2torial #0965:
Learn2 Build a Birdhouse

Follow the nesting instinct

Spring just wouldn't be the same without the sight and sounds of wild songbirds. If you're wondering how to attract them to your home, start by creating a home of their own. With a little research and the right tools and materials, you can build the perfect birdhouse (or nest box, as they're formally known) for your favorite avian friends. With a little luck, you might soon start hearing the new sound of fledgling chicks around the yard.

Birds can be pretty picky about where they'll set up shop, so to build a successful birdhouse, you need to know your potential tenant. Start with a little research on who might be moving in, and when. You can contact your local bird society (such as an Audubon Society chapter), visit your local library or bookstore to read up on what birds nest in your area, or identify species yourself by watching your backyard with binoculars and a bird identification book.

This 2torial details the birdhouse specifications for the more common North American cavity-nesting songbirds, most of which start building their nests between March and May. Ideally, you'll want to have the box ready and mounted before they migrate into your region. Also, a food and water source, natural or man-made, will make your area a lot more attractive. You can usually find all the needed materials--from lumber to tools to birdfeeders, seed, and baths--at a hardware store.

Know your tenant

Even if you've spotted and identified cavity-nesting songbirds on your property, be sure you have the type of area that the bird will feel safe enough to nest in before you invest the time and materials to build the house. Here's a brief rundown of the habitat needs of the more common North American cavity-nesting birds:

Bluebirds like open areas, such as a large yard or field. They usually won't nest in urban areas, since the competition from more urban birds, like house sparrows, is too great. Houses mounted on fence posts or individual poles are ideal, about 4 to 6 feet (1.2 to 1.8 meters) off the ground. For best results, mount houses in pairs, about 10 to 25 feet (3 to 7.6 meters) apart, and 100 to 200 yards (91 to 182 meters) between the pairs.

Chickadees, nuthatches, flycatchers, pygmies, and titmice prefer fairly wooded areas (nuthatches particularly like evergreens, and flycatchers like to be on the edge of a field or stream). For best results, attach the birdhouse to a tree trunk anywhere from 5 to 15 feet (1.5 to 4.5 meters) off the ground.

Wrens are sociable birds and aren't very picky about nesting spots (although they do like low shrubs). They also won't mind if their house is close to yours. Mount it on a tree or post 5 to 10 feet (1.5 to 3 meters) off the ground.

Tree and violet-green swallows like birdhouses attached to dead trees (if possible) about 5 to 15 feet (1.5 to 4.5 meters) off the ground. They like insects, so a house located near a field, pond, lake, or river is ideal. You can also mount these houses in pairs (about 25 feet, or 7.6 meters, between each box, and about 75 yards, or 68.5 meters, between each pair).

Remember, the right placement and box size doesn't guarantee the desired bird will move in. But part of the fun of setting up a house is seeing what develops.

Mark and cut the dimensions

The following chart gives birdhouse dimensions for the more common North American songbirds, with the metric equivalent (in centimeters) in parentheses:

Here's how to use the chart:

First, purchase a board matching the specifications in total board size. Boards are sold according to thickness, width (both of these in inches or centimeters), and length (in feet or meters). While you can use inexpensive wood, such as pine or exterior plywood, more durable woods like cedar, redwood, or cypress will last longer.

Use a ruler and pencil to mark off each section of the birdhouse on the board. Start with the floor size (with half-inch, or 1-centimeter, triangles cut from each corner for drainage holes), then mark the front and back height for the two slanted sides of the house. To save board space, mark the shorter front end, then the taller back end on one edge of the board. On the opposite edge, mark them the other way around, then draw the slant between them.

Next is the front facing piece, which should be 1/4-inch (.6 centimeters) taller than the front height of the side pieces. This is to allow a thin vent on each side of the house to keep the interior cool. To mark the entrance hole, start at the middle of one end of the facing (width-wise), then measure the hole height, bisecting the length of the facing. The spot should be about 2.5 inches (6 centimeters) from the opposite end of the facing. Use the spot as the center point for your compass when you draw the hole.

Note: The box's entrance hole diameter is very specific because particular species prefer particular-sized holes, and because the hole size can protect species from larger, predatory birds, which can destroy or take over a nest.

Finally, the house will need a roof and backing. Use the remainder of the board for both. The length of the backing should be at least 4 inches (10 centimeters) longer than the back side pieces of the box. The roof's length should be at least 2 inches (5 centimeters) longer than the slant of the side pieces.

Once you've marked all the dimensions, make your cuts using a saw. Work left to right, floor to backing. Drill out the entrance hole with a drill and hole saw attachment, and you're ready to assemble.

Start construction and prepare the backing

Before you assemble the house of any bird's dreams, here are a few construction guidelines:

• While a hammer and nails will hold the box together fine, drilling galvanized screws will give a more secure assembly.

• Nails or screws should be inserted about 3 inches (7.6 centimeters) apart, about 3/8-inch (1 centimeter) from the board's edge, perpendicular to the board (unless these instructions say otherwise).

• If you're using screws, pre-drilling pilot holes will make the work easier and cut down on the wood splitting.

• Finally, both nails and screws are easier to insert if you start them before attaching the pieces (that is, mark the spots where you'll nail or drill, insert them until they just pierce through the other side, then butt the pieces together and finish the job).

Start construction with the backing. Insert a row of starter nails or screws along one of the long sides of the backing board. This row should only be as long as the back height of the side piece (the high end of the slant), since the backing board is longer than the side piece. Start the row 1.5 inches (4 centimeters) down from the backing's corner.

Assemble the sides

Once the backing is prepared, take one of the side pieces and lay it on a flat surface, so the short front edge braces against something secure, like a wall, and the longer back edge faces you. Butt the backing board against this end, so the nails in the board line up with the side piece's long edge. The two boards should form an "L."

