Bluebirds are choosy about where they live, and you should be choosy as well about the type of pole you use to mount their houses. Securing your bluebird house to the right kind of pole will help keep the bluebirds safe from raccoons, cats, snakes and other predators. The best type of pole to use is a smooth metal pipe.
Predators such as raccoons can climb trees, fence posts, wooden poles or PVC pipes. The North American Bluebird Society recommends mounting your bluebird house on a zinc-plated electrical conduit pipe or a plain metal pipe. Grease or wax the pole from the ground to about 6 inches from the top with a non-drying automotive grease or carnuba wax. You can also add a domed predator guard to the pole about 6 inches below the birdhouse.
Use an 8-foot length of smooth metal pipe. A 3/4-inch conduit pipe is ideal, but any heavy metal pipe that is rust-free will work. Place the pipe 2 feet into the ground, so that you have a 6-foot height for your birdhouse. Although bluebirds will nest in houses as close as 3 feet from the ground, you are increasing the risk that predators can reach the house if you place them that low.
There are several ways to mount your bluebird house on the pole. One method involves drilling 5/16-inch holes in the pipe and birdhouse, then using 1/4-inch bolts to fasten the house to the pole. You can also use pipe straps or electrical conduit hangers.
To save money, look for scrap pipe at junkyards, hardware stores or metal shops. Before you place the pipe in the ground, use a heavy hammer to flatten the end of the pipe. This precaution will keep the pole from turning around. If you cannot find a metal pole, use a wooden post, but make sure to wrap some metal around the post about a foot and a half below the birdhouse. Grease or wax the metal.