All backyard birders understand the importance of birdhouses for providing birds with suitable nesting sites, but after nesting season ends roost boxes can be even more critical for birds’ survival.
What Is a Roost Box
A roost box is similar to a birdhouse in that it provides shelter for birds, but it is not intended for building nests or raising hatchlings. Instead, a roost box provides secure shelter from predators, low temperatures and poor weather for multiple cavity-nesting birds. Depending on the bird species and size of the flock, a dozen birds or more may take advantage of a single roost box to share body heat through cold winter nights, greatly improving their chances of surviving harsh weather and sudden freezes.
Bird that frequently use roost boxes include:
- Downy woodpeckers
Roost Box Designs
At first glance, a roost box looks very similar to a birdhouse, and in fact many birds will use empty birdhouses for roosting even though they aren’t ideal. To encourage birds to roost, a well designed roost box will have…
- Fewer ventilation holes to conserve heat
- An entrance hole near the bottom to prevent rising heat loss
- Interior perches to accommodate greater numbers of birds
- Scored walls or interior mesh to help birds cling and climb
- A hinged side, bottom or top for easy cleaning
- A metal guard around the entrance hole to deter predators
- Large dimensions to accommodate more birds
- Thicker walls for better insulation
Roost Box Placement
Roost boxes should ideally be placed in a sheltered area protected from prevailing winds. If the house gets some sunlight during the day, particularly in the late afternoon, it will retain that heat for a time and be more attractive to birds. Facing the entrance hole south will also help the box get more heat. The ideal height for a roost box varies for different bird species, but the box should be mounted on a pole or tree trunk between 6-15 feet from the ground. If mounting the box on a pole, use baffles to deter predators.
Where to Buy Roost Boxes
Many wild bird and nature stores offer a selection of roost boxes and convertible birdhouse designs that can be changed to roost boxes in the winter. Online retailers offering different bird roost box designs include:
More Roost Box Tips
To make your roost box as attractive and safe as possible for the birds…
- Add a second entrance hole to large roost boxes to help birds exit quickly when they are ready to feed or if they feel threatened.
- Add a layer of moss or small wood chips to the bottom of the box for better insulation and to make it more comfortable. This will also make cleaning easier.
- Paint the box with non-toxic paint in a dark color to help it retain more solar heat. The interior of the box should not be painted.
- Choose a roost box with an entrance hole appropriately sized for your backyard birds. A hole with a 1.5-2 inch diameter is perfect for most small birds, while larger holes could encourage starlings to roost, forcing smaller birds to go without shelter.
- Add tape or caulk to the seams of the box to eliminate cracks that will lead to drafts and heat loss. Birds can lower their body temperatures 10-15 degrees to conserve energy during winter nights, and even a small draft can become fatal during a cold snap.
A safe, warm bird roost box provides excellent shelter for flocks of small cavity-nesting birds to use nightly at any time of year. While roost boxes are more popular during colder months, if you have a well designed roost box up all year long, you’ll see your backyard flocks take advantage of it in every season.