by Geoffrey Carpentier
Last time we explored how some small birds (i.e. chickadees) dealt with extreme temperatures. Now, I’d like to check out other species, to see how they cope. Any bird or mammal must have food, warmth and shelter to survive our winters. We’ve already seen how the chickadees deal with two of those three requirements. The third; food, is managed by constantly searching for insect prey or seeds and berries. Larger birds have the same needs.
The Ruffed Grouse is an important part of our local ecosystem, as they provide food for many predators. They, themselves, have to eat as well, so their winter diet is focused on the buds of trees. Grouse can feed rapidly and do most of their eating at dawn and dusk. Risking predator encounters, they fly to the top of deciduous trees and feast on the ample buds the trees provide. In as little as 30-45 minutes a day, they can find enough food to sustain them, until the following day. At night they usually huddle deep inside tree cover, or, if conditions are ideal, under the snow. They rapidly and deliberately burrow into the snow, to find both shelter and warmth, in the insulated enclosure. Certain predators are wise to this, and foxes, wolves or even a Great Horned Owls can detect their presence, and plunge into the snow after them! Ptarmigan also employ exactly the same survival mechanisms, when they entomb themselves in snowbanks for many hours at a time, sometimes as long as 16 hour a day, according to some sources.
Now, this brings up an interesting question. If the grouse and ptarmigan can simply increase their chances of survival by burrowing into snow, why don’t other birds, like blue jays or cardinals, do the same? Well, the answer is not clear but even if we don’t know why, the reason why they shouldn’t is clear. Snow cover can quickly become a dangerous deathtrap. If a mild daytime thaw occurs and the upper surface of the snow starts to melt and then refreezes, the ice cover would be too thick for small birds to break free, and they would simply suffocate or starve to death. Bigger birds, like the grouse, can easily break through reasonable thicknesses of frozen snow.
Woodpeckers have adopted a different approach, as they can feed all day long, if necessary, and dine on tasty and nutritious insect larvae as they search. At night, they go to roost holes made specifically for this purpose. Nesting holes are generally excavated in living trees, comprised of solid wood, while the winter roost holes are usually drilled, in much less dense, partially rotten, snags, an energy saving practice. These holes may be used for days or even weeks. I remember a few years ago, a rare American Three-toed Woodpecker took up winter residence in a local park.
As an elusive species, few people were able to spot this lodger during the day as it foraged throughout the park. However, at night, just before dusk, it would return to the roost tree. It approached the hole rapidly and virtually flew into it without stopping or lingering on the outside of the tree. This was clearly a mechanism to avoid being detected by a predator.
Some small birds, such as kinglets, which are not cavity nesters, will huddle together, deep inside the foliage of conifer trees, to share their body heat. We saw this same behaviour in the movie “March of the Penguins,” where these birds huddled together, slowly shuffling along and sharing each other’s heat.
Starlings have been shown to use artificial heat sources for survival. In that case, studies showed, these birds found, by huddling up against a chimney, they could garner a great deal of ambient heat. This reduced their own requirements to fuel their body temperature by eating large quantities of food.
There is a great deal we don’t know about how animals cope but we know they do! I’m going to continue with this story, next time, as we look at mammals, to see what they do when it gets a bit chilly. Stay tuned!
Geoff Carpentier is a published author, expedition guide and environmental consultant. Visit Geoff on-line on LinkedIn, Facebook and Instagram.
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