Building bluebird nestboxes can be great fun for individuals, families, and community organizations such as Scout Troops. The key to a successful nest box building project is to understand the basics of safe, comfortable, and durable nestboxes before starting the project.
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Eastern Bluebirds examining nestbox with a fiber cement outer roof made of James Hardie siding.
Basics of safe, comfortable, and durable Eastern Bluebird nestboxes:
- Building materials
- Ventilation & drainage
- Physical integrity & weather proofing
The North American Bluebird Society (NABS) publishes a comprehensive set of nestbox specifications on their web site. I strongly recommend reviewing these specifications as the first step of a nestbox construction project. A NABS membership makes a great holiday gift for bluebird enthusiasts.
You can often obtain acceptable nestbox building materials by visiting new home construction job sites and requesting permission from the supervisor to use scrap materials. Avoid using pressure treated wood in your projects due to its potential to harm woodworkers and birds.
Click on the links below to read about pressure treated lumber:
Nestboxes should be routinely monitored during nesting season and thoroughly cleaned immediately after each nesting cycle. In order to accomplish these important steps, you need to provide easy access to the interior of nestboxes.
Front-opening Eastern Bluebird nestbox with hinged door that swings upward. The horizontal grooves under the entrance hole provide a “ladder” for the nestlings to reach the hole during feeding.
Ventilation & drainage
Nestboxes should have proper ventilation for the safety of nesting birds birds during hot weather. One proven approach is to provide narrow roof-line vents under the roofs of nest boxes. This approach will prevent “heat pockets” from building up under the roof similar to what happens in an improperly vented home attic. The floors of nestboxes should provide drainage to remove any water that may enter the nesting chamber. Adding 45–degree corner cuts and a center drain hole to floors is a good approach to providing drainage. Floors should be recessed about 3/4” to prevent “drip siphoning” when it rains.
Eastern Bluebird nestbox with side roof-line ventilation slots to prevent “heat pockets” from building up under the roof.
Eastern Bluebird nestbox with floor drainage provisions including 45–degree corner cuts and 3/8” center drain hole. The floor has been recessed 3/4” to prevent “drip siphoning” and to provide a finger hold to open the door.
Physical integrity & weather proofing
Ensure that all exposed nestbox joints and door seams are tight and do not allow rain water to enter the nestbox. Coat the exterior of nestboxes with a high-quality exterior paint or wood preservative. Light colors are preferred to minimize radiant energy absorption. A long roof overhang at the front of the nestbox provides extra shelter from the sun and rain. The long overhang is particularly useful during the later stages of the nesting cycle when the adult birds feed the nestlings from outside the nestbox.
Adding fiber cement outer roofs to nestboxes using materials such as James Hardie siding is a great way to make them last longer and to decrease nesting chamber temperatures during hot weather. Fiber cement materials resist radiant energy absorption and last for many years when properly installed. Be sure to add a metal locking pin to control unwanted access to the interior of the nestbox. Putting a metal hole protector over the outside of the entrance hole will prevent enlargement by woodpeckers and squirrels.
Eastern Bluebird nestbox with fiber cement outer roof and sloped ventilation slot at top of door. Note the metal hole protector and metal locking pin on the right.
If you have questions regarding Eastern Bluebird nestboxes or would like a copy of the plans and bill of materials for an easy-to-build safe, comfortable, and durable Eastern Bluebird nestbox, click on the link provided immediately below.