It's spring, and a pair of bluebirds is prospecting around your yard. You have a box, and you want to put it up in a hurry. Why not just nail it to a tree? At all costs, resist the temptation to bang a box onto the nearest tree or fence post. Mounting your bluebird box properly will save you future expense and heartache and possibly save the lives of the bluebirds.

It's hard to beat an 8-foot length of 3/4-inch (inside diameter) galvanized pipe (available at plumbing supply, hardware, or lumberyards) for mounting bluebird boxes. When you mount a box on free-standing pipe, you free yourself to put it wherever you like, in the best place for bluebirds. It won't rot like wood, and its small diameter makes it easy to mount predator baffles. If you need to grease the pole to stop climbing ants, you can wipe off old and apply new grease on the non-absorbent metal. The 8-foot length lets you sink two feet in the ground, and mount the box at eye level, which makes it easy to check. Even pipe, however, affords no protection from climbing raccoons or snakes, so you'll need to fit it with a baffle (see "Predation").

There are a few ground rules for siting a bluebird box. Most important is to keep the box as far away from shrubbery and treelines as possible. House wrens, which are highly destructive competitors for boxes, are reluctant to cross open spaces. If possible, site the box l00 feet or more away from cover. Bluebirds greatly appreciate additional perches in vast expanses; these perches can simply be stakes or tree limbs stuck in the ground. Adding a few places to perch can enhance a box's attractiveness at no expense.

Mount the box about five feet off the ground, or so that the bottom of the box is at your eye level. This is high enough to foil most leaping cats, and low enough to make it easy for you to monitor nests. The baffle should go right under the box. Face the box away from prevailing winds, which generally means facing it south. If you need to fudge a little to make it easy to see the hole, the birds won't mind.

Although bluebirds appreciate boxes year-round, you'll want to have them up by February in the south and March in the north, to catch the eye of returning migrants. Keep in mind that in the winter, bluebirds often roost in boxes. I use flexible putty weatherstripping (Mortite) to caulk all ventilation holes, and I don't remove it until the weather is reliably warm. It's vital that the box stay dry inside at all times, for even an attentive bluebird mother can't save eggs or young in a soaked, cold nest.

It's a great idea to have a spare box or two on hand. If house wrens or swallows oust your bluebirds, if an old box becomes soaked, or if another bluebird pair shows up where you have but one house, you can quickly erect a spare. Where tree swallows are abundant, you may wish to pair your boxes, 15 to 25 feet apart.

Picture a perfect farm scene, and it might include bluebird boxes on fence posts, or nailed to the old apple tree. I learned the hard way that both these classic methods of mounting nest boxes create potential deathtraps for bluebirds. Ten years ago, my first bluebird boxes were nailed to trees in my yard. All went well that first year. But the second year, the local raccoons and black rat snakes learned that an easy meal awaited them in my boxes, and a brooding female and several broods of young went to them instead of into the skies.

Many people who have a number of bluebird boxes to monitor consider predation a natural part of the scene, which, of course, it is. But a distinction should be made between bluebirds that nest in natural cavities and those attracted to artificial sites. How many times have you walked right past a woodpecker hole high in a tree and never noticed it? Can you say the same of a nest box mounted on a tree, fence post, or pole?

Now imagine you're a grizzled old raccoon or black rat snake, veteran of many years of searching for birds' nests hidden in almost every imaginable situation. You know to watch for parent birds carrying food, to listen for or sense the shrill pipings of nestlings. Just once, you follow these cues to a wooden box, and are richly rewarded for your climb. A meal, and a package, to remember. And the nest boxes in your territory become predator feeders.

In attracting bluebirds away from cryptic natural cavities to conspicuous nest boxes, we are in a sense setting them up for predation. The incubating female, potential mother to dozens of offspring, might slip unnoticed into a tree hole, but less secretly to a box out in an open field. She is at special risk, and her death impacts the breeding potential of a local population.

Should we put up nest boxes at all? Yes, but only if we accept the responsibility that goes with them, to monitor and protect them from predators. As I continued to work with bluebirds, my learning curve continued to rise, albeit slowly. Reluctant to take my boxes down, I took the easy way out. I put hole-mounted "predator guards" on the boxes, a 1-inch thickness of wood that effectively deepened the box entrance to 1-3/4 inches. In theory, a raccoon would be unable to reach through this thickness and then down to grab the birds. No one told the 'coons, though, and if it was a little harder to get the reward, they simply kept at it, or chewed the guard off. Needless to say, the snakes were unfazed. I thought about the terror a mother bird must experience as a raccoon chewed its way through her door, and I decided that mounting a predator guard on a box hole is like putting an ambulance at the bottom of a cliff. Once the predator is on the box, there's very little hope for the bluebirds inside. Off came the boxes on trees and fence posts. Out to the plumber's supply to buy 8-foot lengths of 3/4-inch (inside diameter) galvanized pipe, and strapping brackets to be screwed into the back of the boxes. I settled on 30-inch conical sheet metal baffles, kept in place under the box with hose clamps above and below the baffle neck. The predation stopped cold, and maintaining bluebird boxes turned from a guiltfest into the pleasure it ought to be.

The big baffles had some drawbacks. They had to be removed at the end of nesting season, lest they self-destruct in winter winds. The boxes had to be removed to take them off. They were big and cumbersome. Baffles made of plastics simply broke down in sun and freezing temperatures.

I decided to run tests of other baffles. I began setting table scraps out on a platform bird feeder, and soon raccoons were coming nightly. They climbed the galvanized pipe with ease. Grease did nothing to stop them, for it soon hardened and got sticky. (Even fresh grease won't stop snakes). PVC pipe was easily climbed; they simply gave it a bear hug and shinnied up. The same went for a cedar post wrapped with sheet aluminum.

Finally, I found a baffle that worked, that was easy and cheap to make, and that didn't have to be removed. It's just a 24-inch section of galvanized stovepipe, 7 inches in diameter. For roughly $6.00, you can ensure safe nesting for bluebirds, and disappoint raccoons, snakes, cats, opossums, chipmunks, and mice. It should be mounted just under the box.

How to make this Baffle:

Materials used: galvanized pipe 3/4" inside diameter, strapping brackets and weatherproof screws (to mount box to pole), hardware cloth (1/4" mesh), machine screws with nits, hanger iron (in two 7" strips), galvanized stovepipe 36" x 8").

With tinsnips, cut the hardware cloth into a circle 8 inches in diameter. Place it over the stovepipe, bending the edges down so that it will fit snugly into the pipe, about an inch down from the top (A). Close any gaps between hardware cloth and stovepipe otherwise snakes may squeeze through.

Next, use tinsnips to cut three tabs (B) in the top of the stovepipe. Bend these over the hardware cloth. Cut a small hole in the middle of the cloth to allow the assembly to slip over the box mounting pipe.

Bolt the two strips of hanger iron (C) securely on either side of the mounting pipe, and bend them to support the hardware cloth. Duct tape wrapped around the pole helps hold the hanger iron in place. Slip the assembled baffle over the hanger iron bracket, just below the nest box. It should wobble a little, which further discourages climbing predators.

Many people who feed bluebirds offer a mixture sometimes called Miracle Meal. A basic recipe is:

4 cups yellow corn meal
1 cup all-purpose flour
1 cup lard or melted suet
1 teaspoon corn oil
Plus sunflower hearts, peanut hearts, chopped, soaked raisins.

Melt lard and stir in other ingredients. Spike with sunflower hearts, peanut hearts, or chopped soaked raisins, as desired. Let set, cut into chunks, feed as suet.


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