Winters are a trying time for wildlife. With freezing temperatures, scarce food sources and difficulty in camouflaging, it isn’t easy to get by. Different animals use different strategies to survive and make it through these harsh conditions. Here are a few tricks that help some creatures weather even the coldest of winters.
Moving on: Migration
Without question, the best way to survive a winter is to not be around for it. Several animals plan long and arduous journeys to escape the cold season. They use environmental cues to migrate to warmer locales and return when the climate is more favourable. Monarch butterflies for example make one of the most spectacular journeys across North America to escape harsh winters, migrating from the United States and Southern Canada to Mexico.
The Arctic tern covers 44,000 miles travelling pole to pole just so it can enjoy continuous summer. It escapes the cold winter in Greenland in the North and travels to Antarctica to enjoy summer there before returning to the Arctic for summer up North.
Going under: Subnivean climate
As snow gathers on the ground, creating a white and inhospitable landscape, it also provides a home for several small mammals. Mice, shrews, squirrels and voles live in a safe and insulated habitat under the snow in ‘subnivean climate’. Subnivean is a word derived from Latin that translates to ‘under (sub) snow (nives)’.
As igloos or snow caves provide protection from the cold, the temperatures in these under-the-snow habitats remain stable at around 32ºC keeping animals warm and protected from winter winds. The animals create tunnel pathways connecting sources of food and sleeping areas. Some animals have their stock of winter food they’ve saved up, while other foods such as seeds, barks and roots are more easily available under the snow in the winter.
Getting closer: huddling
Huddling together is a time tested technique used by several animals in the winter. Being close to one another helps them increase their body temperatures so they can better cope with cold temperatures. Emperor penguins in Antarctica are subject to some of the coldest average temperatures on earth (-30ºC) 22ºF and cold winds that can reach up to 200kph.
Male penguins look after the eggs for months in the biting cold. They cope with these conditions by huddling together in groups of thousands of penguins. The birds circulate so that penguins on the periphery have an opportunity to get warm. Other animals that huddle up to increase surface area, and therefore temperature, include sea lions and walruses.
In deep sleep: Hibernation
Some animals decide to sleep through the cold to survive it. This means they remain inactive; their body temperatures, breathing, metabolism and heart rates are greatly reduced during this period to help them conserve their energy. Animals eat generously before hibernating so as to develop fat deposits to rely on during the winter. Some bats, marsupials, rodents, snails, insects, birds and even turtles are among other animals known to hibernate.
Some species of bears are known to enter a period of winter inactivity. However, they are not ‘true hibernators’ as their body temperatures only drop by a few degrees and they can also wake up at will without much difficulty. Hedgehogs are some other animals that hibernate through the winter. Marmots also sleep through eight months each year and spend the summer months reproducing and eating to double their body mass for the next winter. However, animals do wake up during their hibernation. Hedgehogs wake up every week or 10 days, while some bats are up once in 20 days before getting back to deep sleep.
Changing with the winter wind: Adaptation
Different species also make certain alterations and adjustments to cope with winter temperatures. The arctic reindeer’s hooves shrink in the winter to help it cope with the snow. The animals also change their eye colour from gold to blue in the winter. This helps them capture more light in the dark arctic winter. Several birds and mammals also experience changes in their feathers and fur to suit the season.
Ermines that have chocolate brown coats during the summers change to being completely white to help them camouflage in the snow and prey on rodents more easily. Another example of winter adaptation is the white tailed deer, which produces different digestive enzymes in the winter to cope with the tougher food sources of the season.
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