Bird houses are more than just decorative accessories. With the acreage of natural woodland getting smaller, birds are having trouble finding natural places to nest or get out of inclement weather. The type of birdhouse, or houses, you choose to buy or build depends on the type of birds in your area. Each species has its own needs.
Purple Martin Birdhouses
Purple martins are migratory birds that will return to the same birdhouses year after year. They travel in colonies, so purple martin bird houses need to be able to accommodate more than one bird family. They are the apartment houses of birdhouses, having anywhere from 8 to 28 individual living areas. Purple martin birdhouses should have door stopper-plugs that close the opening so other birds cannot take over while the martins are down south. They can be made of aluminum or any other material that is lightweight and can stay cool. There should be a perch outside each entrance.
Blue Bird Birdhouses
Blue bird birdhouses should be made out of cedar or redwood. Other types of wood can be used as long as they are a minimum of 3/4 of an inch thick. The wood should be untreated to avoid toxins that can harm the birds. The measurements are different depending on the part of the country because blue birds differ in size from one area to another. In the eastern time zone they should be about 4-by-4 or 5-by-5. The holes should be 1 ½ inches round, 1 3/8-by-2 ¼ vertical oval holes or 1 1/8-inch horizontal slots. Oval holes are only used in the east because they are small enough to keep starlings from sneaking in. In the western and mountain zones, they have to be bigger, at least 5-by-5 inches to 5 ½-by-5 ½ inches. The blue birds here lay more eggs and have more hatchlings. In the mountain zone, the entrance should be 1 9/16 inches, and in the west 1 ½ inches round. There should not be any perches on blue bird houses. Blue birds do not need them, and it would only make it easier for other birds to gain access.
House Wren Birdhouses
House wrens like their houses to have a snug fit. They should also be put near shrubbery, not out in the open. They also like to nest close to the ground. They will accept a house that is placed between 5 and 10 feet above the ground. It should measure 4 inches wide, 4 inches long and 6 inches high. The entrance should be 1 1/4 inches in diameter, big enough for the wren, but small enough so an English sparrow cannot get it. The entrance needs to be 4 to 7 inches above the house floor. Wren birdhouses should be left hanging, as opposed to being nailed to a post, tree or wall.