Winter Bird Survival
The dark days of winter are upon us in the Northern Hemisphere. By the time Winter Solstice marks the shortest day of the year, most birds have migrated to their winter locations, following their food sources. In northern latitudes, year-round residents continue to forage, even on the coldest winter days. Do you ever ask yourself, how do they survive?
Birds have evolved over thousands of years to survive seasonal changes. Keeping warm is a high priority. Access to quality, sheltered roosting sites, such as in large conifers, means birds have places to hunker down for long storms. In the winter, birds often roost early, before the sun sets, anticipating that temperatures will drop quickly. They frequently will puff out their plumage while roosting, creating heat pockets in their down-covered bodies. Titmice, chickadees, and bluebirds seek shelter in the holes of trees--sometimes old woodpecker nesting cavities. Goldfinches and redpolls grow extra feathers in the winter, increasing their insulation. And all birds who experience colder than normal temperatures can shiver. Black-capped Chickadees normally maintain a temperature of 107.6°F, but if temperatures drop below 32°F, they are adapted to shift their body temperature to around 86°F and shiver through the night to survive. Many birds, including chickadees and hummingbirds, can enter a state of torpor in which their respiration and other body processes are slowed, conserving energy until they can forage for their next meal.
Keeping warm takes a lot of energy (a chickadee can lose up to 25 percent of its body weight in a single cold night) and finding enough food in northern latitudes during winter is tricky business. Survival is often dictated by the availability of native habitat. Native flowers such as cockscomb, aster, purple coneflower, sunflower, daisy, goldenrod, tall marigold, and zinnia, develop seed-rich flower heads with supportive stalks that can withstand early snow storms. For larger-billed birds such as woodpeckers, jays, juncos, and sparrows--native pine, spruce, and fir provide power-packed seeds buried beneath the cone scales.
Birds are survivors. In the presence of native habitat, they have numerous adaptations to maximize their survival. So the number one thing you can do to protect birds in the winter? Preserve or plant native habitat and work to encourage your community to follow suit.
Reference: Roth, Sally. (2009) Backyard Bird Secrets for Every Season. Rodale Publishing