Birdhouses provide safe nesting sites for many species of birds that nest in cavities. Cavity-nesting birds cannot excavate their own nesting cavities in trees or other natural sites, so providing an artificial cavity in the form of a birdhouse gives them a place to raise their young. There are dozens of bird species that will readily use birdhouses, including chickadees, nuthatches, bluebirds, swallows, flycatchers, and wrens. Choosing the right type of birdhouse, placing it in a suitable location, and properly maintaining the birdhouse will increase the chances of attracting nesting birds.
What are cavity-nesting birds?
Cavity-nesting birds are species that build their nests and raise their young inside cavities in trees, snags, or other natural sites. These cavities provide shelter, insulation, and protection from predators and weather. Cavity-nesters include species in the families Paridae (chickadees and titmice), Sittidae (nuthatches), Hirundinidae (swallows), Tyrannidae (flycatchers), and Troglodytidae (wrens), among others. However, these birds cannot excavate their own cavities like woodpeckers can. They are dependent on existing cavities or artificial nest boxes. Providing birdhouses gives these species a place to nest in areas where natural cavities may be lacking.
Common birdhouse users
Here are some of the most common species that may use birdhouses in North America:
Chickadees
Chickadees, including the Black-capped Chickadee and Carolina Chickadee, readily use birdhouses. They prefer a small cavity entrance no more than 1 1⁄4 inches across. Chickadees nest early in the spring.
Nuthatches
Red-breasted and White-breasted Nuthatches nest in cavities with entrances about 1 1⁄2 inches wide. They often fill a cavity with pine resin flakes or wood chips.
Bluebirds
The Eastern Bluebird and Western Bluebird accept birdhouses with 1 1⁄2 inch entrances. Bluebird houses should have ventilation slots and drainage holes.
Swallows
Tree Swallows, Violet-green Swallows, and Purple Martins will take nest boxes designed specifically for their needs. Swallows nest later in spring and require very large cavities or compartments.
Titmouse
Tufted Titmice use birdhouses with 1 1⁄4 inch entrances. They often nest alongside chickadees.
Wrens
The Carolina Wren builds its nest in any cavity with an entrance larger than 1 1⁄4 inches. House Wrens readily accept small birdhouses.
Flycatchers
Some flycatchers like the Eastern Phoebe nest on shelves inside carports or under the eaves of houses and garages rather than in birdhouses. But the Ash-throated Flycatcher and other western species may use birdhouses.
Species | Entrance Hole Diameter |
---|---|
Chickadees | 1 1⁄4 inches |
Nuthatches | 1 1⁄2 inches |
Bluebirds | 1 1⁄2 inches |
Titmouse | 1 1⁄4 inches |
House Wren | 1 1⁄4 inches or larger |
Choosing a birdhouse
When choosing or building a birdhouse, keep the needs of the target species in mind:
Size
Match the interior floor dimensions to the species. Chickadees and nuthatches need a 4×4 inch floor. Bluebirds need at least a 5×5 inch floor. Larger species like Purple Martins require much more spacious compartments.
Entrance hole
The entrance hole should match the species’ requirements. Make the hole just large enough for the target species to avoid admitting larger, aggressive birds. Avoid perches at the hole, which allow sparrows and starlings to land and take over.
Ventilation and drainage
Ventilation allows air flow and dissipates heat. Drill ventilation holes near the top of the front and back panels. Drainage holes or slits on the floor let rainwater drain out.
Materials
Use untreated, unpainted wood at least 3⁄4 inches thick so it provides insulation. Avoid metal houses, which get very hot in summer. Make sure there are no sharp points or edges.
Predator guards
Metal predator guards or baffles help prevent snakes, raccoons, cats, and other animals from raiding nests. Make sure the guard does not block the entrance hole.
No perch
Avoid perches or landing areas, which allow European starlings and house sparrows to take over. Native cavity nesters can cling to the hole itself.
Where to place birdhouses
Location is key to attracting birds. Here are some tips on where to site birdhouses:
Height
Mount boxes 6-15 feet high to deter predators. Chickadee houses can be as little as 5 feet up. Birdhouses for Purple Martins and swallows can be placed on poles 20 feet high or higher.
Tree or post
Mount houses on tree trunks at least 3 inches in diameter or sturdy wooden posts. Face the entrance hole away from prevailing winds and rains.
Habitat
Erect birdhouses in appropriate habitat for the desired species, like open woods and forest edges for bluebirds or wetlands for swallows. Avoid areas near bird feeders to prevent competition.
Protection from elements
Choose a location protected from harsh sun, wind, and rain. Providing cover plants or vegetation helps shield the house and birds. Turning the entrance away from wind helps.
Territorial spacing
Space boxes for territorial songbirds like chickadees and titmice at least 100 yards apart to reduce competition. Houses for Purple Martins can be in colonies with apartments side-by-side.
Safety
Avoid sites near busy roads or paths. Select areas away from tree branches and wires where predators could perch.
Birdhouse maintenance
Regular maintenance keeps birdhouses safe and sanitary for birds:
Late winter cleaning
Clean boxes out after winter before the new season. Remove old nests and debris which may harbor parasites. Scrub with a wire brush and non-toxic disinfectant. Ensure boxes are secure and not damaged.
Year round monitoring
Check houses regularly to make repairs and remove invasive species like house sparrows. If a house sparrow claims a box, remove and destroy the nest. Monitor chickadee and wren boxes for blowfly infestations.
Autumn preparations
In the fall, prepare houses for winter. Remove nests and clear out materials to allow proper airflow and drainage. Perform any needed repairs and maintenance. You can leave houses up all year since some birds may roost in them over winter.
Build your own birdhouse
Interested in building your own birdhouse? Here are some easy steps:
Materials
You’ll need the following:
– 3⁄4 inch untreated board (like pine, cedar or redwood)
– Saw (hand saw or power saw)
– Drill with various sized bits
– Wood glue
– Hammer and nails, screws, or both
– Paint, stain, or preservative (optional)
Cutting
Cut the wood according to a blueprint for the species. For Eastern Bluebirds, cut pieces at these dimensions:
– Front: 8 x 4.5 inches
– Back: 8 x 4.5 inches
– Sides: 5.5 x 4.5 inches
– Floor: 5.5 x 5 inches
– Roof: 8 x 5.5 inches
Entrance hole
Drill a circular 1.5 inch entrance hole centered about 5 inches above the floor. The hole can be on the front or a side panel.
Assembly
Assemble the box using nails, screws, or a combo. Glue helps strengthen joints. Avoid exterior wood fillers which may contain toxins. Leave a 0.25 inch gap between the roof and walls for airflow.
Finishing
Sand surfaces smooth. Apply eco-friendly stain or paint if desired. Leave the interior untreated. Add drainage holes in the floor and ventilation holes near the roof.
Installation
Install the completed box on a pole or tree at least 5 feet up oriented away from prevailing winds. Add predator guards. Perform regular monitoring and maintenance. Then wait for cavities-nesting birds to arrive!
Conclusion
Birdhouses provide critical nesting habitat for many delightful but cavity-challenged species. Chickadees, bluebirds, nuthatches, wrens, swallows, and other birds will appreciate a well-built and properly sited birdhouse. With good birdhouse management and maintenance, you can attract a feathered family year after year. Observing the birds busily using your birdhouse to raise their young will bring you great joy. By supporting native cavity-nesters, you’ll help contribute to songbird conservation and healthy bird populations.