Here is the latest For the Birds column:
Winter poses serious challenges for birds and other wildlife.
The cold is the first thing that comes to mind. How do small birds such as chickadees and goldfinches survive sustained sub-zero temperatures? How do water birds such as gulls, ducks and geese stand on ice all day with bitter winds driving through them?
Birds that remain in New England all year have adapted to the low temperatures. Cold may be a challenge, but it’s one they can handle.
Chickadees and other birds have all sorts of adaptations to survive bitter cold days and nights. They increase their weight and fat percentage, they puff out their feathers to trap warm air close to their bodies, they huddle together for warmth, they drop their body temperature at night, and they eat a lot.
Water birds have an extra layer of down feathers to keep dry and toasty. Also, their legs don’t freeze because of a magical counter-current heat exchange between their veins and arteries. It’s not magic, of course, but it’s a complex system worthy of its own column. Let’s just say their feet don’t have to be as warm as their bodies (otherwise they’d be covered in feathers) and the way their blood flows keeps the legs from freezing.
So the cold, while uncomfortable on the most bitter nights, is usually not lethal to even our smallest birds.
Snow also poses a challenge, especially when there is a lot of it. The birds that stay in New England during the winter get their food from natural sources. Even the birds that visit our feeders daily get the majority of their food “in the wild.”
When snow covers the weed seeds and other food sources on the ground, birds have to be even more resourceful to find a way to get to the seeds or to look elsewhere for food. But they manage. They either rely more heavily on bird feeders or find another source of food, such as berries left over on trees and bushes.
Ice, however, poses a real problem for birds. Parts of southern New England were covered in ice last week as snow turned to freezing rain. Then the temperature plummeted again, covering everything in a sheath of shiny ice. Typically when that happens, the temperature rises again quickly and the ice is melted by the next day. This time, however, it remained cold and ice covered the landscape for four days.
That’s four days of natural food sources being covered by a layer of ice. Every berry or crab apple had its own protective shell. Seeds on the stalks of tall grasses were tantalizingly in view, but off limits because of the clear coating. Many of the mice and voles that sustain our hawks and owls were trapped under the surface because of the impenetrable layer of ice.
So what did the birds do then? Winter is a time when birds need more food than usual, not less. My guess is that birds that visit feeders spent a little extra time in their favorite backyards. Birds that do not visit feeders, such as robins, simply flew to where food was available. Trees and grasses were ice-free not far to the south. A short ways north, snow was the covering instead of ice.
Our winter birds are highly resourceful, smart, and well-adapted to New England winters. I know, it’s hard to not worry about them when the weather gets harsh, but they do just fine out there.