Black-capped chickadee [Pierre-Charles Dillon]

Trees in Winter

The Nature of PEI | by Gary Schneider

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I know it is early, but November always gets me thinking of the colder months ahead. Most of us know the importance of trees in winter, especially in our cold, windy province. Properly placed windbreaks around houses save precious dollars in energy bills, and make winter much more bearable. Wind creates higher air pressure on the windward side of a house, which then allows that cold air to seep into buildings through any openings, large or small.

Wildlife isn’t worried about heating bills, but trees and shrubs are equally important to many species of wildlife. In fact, plants can mean the difference between survival and death for many of our winter wildlife residents.

One of the many blessings of a mixed forest is that it offers protection from winter winds. A deciduous stand full of maples and birches is a wonderful place in summer, as the heavy leaf canopy provides coolness and shade. But in the winter, it is a different story, without foliage to stop the winds. This is why species such as eastern hemlock, red spruce, and white pine become so important in an Acadian forest. They offer birds such as ruffed grouse and white-winged crossbills protection from the wind, which is important. The more heat birds have to generate, the more food they have to take in.

Many species also make use of white spruce for protection in the winter. White spruce tends to keep its lower branches, often referred to as “skirts,” which provide excellent protection for snowshoe hare, ruffed grouse, grey partridge, and even fox and coyote.

Another great source of protection for wildlife in the winter are dead or dying trees with holes, or “cavities.”  Chickadees, woodpeckers, nuthatches, and other birds use cavities to stay warm, which only makes sense. Black-capped chickadees are favourite birds of mine. They don’t get enough credit for being beautiful, probably because they are quite common, and we tend to look for beauty in the unusual. One of the ways that these tiny birds (they only weigh 15-18 grams!) survive the winter is that they eat large amounts of food daily and then shiver at night, keeping their body temperature high.

It sounds almost impossible—they eat 35% of their body weight each day, and burn it off at night to stay warm. It is why suet, peanuts, and sunflowers are such important components of winter bird feeding. The fat provides energy and calories that are especially critical in the colder months.

On a cold night, the temperature inside a cavity is significantly higher than the outside air temperature.  In addition, less body heat is lost due to cold winds. It is estimated that that a bird roosting in a cavity can spend five to seven hours less time feeding each day, as they do not have to replace nearly as many lost calories.

Northern flying squirrels also use cavities, huddling together in groups of from 4–10 individuals to maintain body heat.

Last but not least, dense shrubs— especially our native hawthorn—can provide some great protection from predators. Without leaf cover, smaller birds can easily be seen by hawks and other species that would love to eat them. Native hawthorns have long thorns that make it difficult for predators to get into the middle of the plant, where small birds are often resting. And even without leaves, dense shrubs such as dogwoods, roses, and spirea at least offer some protection from the elements.

These are just some of the reasons that forests are critical to the survival of many species of wildlife.

Gary SchneiderThe Nature of PEI
Gary Schneider

Gary began writing for The Buzz in the May 2018 issue. He co-chairs ECO-PEI and started the Macphail Woods Ecological Forestry Project in 1991. The project demonstrates ecologically-sound forest management, with a focus on environmental education, conservation of rare plants, and the restoration of PEI’s native forest. He is an avid birder and lives in Tea Hill.