by Geoffrey Carpentier
‘Wish I had a fur coat – oh wait – I do’ says the fox! Well, mammals are furry to be sure, so let’s continue our exploration of how mammals deal with Canadian winters. To refresh your memory, we’ve discussed hibernation and all the similar strategies, some mammals and a few reptiles and amphibians employ, to survive the coldest parts of winter. So what other options do they have?
Well, if you are going to stay awake all winter, you have to have a means to stay warm, find food, and avoid predators, all while dealing with deep snow. Keeping warm is, of course, very critical. The pelage (i.e. fur) of animals is generally layered with coarse, air-trapping, protective, outer fur which covers the finer inner hair. In some mammals, such as deer, the outer guard hairs, themselves, are hollow and thicker, so their insulative properties are enhanced even more. The polar bear is, also, a good example of a mammal utilizing the inherent properties of specialized hairs and the hollow hair strategy to keep warm.
The summer pelage of some animals is very different than its winter coat. For example, the White-tailed Deer does not have the inner fur layer, in the summer, and only has the coarse outer layer to keep the animal cooler and to hold biting insects at bay. In the autumn, this second layer of fur is quickly added, when it gets cold. The thicker winter hairs create a greater surface within which to trap air. All of this leads to better insulation and subsequently warmth and protection for the host animal.
Mammals eat a lot in the winter and, as such, put on layers of fat to ensure they have enough energy to create sufficient body heat to protect themselves. The blubber of some sea mammals, such as whales and seals, is well documented in this regard, to the point where, in days past, they were hunted for the oil derived from their fat layers. The oil was used for cooking, heating homes and lighting lamps since it was of such high quality.
The name, of the 1967 rock band, 'Three Dog Night' references a practice Aboriginal peoples utilized, in Australia, Russia, Canada, Scandinavia and Alaska, to deal with extreme temperatures. When possible, they would huddle with one or more dogs, on the coldest nights, to share body heat. The phrase, itself, originated in the Australian Outback. It was first mentioned in an 1894 article, in the Sydney Morning Herald, where it was described as a night so cold, "three dogs and a blanket would not keep a man warm." Of course, dogs are perfectly able to snuggle without us, but this simply tells us, cuddling to share our own internal heat is an effective way to fight off the cold. There is a word to describe this mechanism to share body heat, it's called thigmotaxis, the art of snuggling. Elephant Seals in Antarctica employ this strategy effectively.
One other means to ensure survival is to find a warm place to shelter. To our chagrin, this might become our homes, in the case of some mice and squirrels, or it might be an underground den, bird house or hollow tree. This also may be a place where one or more animals share the same space. All this means, the animals will have enough energy reserves left to generate sufficient body heat when they need it most. Squirrels usually build dreys, a leafy nest in hardwood trees. It looks messy and ill-formed, but in reality it is quite toasty warm inside. It may lie dormant for days at a time, but as soon as it gets too cold the squirrels enter it and sleep through the coldest part of the weather.
The coping mechanisms of animals is fascinating and varied, but, clearly, many different strategies are employed to ensure survival. Alright, that’s enough for today. Let’s pause and reflect until next time, when I finish this story about how mammals thrive and survive in winter.
Geoff Carpentier is a published author, expedition guide and environmental consultant. Visit Geoff on-line on LinkedIn, Facebook and Instagram
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