University of Maine Cooperative Extension
Bulletin #7117

Birdhouse Basics

Birdhouses are an easy way to have more birds around your home or in your woodlot. In this fact sheet, we explain how to build houses for different kinds of birds and provide tips for setting them up.

As lands become more developed, birdhouses become more important. On the back side of this fact sheet is a pattern for a birdhouse, and a list of measurements so you can adapt the pattern for different species. Tailoring the house you build to the needs of species you want to attract will increase your chances of success.

For all houses, here are some general guidelines:

1. Provide a hinged side or roof so you can easily clean the house each spring—early March is a good time. Use rust-proof hinges to make the task easier. Keep in mind that raccoons can open a hook and eye!
2. Drill at least four 1/4-inch drain holes in the bottom of every house, and two 5/8-inch ventilation holes near the top of each side of the house.
3. Provide a roof with at least a two-inch overhang on the front to protect the entrance hole from wind-driven rain, and to prevent cats from reaching in from above.
4. The sides of the house should enclose the floor to keep rain from seeping into the house and nest. Recess the floor 1/4-inch up from the bottom to further prevent rotting caused by moisture.
5. Don’t put perches on any bird house. (Take them off houses that you purchase.) The only birds that prefer them are starlings and house sparrows.
6. Keep entrance holes on songbird houses 1 3/8 inches or smaller to keep out starlings and house sparrows. (Purple martins are an exception.)
7. Space boxes at least 25 feet apart (300 feet for bluebird houses) to reduce conflicts. Most birds are territorial and protect the area around their nests. Goldeneye mergansers and wood ducks are not territorial, so you can place their houses closer together. Purple martins live in colonies and prefer “apartment houses” to single-family houses.
8. Wood is the best material to use. Avoid pressure-treated lumber because when it gets wet it can give off vapors that are poisonous to birds. Preservatives, such as paint or stain, can be used on the outside of the box, especially the back, but not on the inside. Avoid using creosote as a preservative. 
9. Do not use tin cans, milk cartons or metal for nest boxes. They can overheat and kill the eggs and young birds. The only exceptions are commercial aluminum martin houses.
10. Other animals may take up residence in your boxes, including mice, squirrels, bees and wasps. If unwanted, remove them (be very careful not to get stung!), otherwise put up a few extra boxes to make room for both the expected and unexpected tenants.
11. House sparrow and starling nests and eggs can be removed, as they are not protected by state or federal law. You may need to be persistent, removing the nest repeatedly until the birds finally give up.
12. Most houses should be attached to a post, building or tree. Bluebird boxes should not be placed on trees because of cats and raccoons.
    

Diagram for tree swallow, Eastern bluebird and great crested flycatcher nest box.

Illustration recreated from art supplied by the Minnesota Department of Natural Resources.

Prepared by Catherine A. Elliott, Extension wildlife specialist 

For more information contact your University of Maine Cooperative Extension county office.

Published and distributed in furtherance of Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the state of Maine and the U.S. Department of Agriculture cooperating. Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

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