Gateway Gazette

How Do Birds Stay Warm During a Cold Freeze

Glenbow Ranch Provincial Park

Now that we have survived January and the extreme cold spell that came along with it, have you ever wondered how certain birds survive extreme cold? Do they not get cold? How do they keep warm during cold winters? Well birds have numerous incredible adaptations that allow them to survive even the most frigid conditions. 

First off, birds are warm-blooded animals that have much higher metabolism, and thus higher body temperature, than humans. While the exact measurement varies for different bird species, the average bird’s body temperature is 105 °F (40°C). So what do birds do to keep warm?

Physical Adaptations

  • Feathers: Birds’ feathers provide remarkable insulation against cold (hence why so many jackets are made with feathers!) and many species grow extra feathers for more protection. The oil that coats birds’ feathers also provide insulation as well as waterproofing.
  • Legs & 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 without risking frostbite.
  • Fat Reserves: Even small birds can build up fat reserves to serve as insulation and extra energy for generating body heat. 

Behavioral Adaptations

  • Fluffing: Birds fluff out their feathers to create air pockets for additional insulation, this can make them look fat and puffy while they are toasty warm. 
  • Tucking: It is not unusual to see a bird standing on one leg or crouched to cover their legs with its feathers to shield bare skin from the cold. Birds can also tuck their bill into their shoulder feathers for protection and to breath in warmer air.
  • Sunning: On sunny winter days, birds will take advantage of solar heat by turning their backs to the sun (exposing the largest surface area) and slightly raise their feathers. This allows the sun to heat their skin and feathers more efficiently.
  • Shivering: Birds shiver in order to raise their metabolic rate and generate more heat as a short term solution to extreme cold. 
  • Roosting: Many small birds will gather in large flocks at night and crowd together in a small tight space to share body heat. Even individual birds will choose roost spots that may have residual heat from from the day’s sunlight, such as close to the truck of a tree or near a dark surface. 

Lastly, 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. Torpid birds have been able to lower their body temperatures by as much as 50 degrees. Torpor, however, can be dangerous as it leads to slower reactions and greater vulnerability to predators. 

Although, birds are highly adaptive in cold weather in order to conserve heat and stay warm, many still succumb to frigid temperatures and bird mortality can be very high during severe winters. There are a few things we can do to help them during cold days. First, offer good food such as seed, nuts, scraps, peanut butter and other items high in fat and calories. Second, keep feeders full! Thirdly, offer liquid water if possible (heated bird baths). Finally, by providing suitable shelter such as evergreen shrubs, brush pile and coniferous trees.

Source:

Mayntz, M. (2019, October 16). How do wild birds keep warm in winter? Retrieved from https://www.thespruce.com/how-do-wild-birds-keep-warm-in-winter-386721

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