While some birds build nests on tree branches, shrubs, porches, and gutters, others seek an enclosure of sorts. These “cavity nesters” look for or, in the case of woodpeckers, create holes in wood to build nests and lay eggs. Unfortunately, there aren’t enough holes to go around. That’s where birdhouses (also known as nest boxes) come in. They provide valuable homes for many species of birds and a wonderful opportunity for birdwatchers to enjoy viewing the age-old process of breeding.
Here’s what you need to know about birdhouses.
Birds That Use Birdhouses
Among the birds that like a roof over their heads are bluebirds, chickadees, woodpeckers, eastern screech and barred owls, wrens, and nuthatches. Different birds prefer different sizes of the hole (or opening) as well as how high that hole is from the birdhouse floor.
If you live in the city or a populated suburb, you’ll most likely want a hole no bigger than 1 1/4”, which is big enough for chickadees and wrens but too small for house sparrows. House sparrows are an invasive, non-native species that can be detrimental to bluebirds, chickadees, and the like. Download our handy chart for more details.
Birdhouse Appearance and Style
Do any search online and you can find birdhouses in all shapes, sizes, and colors, and made of all sorts of materials. They’ve become a bit of a novelty item. But, to have the most success in attracting birds to a birdhouse, we like to keep things simple.
Birdhouses should be made of wood. Not only is wood durable, but it’s porous enough to allow moisture and heat to escape during the summer, which keeps the young birds from getting too hot inside. Metal and plastic can get too hot, which can cause harm to the birds.
Do resist the urge to get creative. Birds avoid bright, unnatural colors (too obvious to predators). Instead, use natural, unpainted wood and stain the outside with a natural wood preservative such as linseed oil.
Lastly, stay away from any birdhouse with a perch. Birds don’t need them and they only make it easier for predators or unwanted birds to get in.
Placing a Birdhouse
The best time to put up a new birdhouse is in the fall or winter so that birds will have plenty of time to locate them before the breeding season. What type of bird you want to attract will determine where you place a birdhouse.
For example, bluebirds will use houses in open fields; chickadees, titmice, and nuthatches all like the open woods and edges; woodpeckers like forest openings and edges, and so on. For more details, download our nesting chart.
The type of bird may also determine whether you place your birdhouse on a pole or up in a tree. Nuthatches and woodpeckers prefer the latter. Regardless, always mount the house with the entrance hole facing slightly downward to keep wind and rain from entering. And make sure it’s secured so that it does not swing or move.
Before you put up birdhouses all over our backyard, keep in mind that a general rule is to place no more than two houses per species per acre of property.
Fending Off Intruders
Like any house, intruders can be a big problem for baby birds. Squirrels, raccoons, snakes, cats, and house sparrows all can cause harm to eggs and helpless baby birds. Fortunately, there are options to help keep predators at bay.
Many birdhouses now come equipped with predator guards (a reinforcement ring or piece that fits around the opening). Baffles can be placed on poles to keep foes from crawling up.
To keep house sparrows out of bluebird boxes specifically, keep the birdhouse lower than five feet. Tree swallows may also occupy bluebird houses. This can be alleviated by placing two birdhouses 10 to 12 feet apart. Tree swallows may use one while keeping other tree swallows away, leaving the second box open for bluebirds.
How to Care For Birdhouses
Once breeding season is over, usually by mid-August, it’s a good idea to clean out the birdhouse. Remove old nesting material and scrub the house with a solution of one part bleach to nine parts water. Rinse well and leave it open to dry completely.
For birds that have multiple broods per season, like bluebirds, it’s a good idea to clean out nesting material between broods. Keep a close watch on the birds to make sure they have completely fledged (left the nest) before attempting to clean.
When looking to buy a birdhouse, find one that has a side that easily opens. Some even come with a second side the opens to a clear acrylic wall, allowing you to observe the birds without disturbing them. Once clean, it’s fine to put it back up for the duration of the year. In fact, it may be used by some birds for night roosting, and it can provide valuable shelter during extremely cold winter nights.