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Extension Forestry & Natural Resources

Wildlife & Fisheries Biology  -  Environmental & Natural Resources  -  Forest Resources

Birdhouse Basics

Candace Cumming, Urban Wildlife Specialist

Bluebird leaving a nest boxWell, believe it or not, spring is just around the corner, and that means our favorite songbirds and woodpeckers are now looking for suitable nesting sites. Basically, about 85 of our nations 650 bird species use cavities for nest sites. The rest of our bird species build open nests. As a bird or nature lover, you may have already been placing birdhouses out for our cavity-nesting friends, but a quick overview of some birdhouse basics may be in order. First of all, what exactly is a cavity? When speaking in a “bird sense,” a cavity is traditionally defined as a hole in a tree. These natural cavities are usually the result of damage to a tree due to weather or disease. However, some species of birds – especially woodpeckers – will excavate a cavity themselves. We call the woodpecker a primary cavity nester because it creates most new cavities. The ecological result is a supply of once-used cavities for secondary cavity nesters – such as wrens, bluebirds, flycatchers, and swallows – that rely on pre-existing holes. With a decline in naturally existing cavities, along with a reduction in suitable and available trees, many cavity-nesting birds have declined. This is why providing an artificial nesting site is so important. By simply building and placing a birdhouse (or discarded paint can, old mailbox or even a clothespin bag) in a suitable habitat, chances are it will be readily and quickly occupied by at least one species from year to year.

So how do you begin? Which birds use nest boxes? Whether you buy your nest boxes at a store or nature center or build them from scratch, there are certain characteristics your housing should have to best suit the needs of nesting birds. Here are some recommendations for birdhouse basics:

  • Tree SwallowThe lumber should be untreated and at least ¾ inch thick to protect from temperature extremes.
  • Do not paint or stain the inside of the box. If you paint the outside, only light colors should be used to reflect heat.
  • Use galvanized screws to assemble the birdhouse. They will last the life of the box.
  • A birdhouse design which will allow easy access to the inside is a must for nest inspection and maintenance. A side or front panel which swings up is best.
  • Do not add a perch to the birdhouse. These are not necessary. Cavity- nesting birds have strong feet. Perches only give easy access to other birds such as starlings.
  • Scoring the inside of the front panel will give emerging birds an easier way to exit the birdhouse.
  • The floor of the birdhouse should be recessed from the front of the box so that it is not exposed to any rain. Also, drilling 3/8 inch holes in the bottom will allow for drainage if it does get wet.
  • Ventilation holes near the top roof section are a good idea in summer. They can be plugged with putty in the winter.
  • Finally, predator protection in the form of a baffle increases nesting success.
Providing nesting and roosting houses for birds requires some knowledge about the species you are interested in attracting. This will be crucial in determining where to place the birdhouse once you have purchased or constructed it.

Download the printer-friendly version of Birdhouse Basics (PDF, 94 KB)


This article is a publication of Clemson University Cooperative Extension's Forestry & Natural Resources team.
Please visit one of our sites for additional information and educational opportunities:

Extension Forestry & Natural Resources
Department of Forestry & Natural Resources (in the College of Agriculture, Forestry and Life Science)


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