Now that winter is upon us here in Minnesota, most of us on exceptionally cold days and nights will stay indoors in our heated houses or apartments, and can curl up in warm beds. Sadly, most animals do not have this luxury, and have to find other ways to survive the frigid temperatures, like the many year-round resident birds in southern Minnesota. Many people worry about birds dying out in the cold, but thankfully, birds have many adaptations they use to stay warm.
First, many birds can use their feathers in different ways to stay warm. Two types of bird feathers offer increased insulation: the semiplume and down feathers; often birds will grow more feathers during the colder months. Many birds ruffle up and puff out these feathers, which creates more warm air pockets around their fragile bodies, which helps them stay warm. Birds, such as blue jays, also can secrete oil from their uropygial gland, found at the base of their backs by their tail feathers, with which they can coat their feathers for added insulation.
Second, body parts that are more exposed to the elements, like the legs and feet, need to be protected. Most birds have scales on their feet to protect sensitive tissues. Also, some birds are able to constrict their blood vessels in their feet so warm blood will not flow into their feet. They do this so colder blood in their feet will not flow back into their core, which can make them even colder. Birds can also lift up their legs one at a time into their plume to warm up their toes.
Third, birds need to eat a lot in the winter, and they will often gorge themselves during the day to have enough energy to survive cold nights. Birds will fill up on fatty foods to gain extra mass, and will often hide snacks in the cracks in bark or other safe spots to save for later. However, sometimes food is just not abundant during the winter. How do birds survive then? One technique used by some birds, like the Black-Capped Chickadee, is nocturnal hypothermia. This adaptation allows these birds to lower their body temperature, and thus will lower how much energy is used.
Finally, one of the most obvious methods of keeping warm is to huddle up together in packs, and the body heat can be shared around. Year-round resident birds here in Minnesota are well-equipped to survive the tough winters. The next time you see a flock of birds this winter, know that they have a built in down jacket to keep them warm!
–Alec Leonetti ’22, for the Cole Student Naturalists
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