In the continental United States and Canada, there are at least 30 species of birds that use birdhouses during the winter.
The majority of backyard birds in North America migrate to warmer climates in the colder months, but your backyard birdhouse can become the winter home of bluebirds, cardinals, chickadees, jays, magpies, swallows, sparrows, and wrens.
Putting up a birdhouse for birds to use in the winter gives small birds shelter from the worst winter cold, and gives you opportunities to enjoy birding all year round.
But why do some birds choose not to fly south for the winter?
Why Some Birds Use Birdhouses in the Winter
Many of the birds that use birdhouses during the winter are “cavity nesters.”
They build their nests inside sheltered chambers or cavities in trees, between rocks, and in the cracks and crevices of old masonry and rotting siding.
They don’t build nests in the open on a ledge or on the limb of a tree.
Of course, the same birds that use birdhouses throughout the winter are capable of finding other places to stay.
They might sleep under evergreen trees or shrubs, or in dense, prickly ground cover.
They might nest in the dead leaves at the bottom of a pile of brush. They can find roosting pockets in hay or dead grass, or they can just huddle together on the ground.
Birds that spend the winter in cold places attempt to build up body fat in the fall. (Migrating birds attempt to build up body fat, too, although they use it as their main fuel for the long flights that take them to warmer destinations.)
Body fat gives birds a way to generate body heat in cold weather, and it acts as a kind of insulation against the cold.
Finding a birdhouse to stay out of the wind, however, helps the bird maintain its body fat and extends its survival against starvation when food is hard to find.
Feathers, especially downy feathers, provide birds with protection against the cold. Birds can fluff out their feathers to trap relatively warmer air against their bodies, so they do not chill as rapidly.
They can also cover exposed parts of their bodies, such as their legs, to prevent the loss of body heat.
But feathers do not protect birds against the cold when they have to fly through the cold air.
They also do not prevent the evaporation of body fluids through the bird’s cloaca and nostrils, causing winter dehydration, especially when regular water supplies are frozen over.
Making Birdhouses More Hospitable for Backyard Birds in the Winter
There are several things you can do to make birdhouses in your backyard more comfortable for your winter visitors.
Firstly, clean out old nests.
There are some birds, like pigeons, that don’t mind nesting in other birds’ filth.
However, taking old nesting materials, broken eggshells, and bird droppings out of your birdhouse makes it a more desirable home for the more fastidious birds you want in your yard.
Don’t pick up old bird nests with your hands. Wear gloves. Bird droppings, even when they are dried, can be loaded with bacteria and viruses, especially the bacteria and viruses that cause stomach upset.
Place old nesting materials in the compost heap or in the trash.
Rinse off your gloves before you take them off, and wash your hands and forearms with warm soapy water for at least 15 seconds before you start other activities.
It also helps to patch any holes in the sides of the birdhouse that may have appeared during the summer.
Ventilation is fine in the summer, but drafts reduce the livability of your birdhouse in the winter. Caulk the cracks, and replace any broken wood.
Birds using birdhouses as winter roosting places may not build their usual summer nest, but they appreciate warm, soft materials between them and the floor and sides of the house.
Tear up some old rags or toss in some cotton balls (not Q-tips) for insulation and as nesting material.
Don’t make roosting birds sit on the bottom of the box. Give them a perch that keeps them an inch or two (3 or 4 cm) off the floor of the birdhouse.
Expect multiple birds to gather on the perch to keep each other warm. Putting a perch inside the birdhouse increases the number of birds that can use it.
But remember to remove the perch before the summer nesting season.
Be especially careful to hang your birdhouse where predators like raccoons, opossums, squirrels, and cats can’t reach it.
In the winter, a predator may kill 8 to 10 birds huddled together, instead of just one or two building a nest to raise their young.
Other Ways You Can Keep Birds Healthier and More Comfortable in the Winter
Birds spending the winter in your birdhouse don’t hibernate. They still need food and water. They especially need fatty foods to generate warmth.
Provide seed-eating birds like magpies, chickadees, and jays with black oil sunflower seeds.
Freeze-dried mealworms are a treat for chickadees, bluebirds, cardinals, and robins.
Birds that stay through the winter love heated bird baths.
A heated bird bath on a pedestal, out of reach of cats and other predators, is ideal for winter birds.
You can make your winter bird bath even more attractive to passing birds by paying attention to these features:
- Keep it shallow. Birds want to be able to take a quick drink and maybe to preen their feathers on warm days, but they don’t want to venture into deep water. Just an inch (25 mm) of warm water is enough.
- Don’t use a bird bath with an especially tall pedestal. You don’t want your birdbath so close to the ground that birds are exposed to predators, but the experience for the bird should be similar to getting a drink at a stream.
- Make sure your birds have a good footing. Place some coarse gravel or a few pebbles in the bottom of the birdbath.
- Place the birdbath near bushes or under a tree. This keeps small birds from being spotted by overhead predators, like hawks and owls.
- Keep your birdbath clean. Birds poop where they take their baths. Don’t let bird droppings and debris accumulate in your birdbath.
Frequently Asked Questions About Birdhouses During the Winter
Q. What is a roost box?
A. A roost box is a structure cavity-dwelling birds can use for staying warm in the winter. It is not designed for laying eggs and raising young.
A birdhouse is designed (most of the time) for giving a single breeding pair of birds a place for taking care of their offspring.
A roost box is designed for keeping multiple birds safe from predators, and concentrating their body heat so they can stay warm.
Downy woodpeckers, bluebirds, titmice, nuthatches, chickadees, wrens, swallows, flickers, warblers, swifts, and owls are attracted to roost boxes.
Bluebirds often pile in all together to stay warm. As many as 150 bluebirds may gather at the same location to get in out of the cold.
Sometimes different species of seed- and insect-eating birds use the same roosting box to avoid freezing.
Owls, on the other hand, feed on other birds, and are not particularly appreciated as roommates. Chickadees and downy woodpeckers like to roost alone.
If you mount a roosting box on a pole, add a baffle under the box to keep predators out.
Q. How can I attract birds to a roosting box?
A. Mount the roosting box at least 10 feet (3 meters) off the ground.
Most birds feel more secure in higher locations. Add a layer of rocks or moss to the bottom of the box for extra insulation.
Clean the box at the end of the winter to make it more inviting for the next winter’s birds.
Q. What can I use to reduce the cold air inside my birdhouse in the winter?
A. The most important thing to do to make your birdhouse warm in the winter is to plug the holes you put in it for drainage and ventilation during the summer.
You can seal holes with any material that keeps air out. Foam, hay, rags, weatherstripping, and duct tape (applied from the outside) all work.
Another thing you can do, if your birdhouse has a sliding entry door, is to turn the door upside down.
You want the door open at the top of the birdhouse in the summer to let hot air out.
You want the door open at the bottom of the birdhouse in the winter to trap warm air inside.
Q. Should I move my birdhouse to a different location for the winter?
A. There are two important considerations when you are choosing the right place for your birdhouse in the winter.
One is afternoon sunlight. The more sunlight falls on your birdhouse in the afternoon, the longer it will stay warm at night.
You don’t want to put your birdhouse somewhere where it gets sun all day, however, because then it would be exposed to predators.
The other consideration is hanging your birdhouse somewhere where it is out of the wind. Reducing wind chill goes a long way toward keeping birds warm.
Q. My birdhouses and roosting boxes seem to be full, but there are still birds on my property out in the cold. What can I do to give them shelter?
A. Birds like to get out of the wind in evergreens.
Put down pine or cedar branches out of the wind, as high as you can, to give birds a place to warm up in cold weather.
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