The Neighborhood Gardener
Helping Cavity-Nesting Birds
Gardeners love to have birds and wildlife in their yards. More than 25 bird species in Florida require cavities or holes in trees as nesting sites, and you can help bring those birds to your yard.
Some cavity nesters such as woodpeckers, Carolina chickadees, American kestrels, and brown-headed nuthatches prefer to excavate their own nest cavities in dead or decaying wood.
Nest sites for these birds are usually in shorter supply than food and water. Dead trees, or snags, are often removed from forests, parks, and yards. Whenever, possible, try to leave some snags for birds.
You can also build nest boxes or birdhouses that mimic natural cavities. Birdhouses can be set out at any time of year, but making them available just before the major nesting season will enhance their use. The major nesting season is March to June so try to have your birdhouses set up by January or February.
The following general considerations apply to all birdhouses:
- Cleaning – Include a hinged door or other means for easily checking and cleaning out the house. Birds will do their own cleaning as they do in natural cavities, but your help will increase use.
- Drainage – The bottom should contain 3- or 4 1/4-inch holes to allow drainage of rain water that may enter.
- Attachment – Houses built for wrens can be suspended under an eave or a tree limb. All other houses should be firmly attached to a post, tree, or building.
- Perches – Natural cavities do not have perches, so do not attach perches on any built houses. Perches will only encourage use by exotic English sparrows and European starlings. A nail or knife can be used to scratch the outside surface below the entrance if smooth boards are used. Cavity-nesters perch on vertical roughened surfaces such as bark.
- Roof – The front edge of the roof should overhang about 1-2 inches to help protect the entrance from wind-driven rain.
- Ventilation – Ventilation holes or slits should be located at the top of both sides just beneath the roof.
- Nails – Use galvanized nails.
- Floor – The floor should be situated between and about 1/4 inch above the bottom edges of the front, back, and sides. This will help prevent the rain from seeping into the bottom of the nest.
- Wood – 1" x 4", 1" x 6", or 1" x 12", untreated boards are the best materials to use.
- Paint – Newly painted or oiled houses are less attractive to birds until they have weathered. However, for the purple martin houses, paint the top surfaces white to reflect the sun's heat.
- Style – The shape and style of the house are not as important as the dimensions.
- Size – House dimensions should be close to those given in the EDIS document, but they do not have to be exact.
Read more about cavity-nesting birds in Florida and their habitats in "Helping Cavity-Nesters in Florida."