviour. Food is another consideration during this time as there is generally less available. Most carnivores therefore assume a larger home range to assure an adequate food source while other animals simply store food for the winter months.
To keep warm, many mammals such as rabbits grow extra thicker fur. The black-backed jackal, for example, also makes use of a thick under-coat in winter. Acting as a temporary jersey when it is cold, this extra fur coat is shed in spring.
Birds that don’t migrate also grow an extra under-garment. These winter feathers, obvious on owls and hawks in particular, keep them warm during the cold months. They are even able to fluff-up their feathers to trap in heat generated by their bodies, thereby insulating themselves. Some antelope species use this insulation method as well by raising the hairs on their body to trap heat.
Squirrels are probably the most organised when it comes to winter. They know food is limited at this time of year and therefore gather extra in the autumn and store it to eat in winter. In an attempt to stay warm, squirrels may also huddle close together.
Whatever the group, all animals are sensitive to and aware of the elements. When the sun is out, they make the most of it and you can often see animals ‘sunning themselves’. They angle their bodies so that the largest surface area is exposed to the sun i.e. they stand at right angles to the sun so that their sides gather the warmth. In the hotter months, the opposite is true and they will stand head- or tail-on exposing the least amount of surface area to the sun.