Extreme cold is one of the toughest conditions for birds to handle. With a small body mass and high body temperature, they have to rely on their feathers for insulation. A layer of feathers less than an inch thick is all they have to separate their 103°F body from outside air as cold as 30°F below or even lower.
Food is critical to replenish fat supplies and fuel their bodies, so you might think that birds would spend a lot of time foraging in the cold. But even more critical is simply staying warm. In the coldest weather, most birds reduce their activity, waking up later and going to sleep earlier, and spend a lot of time just huddled in a sheltered spot. The less they move, the better.
Think of birds’ feathers as a big down sleeping bag. Activity requires using their feet and wings, and exposing those to the cold. When they are sitting still, they can pull their feet inside the sleeping bag, fold their wings close to the body and wrap those up as well. Most small birds are also capable of entering torpor, a sort of semi-hibernation in which their body temperature drops to below 60°F and metabolism, breathing, and heart rate slow dramatically. In this way, they use a lot less fuel.
In terms of finding birds in extremely cold weather, look for the food. The only thing that brings birds out of their shelter is the need for food, and they won’t spend any more time than necessary. Bird feeders, obviously, provide a great source of food and always attract birds in cold weather.
Birds are also looking for the most sheltered and warmest place they can find to pass the time. South-facing hillsides or brushy edges are always good places to look, especially when those spots are also sheltered from the wind.
Noticing these things will reveal patterns, and you will quickly develop a sense of where to look for birds in cold weather. A lot of it comes down to the same things that we like on a cold day. A sunny corner with some weedy or brushy habitat to provide shelter from the wind is a nice place to sit. It’s also likely to be a great location for birds.
This article was first published in the January/February 2019 issue of BirdWatching magazine. Subscribe now.