THE WASHINGTON POST – Against a backdrop of fluffy white snow, a brilliant red cardinal perches on a tree branch. It’s a beautiful sight – but did you ever wonder how these feathered friends stay warm and cozy when it’s freezing outside?
Naturalist at Schlitz Audubon Nature Centre in Milwaukee, Wisconsin Jean Strelka has been studying birds for 30 years. Besides cardinals, other birds that don’t migrate during winter include chickadees, owls and some woodpeckers and robins.
Strelka said these birds use different strategies to cope with cold weather.
In the fall, birds grow extra feathers – their version of a winter jacket – to prepare for the colder months. When temperatures drop, birds keep warm by shivering, “Just like you jumping up and down when you get cold outside,” said Strelka.
Some species, such as chickadees and bluebirds, often huddle together to share heat.
Have you ever noticed a bird puffing out its feathers on a chilly day? This is another cold-weather adaptation: By trapping air in its feathers, the bird creates a toasty layer of warmth around itself.
Some birds use a more extreme strategy to survive. In a process called torpor, “Birds are actually able to lower their body temperature by as much as 50 degrees,” Strelka said.
A bird’s normal body temperature is 105 degrees. By bringing body temperature closer to the air temperature, torpor helps birds conserve heat and energy, especially at night.
But it’s risky: Because birds can’t move during torpor, they’re more vulnerable to predators.
Even with these adaptations, birds can still use our help when it’s cold outside. By providing extra shelter in your backyard, you can protect birds from frigid temperatures and predators.
A brush pile built of sticks and evergreen branches offers a cozy place to hide. So does an old Christmas tree, positioned safely away from the wind.
Roost boxes are a special type of birdhouse that you can build or buy. Birds enter these thick-walled boxes through a hole at the bottom and can rest on perches inside. Harsh winters make it challenging for birds to find food. You can ask a grown-up to help you install a feeder, or make your own using pine cones, peanut butter and seeds.
To protect birds from high-speed window collisions, place feeders either within five to 10 feet of your home or more than 20 feet away, said owner of Wild Birds Unlimited in Mequon, Wisconsin Dan Panetti. Try to keep your feeders full if you know a storm is coming.
“Birds can sense it and feed like crazy,” Strelka said.
If you choose a seed blend for your feeder, look for peanuts, sunflower seeds or safflower seeds as the main ingredients.
These provide nutritious calories, said Panetti. Just like us, birds enjoy a variety of food, so you might also offer mixed nuts, mealworms or suet, a form of fat that’s an excellent source of energy in the cold.
Want to create the ultimate haven for wintering birds? Consider installing a heated bird bath. Birds need fresh water to survive – for drinking and to keep their feathers in good shape. Not only do clean feathers keep birds warmer, “birds can fly better with clean feathers,” said Panetti.