What to look for in a Nesting Box

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 carried by most Wild Birds Unlimited stores. The first is considered functional; the second is functional decorative, and the third is for decorative use only.

Functional Houses

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:

Entry Hole

The size of the entry hole, the distance from that hole to the floor and the inside dimensions must suit the bird you want to attract.


For the proper insulation, wood should be at least ¾” thick; recycled plastic should be at least ½” thick.


It is important for functional houses to have good ventilation. Panels of wood that are ¾” 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. (The Wild Birds Unlimited houses allow for viewing or photographing of the birds without disturbing them by offering a top opening panel.)

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 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. Consult the Wild Birds Unlimited Housing Guide (available at Wild Birds Unlimited stores) for more information.

Decorative Functional Houses

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

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.