With the arrival of colder weather, it’s time to start thinking of how to help those birds which overwinter here. Many of us put out food for them (sunflower seeds for chickadees and nuthatches, peanuts for blue jays, and niger seed for various finches), but shelter is another consideration. Freezing rain or deep snow, bitter temperatures and biting winds can all prove fatal to even the hardiest of birds. Fortunately, there are some ways in which we can help our feathered friends to survive.
Deciduous trees provide shelter in summer, but once their leaves are gone, so is most of their benefit. Growing evergreens in your yard is one natural way to provide shelter for birds. Lacking these, some people opt to build brush pile shelters, including evergreen boughs. These should include small branches and air spaces for roosting and insulation, and are best in a fence corner, sheltered from winds. Another natural way we can help is to leave any pruning until spring, thus leaving more cover for birds.
This winter my husband and I are using a new type of bird shelter (an action prompted because of the recent removal of some of our trees). We are trying out some roosting boxes. These can be bought at wild bird supply stores, but can also be made more cheaply from scratch, which my husband has done. A dozen birds could use a single box, thus sharing body heat on cold winter nights. Chickadees, nuthatches and downy woodpeckers might use these boxes (and, of course, house sparrows).
At first glance, you might think a roost box looks like a birdhouse, but there are several differences. Most noticeable is that the hole is near the bottom, which will prevent rising heat loss. A metal or hardwood guard around the hole will help to deter predators. The hole can vary in size, depending on bird species, about 1.5 inches (3.8 cm) for most small birds. We are using a couple of sizes, including one with a larger hole. (For the last several winters we have had a mourning dove stay all winter, so this is intended for it, if it stays again.)
The boxes are also larger than birdhouses, with no ventilation holes, so as to help keep body heat inside. The walls are usually thicker, three-quarters to one inch (2.0 to 2.5 cm), to provide better insulation, and there are interior perches so more birds can use it. The inside walls without perches are scored, or have an interior mesh, to help the birds cling to it. Tape or caulk added to the seams will help prevent drafts. A roof or wall with hinges or screws will make it easy to clean out the box a couple of times a year.
Roosting boxes should be mounted much higher than a birdhouse, between six and 15 feet (approximately two to five metres) from the ground, on a pole or tree trunk. If using a pole, you could add baffles against predators.
Bird shelters should be painted dark colours on the outside to absorb the most heat, and should be positioned to face towards the sun. If possible, they should be in a sheltered area and should not have outside perches. Insulating material such as wood chips or dried grass should be added on the floor.
Another type of shelter you could purchase is a roost pocket. This is a basket-style shelter made from woven thatch material, which provides good insulation for birds.
Backyard birders should also leave up birdhouses over winter. These won’t be as effective as specialized boxes, but will at least provide some shelter from winds, snow or rain. These would be most useful if you plug the air vents and flip the birdhouse over so the hole is at the bottom. Or make a separate front for winter and just switch that wall. Put in some insulating material in a birdhouse, too.
Roost boxes will be most popular with birds in winter but can be left up all year for shelter during any inclement weather. For further information on how to construct a roosting box, check out these websites: