Houses for birds provide nesting sites for birds that require a cavity in which to nest. Primary cavity nesting species (such as woodpeckers) excavate their own sites. Secondary cavity nesters rely on pre-existing cavities. Secondary nesters lack the ability to create their own nesting sites and will readily accept secondary housing.
There are three types of housing categories. The first is considered functional; the second is functional decorative, and the third is for decorative use only.
It is important that functional houses meet the criteria of the proper housing situation for birds. It is important that houses have the following characteristics:
Ventilation
It is important for functional houses to have good ventilation. Panels of wood that are ¾ inches thick help provide insulation from the heat. Holes near the top of the house allow for the heat to escape.
Easy Clean Out
A side panel that opens allows for easy clean out of the nest at the end of the season which helps to keep the pest population down.
Adequate Drainage
Holes at the bottom corners allow for drainage. Drainage holes in the middle of the bottom will not adequately allow for drainage.
Perches
Perches are not necessary and actually allow sparrows and other birds a place to sit and access the hole.
Fledgling Ladder
It is a good idea (especially for bluebird houses) to provide either slashes or a ladder to help the fledglings leave the house.
Functional houses should fit the requirements for the kind of bird that is desired and should be mounted in a manner that is safe for that kind of bird.
Decorative functional houses are often painted or decorated. They should perform as basic houses for customers who wish to provide housing for the birds, but want a more decorative look for their yards. These are also used as decoration inside homes and offices. This category of houses may include houses that are decorated but do not necessarily fill all of the functional housing requirements. It is important for this category of houses to fulfill basic requirements such as ventilation, drainage, cleanout and basic size requirements.
Decorative houses are not functional houses. They do not meet enough of the requirements to be considered proper housing for birds. They should only be used as decoration for inside the home, office, etc. Decorative houses are great for nature lovers to bring a little bit of the outdoors inside.