However, the top edge of the side piece (where the slant peaks) should butt the backing board 1/4-inch (.6 centimeters) below the top of the backing board. This extra space will create an air vent at the top of the side piece. Screw or hammer the pieces together.

The other side piece needs to be attached differently, since it will serve as a swinging door (pivoting from the top, like a dog door), through which you can check the house's interior and clean it out when necessary. To attach it, line up the piece the same way you did with the first--forming an "L" with the backing board, with the top of the slant 1/4-inch (.6 centimeters) below the top of the backing board's edge.

Drill a pilot hole 3 inches (7.6 centimeters) below the top corner of the backing board and screw in a pivot screw. Then hammer a nail so it enters through the backing board and into the bottom end of the side piece. This nail is temporary, so hammer it in only partially, so it holds the side piece in place but can be removed later.

Assemble the facing

Before you attach the front, or the facing, use a nail to scratch about ten 1-inch (2.5-centimeter) wide horizontal lines below the entrance hole on both the front and back side, about 1/4-inch (.6 centimeters)--this will provide climbing traction for entering and exiting birds.

To attach the facing, lay it on top of the "U" formed by the backing and two side pieces. Make sure the top of the facing is 1/4 inch (.6 centimeters) apart above the top of the front side pieces, to provide space for the air vent. Hold everything in place and insert screws or nails into the side piece without the pivot screw. On the pivoting side, insert a pivot screw so it enters at exactly the same height as the opposite pivot screw (to check, measure up from the bottom of each side of the side piece).

About an inch (2.5 centimeters) from the bottom corner of the facing, drill a pilot hole and insert a double-headed nail to hold the swinging door in place. You should be able to remove this nail fairly easily. Insert it at a downward angle, so there's no risk of it falling out.

Add the floor and the roof

Slip the floor piece into the bottom. The piece should be recessed 1/4 inch (.6 centimeters) to keep water from seeping in. Insert it so the two side pieces and facing overlap the floor by this amount. Nail or screw each side into the floor--except the swinging door side piece.

If the roof is wider than the box, make sure the sides overhang by an equal amount. Nail or screw the roof to the backing and facing pieces. Finally, remove the temporary nail from the backing and check to see if the swinging door works properly.

If you've used durable wood, there's no need to paint or stain the birdhouse's exterior (never paint or stain the inside of a birdhouse--the fumes can kill the birds). However, if you've used a less expensive wood, you may want to paint the exterior for more weather protection. Once you're finished, all you need is the right piece of real estate.

Mount the house

Use the guidelines in Step 1 to decide the height and habitat details for mounting the box.

Pole mounting. Smooth poles, such as galvanized steel pipe or 3/4-inch (2-centimeter) electrical conduit, are the best at deterring climbing predators, like house cats, raccoons, opossums, and snakes. Buy enough for the proper house height, plus an extra 1.5 feet (46 centimeters) to bury underground.

To attach the house to the pole, you'll need two pipe brackets that fit the pole's diameter, and four 1/2-inch (1-centimeter) screws. Lay the box so the backing is flat on your work surface, then lay the post so its top butts against the floor of the birdhouse. Attach the brackets to the backing and snugly over the pole, one about 1.5 inches (4 centimeters) above the other, using the screws.

Once it's attached, loosen the screws slightly so you can slip the pole out of the brackets. Take the pole to the spot you've chosen and hammer it into the ground (for particularly hard ground, you may need to dig a hole first). Reattach the house by slipping the pole back through the brackets and tightening the screws, so the house is firmly in place.

Tree mounting. Drill two pilot holes into the backing of the house, below the floor. These should be about 1.5 inches (4 centimeters) apart, one above the other, each big enough for a 1/4-inch (.6-centimeter) diameter lag screw. Position the box on the tree trunk and drill two more pilot holes through the original holes, this time entering into the tree trunk. Insert the lag screws with a wrench, until the house is tightly fixed on the trunk. If the tree is live, you can loosen the screws slightly over time to account for growth.

Protect, monitor, and clean the house

Your responsibilities don't end with setting up the house. To be a good landlord, you have to keep an eye out for your tenants. Here's how:

Protect. To be extra safe, you may want to set up a predator guard, especially if the birdhouse is mounted on wood. For a tree, try wrapping a large band of metal flashing around the trunk below the house. The band should be at least 36 inches (91 centimeters) in height. Punch a hole in each corner of the band, then string wire through the holes to tighten and tie it around the trunk.

For poles, a flat guard (two rectangular pieces of metal flashing, about 36 inches, or 91.4 centimeters, long, sandwiched over and screwed into the pole) works well. Screw the flashing into the pole, then screw the corners of the flashing together using screws and nuts.

Monitor. During the nesting season, you'll want to check the box regularly (about every 2 to 3 weeks) to be sure the right animals are inside it. To do this, simply tap the box so you don't surprise the tenants too much, then flip open the side door gently to look inside. Don't worry about scaring off any new tenants. Cavity-nesting birds can tolerate an occasional disturbance, although they may raise a fuss. Try not to touch the nest, but if you do, don't worry about "ruining" it with your smell. Most birds actually have a weak sense of smell and will return to the nest without a problem after you've left it.

Clean. If the birds have finished for the season, or if you find an unwanted occupant in the box during the season (like snakes or insects), clean out the box. Scoop out any old nesting materials and give the interior a quick blast with a hose. If you leave the house up through the winter, remember to give it another cleaning before the birds come back in the spring.

Once the nesting season is over, you can take your memories with you through the winter, and look forward to your fine feathered friends' return.

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