January, for Dakota people, brings the “hard moon,” or “withéȟi wí,” and the hardships created by Minnesota’s winter. All creatures take notice and care to survive in the coldest season of the year.
One of the smallest creatures in the winter landscape is the chickadee. This stalwart, tiny bundle of feathers and fluff adapts to survive in harsh Minnesota January. Minnesota is home to two species of chickadees: the boreal chickadee and the black-capped chickadee. The smaller boreal chickadees are winter visitors to bird feeders in southern Minnesota. The larger, black-capped chickadee is an abundant, permanent resident, at home in urban and natural areas throughout the state.
The Minnesota Breeding Bird Atlas, a cooperative project between Audubon Minnesota and the University of Minnesota Natural Resources Research Institute, estimates the black-capped chickadee population in Minnesota is over 1.98 million birds.
Chickadees are well adapted to survive Minnesota’s cold winters.
But how does the chickadee stay alive in cold winter weather? It uses three survival strategies.
First, a down jacket. Feathers are remarkable structures. Chickadees have 30% more down feathers in the winter, according to research that measured spring molting. When chickadees fluff up their belly feathers, the structure of down feathers' fine filaments traps the body heat created by the bird’s variable heart rate. Its heart rate can range from 1,200 beats per minute (BPM) when flying, down to 300 BPM on a cold winter night.
You can see chickadees in action all around the Arboretum, especially at the Tashjian Bee and Pollinator Discovery Center, where birdfeeders and walkway gardens full of dried grasses and forbs provide seed and shelter. The building and evergreen shrubs create a windbreak against the harsh winter winds.
Winter strategies for eastern cottontails include growing an extra fluffy coat, hiding from predators and minimizing movement to conserve energy.
Second, temperature modulation. At night, chickadees and other birds such as nuthatches can go into a controlled hypothermia called torpor and reduce their body temperature by 10 to 15 degrees and slow their heart rate to 300 BPM to conserve energy. The birds tuck their heads under their wings to prevent warmth from escaping through their eyes and bill. Chickadees often perch on one foot while the other is tucked into the fluffy belly feathers to warm up. The legs are primarily made of tendons, scales and very little muscle.
With more sun on leafless trees and moisture from snow, this lichen colony thrives in winter.
Third, increased activity levels. Chickadees are in constant motion as they forage in mixed flocks of five to 10 birds, often with nuthatches, downy woodpeckers and occasionally tufted titmice. They are frequent visitors to backyard bird feeders, which may account for 25% of their daily intake; the other 75% is gleaned during nearby foraging. Chickadees can lose up to 10% of their body weight during cold nights, and seeds provide necessary energy.
Woolly worms use diapause metabolism and cryoprotectants, an internal antifreeze, to survive.
To learn more about feeding winter birds, visit Cornell University’s Project Feeder Watch site.
For more information on bird feathers, check out Feathers: The Evolution of a Natural Miracle, a great winter read by Thor Hanson. Lastly, if you want a great cozy space to view chickadees at the birdfeeder and sip hot chocolate, stop into Rootstock Cafe in the warm Oswald Visitor Center.
The Andersen Horticultural Library, with handcrafted Nakashima furniture, is a warm space on a winter’s day.
While you are at the Visitor Center, stop by the Andersen Horticultural Library to look over the large collection of new seed catalogs and the scores of horticultural specialty journals on display for your enjoyment. A visit to the Arboretum can be your strategy to thrive in the deep midwinter.
Zan Tomko is an artist, horticulturist, Minnesota Master Naturalist Instructor and a co-founder of the iNaturalist Minnesota Lichen Map Project. To learn more about the University of Minnesota Extension’s Master Naturalist program, visit their website.
Cover photo by Holly Einess