All backyard birders understand the importance of bird houses for providing birds with suitable nesting sites, but after nesting season ends roosting boxes can be even more critical for birds’ survival. But how is this type of shelter different than bird houses, and how can birders add it to their yards?
What Is a Roost Box
A roost box is similar to a bird house 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 at once. Depending on the bird species and size of the flock, a dozen birds or more may take advantage of a single roosting box to share body heat through cold winter nights. This communal roosting in a sheltered spot greatly improves the birds' chances of surviving harsh weather and sudden freezes.
Bird that frequently use roost boxes include:
- Downy woodpeckers
Other species, typically smaller birds or other species that use bird houses, may also take advantage of roosting boxes. These boxes can also be critical emergency shelter for any birds in extreme weather conditions.
Roost Box Designs
At first glance, a roost box looks very similar to a bird house, and in fact many birds will use empty bird houses for roosting even though they aren’t ideal. To encourage birds to roost, a well designed roosting box will have…
- Fewer ventilation and drainage holes to conserve more heat
- An entrance hole near the bottom instead of the top to prevent rising heat loss
- Interior perches to accommodate greater numbers of birds without smothering
- Scored walls or interior mesh to help birds cling and climb safely
- A hinged side, bottom or top for easy cleaning
- A metal guard around the entrance hole to deter predators
- Larger than typical dimensions to accommodate more birds
- Thicker walls for better insulation in winter
It can be easy for birders to convert bird houses into winter roosting boxes by making simple changes to nesting shelters. For example, a bird house may be able to have its front panel flipped to move the entrance hole location, and using sturdy tape to block some of the ventilation and drainage holes can keep the house warmer. Adding wood shavings to the bottom of the house improves insulation for cold weather as well.
Roost Box Placement
Roosting boxes should ideally be placed in a sheltered area protected from prevailing winter 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 and keep unwanted wildlife out of the box.
Where to Buy Roost Boxes
Many wild bird and nature stores offer a selection of roost boxes and convertible bird house designs that can be changed to roost boxes in the winter. Online retailers offering different bird roost box designs include:
Because bird houses and roost boxes are so similar, it is also possible to purchase a bird house and make simple modifications to turn it into a cozy winter shelter for backyard birds.
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.
- Clean the roost box periodically, removing any buildup of feces, shed feathers or other debris. Only clean the box when it is not in use, and be sure it is thoroughly dry and ready for birds to use again at night.
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 roosting 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.