How do they do it? How do wild birds survive in the dead cold of winter? We all know as humans that when the thermometer hits -20 C or colder we hurry from the car to the house. Even as we are adorned in thick, down-filled coats with toques and mitts, it is still bitter and unbearable. When the wind chill kicks in, it can even be life-threatening to humans yet wild birds carry on each day seemingly unbothered by the brutality of winter. What do they have that we don’t?
Birds have the highest body temperature in the animal world, ranging from 105 to 112 degrees F compared to about 98 degrees for humans. Keeping these temperatures up requires a lot of calories in winter.
Preparation for the cold season begins in the fall when wild birds begin to build up fat reserves. At this time of year, food sources are plentiful as many plants have gone to seed, and birds will eat excessive amounts. An extra layer of fat serves as insulation and can provide extra energy needed to maintain their body temperature.
Feathers are obviously the staple in being able to stay warm. In fact, wild birds will grow about one thousand new feathers for winter! These are mostly down feathers which lie close to the skin.
You may witness birds shivering and puffed out in winter but they are not doing this because they are cold. It is actually a way to produce more body heat. This method is only used in the coldest of weather as it requires a lot of energy and calories. The exterior feathers provide a source of water and wind-proofing as well as insulation.
You may sometimes see a bird rubbing its head from the tail upwards. All birds have an oil gland located at the base of their tails, and this movement spreads oil throughout their feathers. Properly preened feathers are a requirement for wild birds, especially in winter.
I have been asked many times why the birds’ skinny little legs don’t freeze off. The answer is that birds’ legs are designed with very hard scales that reduce heat loss. Birds can as well control the temperature of their legs separately from the rest of their body by restricting blood flow.
Sometimes birds will tuck their head under a wing and crouch down to keep their face and legs warm. On sunny winter days, birds take full advantage of the sun’s warm touch. They will find a perch in direct sunlight and conserve calories as they warm their bodies.
The most surprising thing about wild birds in winter is the way they make it through the long, severely cold nights. Some birds, like chickadees and nuthatches, will roost together in small groups inside a cavity – such as a natural tree cavity or a human-provided source like a birdhouse or winter roost, where they will share their body heat. I once saw a picture of about 16 chickadees packed inside a roost like a little puzzle.
Another skill birds employ during the night is to go into a state of torpor. This is a state of reduced metabolism where they bring down their body heat by about 50 degrees. It is a major way to reduce and conserve calories but it can be dangerous. In this state, a bird’s reaction time will be very slow. They will be vulnerable to predators until they bring their metabolism back up.
To help wild birds have a bit of an edge on winter, here are some tips.
- Provide black oil sunflower as a staple food. This seed is very high in fat and consumed by all birds in winter. You can also consider shelled sunflower which is consumed even more easily.
- A quality suet is an excellent source of fat, energy and calories and woodpeckers and nuthatches in particular are attracted to it. Water availability is very important to birds for preening purposes. Water is used to wet the oil gland, making it easier to disperse the oil throughout their body. It also assists in digestion in the cold.
Heated birdbaths are a great way to offer water, and don’t worry – you will not see birds bathing, as you would in summer.
- If you leave birdhouses out, they will provide a shelter for birds to roost in during the night.
Wild birds are not dependent on feeding stations, as they are always able to find natural foods but you will certainly make life much easier for them if you offer high quality foods and keep your feeders full. In return, you will be treated to the antics and beauty of wild birds all season long, keeping your spirits as bright and cheerful as the birds themselves.
Sherrie Versluis owns The Preferred Perch on St. Mary’s Road. Phone: 204-257-3724.