By GENE BULLOCK
When the weather outside is frightful, and the fire inside delightful, do you wonder how your backyard birds are managing?
You hope they are all snuggled down in their cozy beds while visions of suet dance in their heads. But unless they’re tucked away for the winter like celebrity groundhog Punxsutawney Phil, they have to venture out in the cold to find food. They need to replace the calories they burn to stay warm and well nourished.
Like us, birds are warm-blooded, and need to maintain stable body temperatures to survive. For birds, that’s about 106 degrees Fahrenheit.
Some birds, such as hummingbirds, can temporarily slow their metabolism and reach a state of torpor for short periods. This helps conserve core temperatures. People have reported seeing a hummingbird perched on their feeder that seems frozen and lifeless. I tell them these birds are probably just fine and will recover as soon temperatures warm up.
I remind them, however, that hummingbirds learn to depend on feeders, especially during cold winter months when they have fewer options. And subfreezing days are no time to leave them in a lurch with frozen nectar. When temperatures plummet below freezing, keep an eye on feeders, keep them full, and swap them out when they get slushy and start to freeze. We bring ours in after dark and put them back up around daybreak. We also keep watch during the day.
Birds have other strategies for staying warm. Chickadees, for example, can make themselves shiver to raise body temperatures. Marine birds, geese and other birds add an insulating layer of fat. Some birds, like the common eider, grow an extra layer of down that is prized for its insulating qualities. Chickadees and sparrows can fluff out their feathers and form into a ball with their bills and feet tucked in. Shorebirds are sometimes seen standing on one leg with the other leg tucked in. This saves body heat by reducing the amount of exposed area.
Of course, birds also huddle together in communal roosts to stay warm. I once watched a flock of groove-billed Ani’s form themselves into a big ball of feathers that hung from a branch. I’ve seen noisy flocks of parrots tuck themselves into dense foliage and virtually disappear. In Monroe, bird watchers gather to witness the nightly return of roosting Vaux’s swifts to a lone chimney structure.
Why do some birds stay all winter while others leave for the tropics? Mortality can be high during migration. They face a variety of hazards, including predators, hunters, long stretches of open water, and storms than can keep them pinned down and unable to feed themselves. I’ve watched storm-bound birds starve in the Dry Tortugas Islands off the coast of Florida and could do nothing to save them.
Birds that stick around also have a competitive advantage in maintaining a year-round territory. Their success for countless generations is proof that these survival strategies work. Let’s hope that man-made changes in habitat and environment don’t undo what it took evolution eons to accomplish.
In the meantime, there is much you can do to give your backyard birds a helping hand. Suet cakes are a high-energy food source for woodpeckers, nuthatches and other birds. Black oil sunflower seeds are also a rich source of nutrition for a variety of birds, including chickadees, finches, pine siskins and many others.
You can help birds survive the winter with well-stocked feeders. In return, they will reward you with an unending display of exuberant activity and vibrant color.