Alfaleith.org - Eastern Blue Bird Nest Box

At one time the Eastern Bluebird nested in cavities in wooden fenceposts and old trees. When urban sprawl, the clear cutting of hedgerows, and modernization of fencing began to take hold, they began to lose nesting sites, and introduced species such as the starling and English sparrow out-competed them for space. Their population fell in these past few decades to 10 percent of what it once was. And the insect population has not only increased but has begun to be found carrying strains of foreign disease, such as Newcastle's, West Nile, and so forth. However, with some truly green human intervention they are making a comeback, and may be enjoyed again not only for their beauty and song, but also for the sheer amount of insects they consume. Along with bats, tree swallows and martins, they rank high for reducing the mosquito population, as well as taking the more destructive species of tent caterpillars and flying beetles.

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This box is built from one 1x6x8 cedar or pine board. Cedar lasts longer, and its surface gives a toe hold for bluebirds as well as tree swallows. (The actual dimensions of a “1x6” board are about ¾” by 5 ½”.)

Sides: Cut two 8 inch long pieces.
Back: Cut one 14 inch long piece.
Front: Cut one 8 inch long piece four inches wide.
Bottom: Cut one 4 inch long piece, and cut about 3/8” off each corner, for drainage.

The front should have a 1 1/2” hole drilled about 1 1/8” from the top. The front is not nailed on but held in place with finish nails about one half inch down on both sides of the top, and one finish nail on one side on the bottom. The bottom nail should be long and stick out from the frame. This way you have a hinged front you can open and clean after the season is over, and after winter before the season begins.

If you have predators such as raccoons, a second piece 3” x 3” can be cut with the 1 1/2” hole drilled in the middle, and mounted over the opening. This makes the reach too long for bandits.

Finish the box with a coat of dull coloured stain, or leave it to grey out naturally. Don't use wood preservatives, and don't paint it white, this attracts house sparrows, (who are beneficial in their own way but not our goal). Don't stain the entrance hole or the inside of the box.

Place boxes four to six feet high. Don't go any lower, you will encourage predators to explore. This height also discourages sparrows. To encourage bluebirds, place boxes in open meadows near emergent growth forests, or in an open wilder area of your backyard, preferably backed by hedges or shrubs. Bluebirds enjoy mowed fields and open grassland, (while swallows will skim ponds and low lawns). Placing two or three at least five yards apart is also preferred by the birds, and many bluebird trails across the northern United States place them one hundred yards apart, stretching for miles. .

Tree swallows will also use these boxes. You can identify their nests by the nesting materials they choose. Bluebirds always weave nests of fine grasses, from three to four inches deep. Swallows gather thistle down, spider webs, courser grasses and straw, and most telling, feathers. They will use chicken, goose and peacock feathers if available, as well as dog fur and horse hair. Either species consumes millions of mosquitos, gnats, and flying insects per season.

The eggs of the bluebird are pale blue, (seven percent are white), about 5/8” long, and there can be up to six in a nest. Swallow eggs are pure white. Both parents feed the young from sunup to sundown until they are fledged, about twenty days. After they have flown, she will begin a second nest. You can feel free to check on them during incubation and rearing, being careful to open the box slowly. Make certain that yellow jackets and paper wasps aren't trying to take over the box while they stand empty, the birds won't nest where they have. Also make certain there aren't any signs of deer mice or flying squirrels doing the same, although if you wish to encourage the flying squirrels, leave them alone and just build more boxes for the birds.

Make certain the eggs have not been tampered with while the parents are away. Two potential problems are the cowbird and the wren. The cowbird does not build a nest of her own, she will lay her egg in any available nest, often the open nests of cardinals and jays, but sometimes also in a bluebird box. The egg will dwarf the bluebird or swallow egg, and when the egg hatches, the chick will so far outsize the young bluebirds or swallows that they will lose the competition for mother's food, and the unhappy couple will raise the demanding cowbird chick until maturity. The wren's peculiar nesting rituals include the cock bird building several nests, which are built of heavy sticks and twigs, in various places around an area. He brings his mate around to each one, showing off his clever workmanship, (which can range from twigs stuffed into old coffee cans and boots to mailboxes and drainpipes) until she settles with one that suits her fancy. She will then explore the territory for any other species' nests in the area, and break every egg she finds, in this way cutting out the competition for food. They are especially cutthroat when it comes to bluebird boxes. If you find even one or two heavy twigs in a bluebird box, remove it immediately and keep an eye on your boxes for a week or two. (Unless you enjoy wrens. In this case, you may need to join a support group. Author's opinion only.)

During winter, even in the far north, bluebirds may decide not to migrate if their habitat contains enough late season berried shrubs and trees. If they do decide to stay, they will pile six or seven, or more, adults at a time into a box to keep warm during the snows, and supplementing their diet during this time with raisins, suet, dried fruits, and even mealworms at the feeders will keep them comfortable. Make certain you take a tour of the boxes in very early Vár to clean out the old nests and do any repairs necessary for the upcoming season.