For a real treat in your yard or garden this year, try putting up a bluebird house. These gorgeous birds are so sweet and charming, swooping from tree to post to guard their nests and see what you're up to. And if their stunning beauty weren't enough, they're also great for natural summer insect control!
Setting up and maintaining a bluebird house properly can take a bit of attention, but it's really quite easy. Follow these tips to get started.
About Bluebirds and Bluebird Houses
Bluebird nesting season starts between February and April, depending on the weather, and goes until August. Some areas have bluebirds year-round. They usually raise at least two broods of three to six eggs per year, with the babies fledging about four to five weeks after the eggs are laid. While spring is the best season to install a bluebird house, you can do it any time.
When shopping it's important to buy an actual house made for bluebirds and not a decorative bird house. The house has to be built just right in order to attract bluebirds and keep them safely, while deterring other competing birds.
Thankfully, most commercial bluebird houses are built to the proper specifications, but when in doubt be sure that your bird house has these characteristics:
- Well Built: A bluebird house should be watertight, yet ventilated and with drainage holes. It should be built of a rot resistant wood, like cedar, or untreated exterior plywood. You can paint the outside a light, neutral color or coat it with linseed oil, but the inside should be untreated wood.
- No Perch: Perches encourage competing birds and predators.
- Right Size: Most bluebird houses are around 5” wide and deep and around 8” to 12” high, with an entrance hole about two-thirds of the way up.
- Proper Opening: The opening is the most important factor for keeping out competing and predatory birds. Round openings should be 1 3/16” to 1 1/2” inches in diameter. Slot entrances should be 13/16” to 1 1/8” wide. Oval entrance holes should be vertical, 1 3/8” by 2 1/4” high.
- Easy to Monitor: Most bluebird houses have a hinged top or side that can be opened to check the nests and clean them out during the off season.
How to Install a Bluebird House
Bluebirds like fairly open areas, with scattered trees for perching. Organic farmland is perfect, with open spaces bordered by fences and tree lines.
In more developed areas, bluebirds are likely to be found around large open lawns, quiet roadways, old railroad paths, parks, cemeteries, golf courses, new housing developments, and neighborhoods on the edge of cities. They usually don't hang out in heavy woods or city centers.
When installing a bluebird house, consider:
- Location: While scattered trees or shrubs are fine, choose a fairly open spot away from woods.
- Mounting: A pole or fence post is ideal, especially if you can add a baffle to keep out predators such as cats, snakes, and raccoons. Mount the house at around 5’ high, so that you can easily reach it to monitor and clean.
- Orientation: Ideally, face the opening toward a safe perch, such as a small tree or fence. Also try to face it away from prevailing winds, and away from midday sun in hot climates. If you are installing the house near a road, face it parallel to the road, so the birds won't fly out directly into traffic.
- Spacing: Bluebirds are competitive and usually claim two or three acres, so be sure their houses are widely spaced. Eastern bluebird houses should be 100-150 yards apart, and Mountain and Western bluebirds should be over 200 yards apart.
- Organic Garden: Since bluebirds eat insects, they can provide natural insect control, but avoid areas with heavy application of pesticides.
Dealing with Competitors
One of the biggest challenges to bluebirds is the threat of other birds competing for the nesting space. European starlings and house swallows pose the largest threat to bluebird nesting, and these non-native birds will attack bluebird nests and destroy the eggs.
You can reduce the risk by making sure your bluebird house has the right size opening (to keep starlings out), and locate it away from urban areas, houses, and barns (to deter house swallows).
Native competitors – such as tree swallows, titmice, house wrens, chickadees, and nuthatches – are beneficial birds and can be encouraged to nest by installing the house a little higher (10 feet or so) in a wooded spot.
Tending a Bluebird House
Once you've got your bluebird house in place, a little attention throughout the season will keep it safe and snug for repeated broods of eggs. Clean your box every February before nesting season starts, and repair any damage. Then, clean and brush out the box in between each brood of eggs, making sure to throw away the old nesting material to get rid of any disease or parasites living in it.
If you monitor your bluebird house, be sure not to open the box after the babies are about a week old, and leave it closed until they fly – you don't want them accidentally leaving the box too early.
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