What a good bluebird box needs
Bluebirds nest in cavities, and they readily use nest boxes when natural holes are scarce. Do bluebirds like nesting boxes? Often yes, when the box is the right size and placed in suitable open habitat such as a field edge, a pasture, or a large lawn with scattered trees.
Most extension and bluebird society plans agree on a few features:
- A round entrance hole of the right size.
- A small floor and a modest interior height.
- Drainage holes in the floor and ventilation near the top.
- A rough interior wall so fledglings can climb out.
- A side or front that opens, so you can monitor and clean the box.
- No perch on the front, since bluebirds do not need one and a perch can help predators.
Basic dimensions
Exact numbers vary among published plans, so follow a tested design when you build. As a general guide, using Eastern Bluebird recommendations:
- Entrance hole: about 1 1/2 inches in diameter. Mountain Bluebirds are often given a slightly larger hole of about 1 9/16 inches. See our hole size guide for other species.
- Floor: commonly 4 by 4 inches at minimum; many plans use about 5 by 5 inches.
- Height: roughly 12 inches overall, with the hole several inches above the floor. One Oklahoma State University extension plan places it about 6 to 10 inches from the bottom of the box.
- Drainage: a few small holes, or cut corners, in the floor.
- Ventilation: small holes or a narrow gap between the roof and side walls.
Materials and construction tips
A single rough-cut board, often cedar or pine, can make one box. Some practical tips from published plans:
- Use untreated, unstained wood. Chemicals may be harmful to nestlings.
- Make the roof overhang on at least a few sides to keep rain out and make it harder for predators to reach in.
- Score or rough up the inside of the front wall below the hole, or add shallow grooves, to help young birds climb out.
- Use screws rather than only nails so the box holds together through weather.
- Pivoting or hinged walls make checking and cleaning easier.
Exterior paint should be light in color if used, because dark boxes can get hot. Keep paint off the inside and the entrance.
Where to put the box
How high should a bluebird nesting box be? Many guides suggest roughly 4 to 6 feet off the ground, on a post in open ground with some nearby perches such as a fence or small tree.
What direction should bluebird nesting boxes face? There is no single rule. Common advice is to face the entrance toward an open area, and away from the prevailing wind if you can, rather than following a strict compass direction.
Bluebirds are territorial, so boxes are usually spaced far apart. Some people place two boxes close together to attract a tree swallow to one and a bluebird to the other, which can reduce competition. Check a regional guide for spacing in your area.
Predator guards and monitoring
Mount the box on a smooth metal pole or pipe with a baffle rather than on a tree or wooden post. Predator guards and baffles are widely recommended by bluebird groups.
Check the box regularly during nesting season, ideally once a week, and keep visits brief. Record what you see. Watch for House Sparrows, which can attack bluebirds, and check local rules before removing any nest. Once the young have fledged, clean the box so the next pair can use it.
Where to find full plans
Free printable plans are available from the North American Bluebird Society, which offers designs including the Gilbertson, Peterson and Eastern/Western bluebird boxes, as well as predator guard plans. University extension services, such as Oklahoma State University, also publish detailed plans with measurements and diagrams. Choose a design intended for your region.
Frequently asked questions
Can I make my own bluebird nest box? Yes. Simple designs can be built from one board with basic tools, and published plans include measurements.
Does a bluebird box need a perch? No. Most plans advise against one.
What if I want a different bird? Other cavity nesters need different holes and floors. See our guide to hole sizes by species.