A cold winter’s day will find me huddled inside, hot cocoa in hand, watching through the window as snowy winds blow fiercely through the woods. And winter can get pretty fierce here in Michigan's Upper Peninsula. The thermometer’s thirty below would ease my guilt at not being outside if it wasn’t for the little chickadees, bold blue jays, and cheerful pine grosbeaks, among many others, visiting our feeders. If they can brave the weather, why can’t I? After all, I have a comparatively luxurious home-nest to return to after a chilly foray outside.
I have no idea what gives these birds the psychological ability to endure, other than the sheer demands of necessity. Chickadees and pine grosbeaks even thrive in Alaska. Just how do they do it?
There’s not a lot of fat on chickadee bones to help insulate the birds from winter temperatures, at least not in the mornings after a night spent in a form of regulated hypothermia during which the chickadees' body temperatures drop by 12 or 15 degrees. However, after a day of eating frozen insects and seeds, chickadees are “bulging with fat” according to wildlife ecologist Margaret Clark Brittingham.
Like jays, chickadees stash seeds in autumn to eat in winter. According to the Montana Naturalist, one chickadee can store up to 80,000 seeds in a season, roughly 1000 seeds a day. This is one reason why chickadees are so intelligent – in order to survive, they need to make a detailed mental map of where exactly they cached those 80,000 seeds.
Finding supplemental food at human-supplied feeders can help chickadees survive in greater numbers during harsh weather. In studies, the survival rate nearly doubles for those who use feeders in particularly extreme winters. Without those feeders during such winters, the chickadee communities experience greater loss.
In milder winters, however, those chickadees who are solely wild, providing their own food as they always have, survive at roughly the same rate as those chickadees who do use human-supplied feeders. And even those chickadees who do come to our feeders don't come to depend on human-supplied seed...during mild winters.
This latter is good news for chickadee communities. It's also good news for those of us who worry we may be undermining their traditional living skills by feeding them. Evidently, even when supplied with seed, chickadees who eat at our feeders also continue to maintain their traditional food knowledge and skills despite having access to easy food.
But seeds and frozen insects aren’t enough for a chickadee to survive a winter. They also need small tree cavities, some as small as a quarter, to snuggle into overnight. A study in Alaska found birch trees appeared to be the preferred nighttime roost for chickadees in that region.
For the first time in a lifetime of living in the Northwoods, we have flocks of pine grosbeaks at our feeders this year. According to the Peterson Field Guide to Birds, the Upper Peninsula is located at the southernmost point of their winter range. They love the seeds of crab-apples and mountain-ash. Our woods/yard (aka forest garden) is full of these.
According to the Minnesota DNR, low seed crops in Canada often lead to a greater number of pine grosbeaks migrating south to the Northwoods for the winter which makes me wonder if this year’s unprecedented number of pine grosbeaks in the area here is a direct result of the record-breaking wildfires in Ontario this last year. Nearly 2 million acres (793,000 hectares) of land, that is habitat, were destroyed by wildfires in 2021 in Ontario – this is the single greatest area of land ever destroyed by wildfire in the province in known history.
Sadly, even before this year’s devastating wildfires, pine grosbeaks were thought to be in decline, according to the North American Breeding Bird Survey.
Cold also impacts trees. According to the lunar-based calendar of the Cree, this part of winter (roughly January in the Western calendar) is the time of Opawahcikanasis, the Frost Exploding Moon, when "[t]rees crackle from cold temperatures and extreme cold starts."
More than 50% of a tree is made up of water. Fortunately, the sugars in a tree’s sap act as an anti-freeze…at least to a certain point. On really cold days, especially if a tree is in the sun or has thin bark, when the sun goes under a cloud or when it sets in the evening, the sharp drop in temperature causes water in the cells of the outer layers of the tree to freeze more quickly than water in the inner wood. The wood on the exterior shrinks, but the inner wood remains unaffected. This sharp difference cracks the wood in a loud bang. The Frost Exploding Moon. The resulting crack in the tree may heal with time, but it does also leave the tree vulnerable to the penetration of pests and fungi while the tree’s fracture is healing.
When temperatures really plummet, there is a silver lining to those icy clouds, at least for us and the forests we call home. Extreme cold, especially when it is prolonged, is an important part of what can help protect the Northwoods from invasive insects. A number of invasive insects are negatively impacted by very cold temperatures. Emerald Ash-Borers, some woodticks, the wooly adelgid threatening hemlock trees, all of these begin to die off in greater numbers when the temps fall below zero.
Species differ in terms of how cold it must get before they are significantly impacted, but usually by 20 or 30 below, most invasives are not able to survive in large numbers. However, while many native species can withstand our cold well, some of them will also be impacted by extreme freezes.
Winter is a beautiful time, but it is also a harsh one. As I cozy inside my rather fragile cocoon warmed by fossil fuels and sustained by chocolate imports, the lifeways of our bird relatives just beyond my doorstep are inspirational. Their ability to withstand the harshest of weather carries lessons for us all: the only way to face extreme unpredictable conditions is with fortitude and endurance, flexibility and adaptability. And not a small degree of indomitable spirit, spritely cheerfulness, and sweet-natured song.
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