Bluebird populations in the U.S. have dropped drastically because of loss of nesting sites. You can easily help rebuild the numbers while enjoying these sweet, attractive birds that also eat bugs, in rural or suburban areas, even if you do not own land yourself. I offer detailed reference sources, but this Instructable is primarily about lessons I learned myself from decades of cultivating bluebirds, tips you will not find in books. Bluebirds tolerate human presence, and are not aggresive, so it is possible to observe their life cycle up close. They provide a great nature learning experience for children, and youth groups can participate in a community bluebird project. Photo of Eastern Bluebird is from Texas Bluebird Society web page, courtesy of Bill Horn. To see my related Instructables, click on "unclesam" just below the title above or in the INFO box to the right. On the new page that appears, repeatedly click "NEXT" to see all of them.
Step 1: Bluebird House
I lived in my rural neighborhood for over a decade and never saw a bluebird. Someone gave me a bluebird box, I installed it early Spring, and a pair of bluebirds took up residence. I have cultivated the birds ever since, learning how to get an adult pair to produce up to 3 nests and clutches of eggs, up to 15 new little birds each season. As a direct result, I now see bluebirds all around my neighborhood. Bluebirds are very particular about the size, shape, height and orientation of their nest site. Humans have destroyed the naturally-occuring ones, but you can buy or build one that the birds will use and which other birds will not prefer. The baby birds will thrive best if you take care to keep insects and predators from getting to them. A metal pole mount, rather than a tree or electric pole, will help prevent predation by climbing varmints who make their living eating eggs and small birds. The dome, sold as a squirrel guard for bird feeders, does that and also stops snakes, which can climb a smooth metal pole.
Step 2: House Modifications
A bluebird box made of unpainted cedar or redwood will serve for decades, and the birds prefer the box to be about 5 feet off the ground, so you can can easily reach it for observing the birds' life cycle and tending the nest box. This box was designed so that its front panel can be hinged upward. I added the wooden turnbuckles, with compression springs under the heads of their mounting screws, so I could open and close the box for observation and cleaning without having to remove screws. I also added the removable wood block to the front that helps prevent owls or other predators from reaching inside. Two long screws loosely support the block, and it is slid up and off to allow the front of the box to be raised up.
Step 3: Look Inside
The block is removed and the front of the box opened. I thoroughly clean out the box, discard the old material far from the box, then put cedar shavings, bought at pet or department stores, in the bottom of the box in anticipation of nest building. The shavings help repel lice, and they keep flies out of the nest box, which could lay eggs that hatch into maggots that can attack (eat) the tiny birds when they first hatch. The birds add their own nesting material on top of the shavings, and the nestbuilding is distinctive. Bluebirds will defend their nest box against other birds, even outside of nesting season. However, if a nest of another kind of bird appears in the bluebird house, you can simply remove it, repeatedly if necessary, to discourage the interloper. The bluebirds cannot use the box if another bird gets established in it.
Step 4: Birds in Residence
A bluebird will lay a clutch of 4 to 5 eggs, not all of them will hatch every time. Once all the eggs appear, I sprinkle a tablespoon of FRESHWATER (NOT the saltwater type used in swimming pool filters) diatomaceous earth (from eco-friendly gardening supply store) over the top of the nest. This is a non-poisonous material that will kill insects mechanically but not harm the birds, even if they eat it. The pictured hatchlings are losing their fuzz and showing the first sign of feathers. While the adult birds will not be thrilled with someone opening their box, their reaction is just to perch nearby and twitter. Only once has a bluebird buzzed me when I opened the nest box. You can set up a stepstool and allow children to take a quick look in turn, to see the nest built, then a couple weeks later the eggs appear one per day, the hatching a couple weeks later, the rapid growth of the little birds and their final fledging. Once all the eggs are in place, the female will brood the eggs and not want to leave the nest, so it is best to stay away from the box for that couple weeks. During that period, just in case, I give the box a couple taps before I open it, so if she is inside and wants to fly out she will not fly into my face.
Step 5: View With Box Top Removed
Same birds shown with the top of the birdbox removed. Once the hatchlings fledge, they never return inside the nest box. The adults will continue to feed them in perches nearby for a couple weeks. After a clutch fledges, you can thoroughly clean out the box, add fresh cedar shavings if you want, and hopefully the birds will build another nest, lay another clutch of eggs. I regularly have three clutches each season (Mid-Atlantic eastern U.S.) in the same nestbox from the same pair of adult birds, but you must clean out the old nests in a timely manner to encourage new nestbuilding activity. The birds tend to work to an annual schedule, which may vary with yearly climate changes. Have the box ready every year in early spring, then perform your stewardship duties until late summer by watching the birds' activities. The adults will bring bugs to the box when there are young inside, they will stop after the babies fledge.
You can get copius free information about bluebirds from the North American Bluebird Society's web page http://www.nabluebirdsociety.org
and click "Bluebird Facts." Includes size, shape and siting of nestbox, plans for building your own, how to set up a "bluebird trail" on other people's or community land, how to join local chapter. You will not find there many of the practical tips for success I have just given you, though.