The recent stretch of cold weather has been a shock to many of us after the great weather we enjoyed all fall. When you combine very cold weather with things such as power outages it doesn’t take long for us to realize that dealing with extremely cold temperature can be a real challenge.
Fortunately our struggles to stay warm are usually only of short duration, but it makes you wonder how wildlife cope with the double challenge of staying warm while also searching for food. To deal with this challenge local wildlife has developed a variety of strategies which ensures their survival.
Some animals, such as birds, deal with cold weather by leaving and heading to warmer climates. This ensures they are warm and have access to food such as insects. Birds that remain have strategies ranging from growing more feathers to catching food.
Other animals survive by sleeping through winter. Groundhogs, along with bats, are the only true hibernators we have in Nova Scotia. While black bears undergo a type of hibernation it differs from the real thing. True hibernators reduce their metabolic rate, body temperature and heart rate to enable them to survive very long periods of cold weather, surviving only on the food reserves they stored as fat in the fall. Bears, on the other hand, maintain a fairly high body temperature and may wake up during the winter during periods of mild weather.
Hibernation is one type of behaviour animals have evolved to deal with periods of low food availability. Others animals adapt to live in an environment of snow and ice. Snowshoe hares change colour and ruffed grouse grow pectinations, fleshy growths on their feet, in late fall which serve as snowshoes to allow them to walk on the snow. Other animals, such as squirrels, remain active during the winter but store caches of food in the fall to help them make it through the tough months.
Hibernators are the masters of dealing with a harsh environment and groundhogs go through some pretty complicated physiological changes during this process. I think everyone is familiar with groundhogs, also known as woodchucks. They range throughout mainland Nova Scotia and can be found along the edges of fields where they feed on grass and shrubs.
Late in the fall groundhogs go on a major feeding spree which allows them to build up a thick layer of fat. Late in the fall they will seal themselves into their burrow to wait out winter. Over a period of time their body temperature will drop from a high of 37 degrees to a low of 3 degrees during the coldest days of winter. During hibernation their heart rate will also drop from a high of 80 beats a minute when actively feeding in the summer to 5 beats per minute. This low level of activity allows groundhogs to exist on their fat reserves until they emerge in the spring. Even with a healthy fat buildup going into the winter groundhogs may lose up to a third of their body weight over the winter.
While some people are able to escape winter by becoming snowbirds and travelling to warmer climates, even for a week or two, the remainder of us will have to dress a little warmer, and put an extra log on the fire as we wait out the arctic vortex.
Don MacLean is an outdoor writer and biologist who lives in Pictou County.