Every bird has unique requirements when it comes to their housing. The entrance hole needs to be a certain size, the inner cavern can't be too big or too small, it has to be a certain height above the ground, the proximity to trees or grass or buildings matters. Vary any of these factors and you change the appeal of the house for different birds. By focusing on combining these attributes you can encourage favorite birds to move in.
I'll use the House Wren as an example. Wrens are pretty little song birds common to all of the Americas and can be a great benefit to gardeners. Unlike my nemesis the Magpies which seem to enjoy eating the seeds, berries, and fruit in my garden, wrens primarily eat insects, slugs, and snails. Attracting more wrens improves my pest control plan.
Wrens have very basic housing requirements. A nest made up of twigs, hair, bark, and moss, in a cavity a few meters above the ground is all they need. Building a wooden box and placing it where they can find it is all that's necessary to promote their arrival. So I made some wren bird houses.
I started with a standard wooden fence board that can be found at most big box home and garden centers. A one inch by six inch cedar plank, four feet long (1" x 6" x 4') is enough to make one house. This board will be cut into six pieces, one for each side of the box that becomes the bird house.
There are no fancy cuts or designs. The birds don't care if it matches your home decor or if it has won a design contest. They're just looking for a hole where they can make their nest. This bird house is just a wood box. You can decorate and paint it if you like, but it's not necessary.
The back of the house is 11 inches long; this is the longest piece and provides extra space to secure the bird house to a fencepost or tree. The front and two sides are eight inches long. The floor is four inches deep. The roof is 8 1/2 inches long and provides an overhang to help keep rain out. Lay out the board and mark lines at 11", 8", 8", 8", 4", and 8 1/2" for straight cuts.
On one of the wall pieces a hole is drilled about six inches from the bottom. This is the most important part of building a wren house, or any bird house. The hole needs to be 1 1/8 inch to 1 1/4 inch in diameter and it needs to be a specific height above the floor. Change the size and you change the occupant. If you cut the hole 1 1/2 inches wide you're inviting sparrows, swallows, and bluebirds. Believe it or not, 1/8 of an inch can make a big difference.
At this point you put all the pieces together to form a box. I start by nailing together the floor and one side wall. A pneumatic finish nailer makes the job faster, but finish nails and a hammer will work fine too.
Turn the piece over and connect the other side. Using exterior wood glue at the joints will make the house stronger.
With the two sides and floor together, attach the front piece, being sure to line up and square all edges.
Attach the back piece allowing for an inch to 1 1/2 inch overlap at both the top and bottom. Holes drilled in this overlap is what you'll use to attach the bird house to a post or tree.
To prevent water and moisture buildup inside the house, drill some drainage holes in the bottom. A 1/4 inch drill bit works well.
For extra ventilation, drill a few holes at the top of each side. After drilling the holes shake out extra sawdust from the inside of the house.
The top piece is not nailed into position. One side or the top needs to be removable so the house can be cleaned out at the end of the season and readied for new occupants the next spring. You can make a pivoting side piece where you put pivot nails at the top of each edge and use a screw to secure the bottom. I find it easier to drill holes in the top and connect the top piece with screws so it can be removed as needed.
The birdhouse is complete. Mount it in a tree, under the eaves, or on a fence or wall about two to three meters high and hang out a rental sign for wrens.
You don't need to put a perch at the entrance of the house. Most birds can land on the edge of the hole and climb inside without assistance.
Predators are a definite concern with bird houses. If you mount it on a pole or post you might want to attach a metal guard to prevent squirrels, raccoons, or cats from climbing up. You can also buy predator guards that fit around the entrance hole to keep the same animals from reaching in the nest; attaching another piece of wood with the same hole dimensions to double the entrance depth can work too.
You can find many guidelines and plans for birdhouses online and at the library. I found great information and plans at www. 50birds.com. Enter "how to make bird houses" on google and you'll get millions of suggestions.
If you like birds in your garden and want to attract more, consider building a bird house. It's easy, inexpensive, and encourages wildlife in your garden.
Go to www.50birds.com