Our local meteorologist reported, “Days of cold, strong east winds will take hold Monday afternoon and last through the day Wednesday.”
Each year, as the weather turns frigid, I wonder, “How will the birds find warmth?”
The answer to this question is actually quite fascinating. Some species cope by migrating away to warmer climates; but those who stick around through the winter have many physical and behavioral adaptations to maintain body warmth. I cut the following information from About Birding. How many of these facts do you already know? Which ones are new? Which surprised you? I was surprised to learn about the scales on bird legs and feet… now I know their function!
Feathers: Birds’ feathers provide remarkable insulation against the cold, and many bird species grow extra feathers as part of a late fall molt to give them thicker protection in the winter. The oil that coats birds’ feathers also provides insulation as well as waterproofing.
Legs and Feet: Birds’ legs and feet are covered with specialized scales that minimize heat loss. Birds can also control the temperature of their legs and feet separately from their bodies by constricting blood flow to their extremities, thereby reducing heat loss even further.
Fat Reserves: Even small birds can build up fat reserves to serve as insulation and extra energy for generating body heat. Many birds will gorge during the fall when food sources are abundant, giving them an extra fatty layer before winter arrives.
Torpor: Many birds will enter torpor to conserve energy during cold winter nights. Torpor is a state of reduced metabolism when the body temperature is lowered, therefore requiring fewer calories to maintain the proper heat. Most birds can lower their body temperature by a few degrees, but torpid birds have lowered their body temperatures by as much as 50 degrees. Torpor can be a dangerous behavior, however, as the reduced temperature also leads to reduced reactions and greater vulnerability to predators. Hummingbirds, chickadees, swifts and other types of birds regularly use torpor as a way to survive cold temperatures.
Fluffing: Birds will fluff out their feathers to create air pockets for additional insulation in cold temperatures.
Tucking: It is not unusual to see a bird standing on one leg or crouched to cover both legs with its feathers to shield them from the cold. Birds can also tuck their bills into their shoulder feathers for protection.
Sunning: On sunny winter days, many birds will take advantage of solar heat by turning their backs to the sun (therefore exposing the largest surface of their bodies to the heat) and raising their feathers slightly. This allows the sun to heat the skin and feathers more efficiently. Wings may also be drooped or spread while sunning, and the tail may be spread as well.
Shivering: Birds will shiver to raise their metabolic rate and generate more body heat as a short term solution to extreme cold. While shivering does require more calories, it is an effective way to stay warm.
Roosting: Many small birds, including bluebirds, chickadees and titmice, will gather in large flocks at night and crowd together in a small, tight space to share body heat. They can roost in shrubbery or trees, and empty birdhouses and bird roost boxes are also popular locations to conserve heat. Even individual birds choose roost spots that may have residual heat from the day’s sunlight, such as close to the trunk of a tree or near any dark surface.
How many of the adaptations is the Mourning Dove using to find warmth?
Use this photo of a Mourning Dove perched in the warmth of Spring as a frame for reference.
Science behind this post:
How do Wild Birds Keep Warm in Winter? – http://birding.about.com/od/birdingbasics/a/howbirdskeepwarm.htm
Winter Bird House Plans- Keep Your Birds Cozy all Winter Long – http://www.birdwatching-bliss.com/winter-bird-house-plans.html
Roost Box for Songbirds – http://wdfw.wa.gov/living/projects/roost.html
Suet Feeders for Birds – http://wdfw.wa.gov/living/projects/suet_feeders.html