One of the reasons the bluebird population has increased over the last decade is the commitment of many bird conservationists to build bluebird nest boxes. Because bluebirds are secondary cavity nesters, they don't have the jaw strength to build their own nests and often use discarded nests of woodpeckers and other birds.
Whether you're looking to build your own bluebird house or purchase a bluebird house, you should be aware of the necessary specifications for a successful bluebird nest house.
Entrance Size
Bluebird Nest Box
It's important that the entrance hole in a bluebird house is big enough for bluebirds to get into, but too small for other birds, like starlings. For years, the standard entrance hole for bluebird boxes was 1 and ½ inches. However, recently its been found that some mountain and western bluebirds are too large to fit in these holes. For this reason, the optimal size has been revised to 1 and 9/16 inches.
Opening location
Bluebird boxes either open from the side, the front or the top. All options have their advantages and disadvantages. Boxes that open from the top are generally easier to monitor, while boxes that open from the side or front are easier to clean.
Floor Size
It's crucial that bluebirds have adequate space to nest in. The standard area for a bluebird box used to be 4 inches by 4 inches, but it is now recommended that bluebird nest boxes have a floor space of 5 ½ inches by 5 ½ inches. Mountain and western bluebirds sometimes lay up to 8 eggs and require this additional space.
Material
While bluebird houses are constructed from a variety of materials, the consensus is that wood is the best material to use. Not only is it similar to natural bluebird cavities, such as holes in trees, but it is also inexpensive and chemical-free. There are a number of different opinions regarding the use of wood preservatives, but it is generally recommended to avoid pressure-treated lumber. If you want to stain your blue bird house, you should only apply finish to the outside of the box. You should also use a light finish, as dark finishes will make the box hotter. One recommended stain is linseed oil.
A number of other materials are used every year to construct bluebird houses. PVC pipes are one of the more recent innovations and are affordable and easy to work with.
Insulation, ventilation and drainage
Bluebird House
It's important to protect bluebirds from the elements. If a bluebird nest box is soaked in water or becomes too hot ( over 107 degrees Fahrenheit), the eggs can be damaged. Using wood that is light-colored and a minimum of 1-inch thick is a good way to protect your nest from excessive heat.
You should also drill a ventilation hole with a diameter between ¼ and ½ inches on either the top or the sides of your bluebird house. A ¼ inch hole should also be drilled in the bottom of the house to drain out any water that gets in your blue bird house.
What else about bluebird houses?
It's also a good idea not to put a perch on the front of the box, as this may attract house sparrows. Lastly, make sure you have an overhang that sits 1-2 inches over the hole to provide shade for your bluebirds and to keep the rain out.
Want to learn more about bluebirds? Check out one of the related articles below. You can also browse our huge bluebird house collection, if you're ready to get started with bluebird feeding today.
Ready to purchase a bluebird nesting box? Check out our bluebird house collection. Want to learn more about bluebirds? Check out the other articles below.
