Anyone walking in the forest in winter may notice: it is dead quiet in the forest. And that is not without reason. Forest animals and other wild animals have all kinds of strategies to get through the winter as efficiently as possible. From hibernation to adapting the entire gastrointestinal system. It can all be found in Drenthe’s nature.
The most famous example of animal ways to survive the winter is hibernation, Aaldrik Pot explains. Pot is an ecology forester for Staatsbosbeheer in the Heart of Drenthe. “Of the animals that occur in Drenthe, only hedgehogs and bats hibernate.”
Both animal species retreat to places where the temperature is constant. Hedgehogs are out of action the longest. “Under the influence of day length and temperature, their heart rate and blood pressure decrease and they actually put their entire metabolism on the back burner. Then they lie in a special hedgehog house or under very thick layers of leaves. Bats also hibernate, but they also wake up sometimes. Then they fly for a while,” says Pot.
In hedgehogs, waking up costs so much energy that premature awakening must be prevented. “For example, if you have a very warm period in February, after which it becomes very cold again, this can be disastrous for these types of animals.”
“When it gets colder again, you won’t actually be able to fall asleep again,” says Pot. “The moment such a body is completely started up, it takes a lot of energy.” Moreover, at those times there is often not enough food available to strengthen yourself.
Dormice also hibernate, but they only occur in South Limburg, Pot explains.
The animals that live in Drenthe’s nature have a whole range of ways in which they prepare for the cold and winter. “For example, badgers often close the pipes of their castle. This shows that cold is approaching. They also build up a fat supply so that they can get through the winter in this way. Or think of butterflies that disappear into the ground as pupae. The whole phenomenon of bird migration exists because birds cannot find insects and migrate to Africa in the winter.”
Bearded birds, birds that live in reed marshes, undergo a very special physical transformation. “They can adapt their gastrointestinal tract. In the summer half of the year they eat insects, in the winter half of the year they switch to seeds.”
And in general, animals start to rest more as soon as winter comes. “Those animals know: if I now use energy to look for food, I might use more energy than I can find in food.”
The fact that the animals take a step back when winter comes is clearly noticeable in the forest, says Pot. “You don’t see much of it, but you notice that it is much quieter. Singing also costs energy and there is no reason for birds to sing. They do not have to defend territory and they do not have to conquer a female.”
Although, there remain exceptions to the rule, Pot explains. “The robins think a little differently about that. They do sing in the winter, because they also defend their territory.”