A wren house is a typical birdhouse. The same type of birdhouse can be used by many small wild birds, including sparrows and bluebirds. To build a generic wren house, follow the simple steps below.
Step 1: The Basic Wren House Design
A simple wren box consists of 1 long side, 1 short side, and 2 sides that are angled from back to front. These pieces form the walls of the wren house, and a fifth piece forms the floor. In the front (or short side) of the box, you will need to cut a hole for the bird use, and provide a small dowel for birds to perch on. Place a top on the box, and mount it on a post.
Step 2: Cut the Parts
A birdhouse for wrens does not have to be very large. Cut the longest piece 12 inches long and the shortest piece should be 10 to 11 inches long. Cut the side pieces at an angle, taller on the back and shorter on the front, matching the length of the front and back.
Measure 4 inches down from the top of the front piece and drill the hole. Bevel the edges of the holes with sandpaper.
Drill a hole the size of the dowel. Install the dowel with wood glue. You can cut the bottom piece later to make sure that it fits properly in the hole it will fill.
Step 3: Build the Box
Use finish nails to tack wren boxes together. Fit the sides against the inner edge of the back, and then close the front by attaching the inside edge of the front wall to the short points on the sides. Mark and cut a piece of 1x6 to fit inside the bottom opening, and nail it into place as well. Center the piece of plywood on top of the birdhouse, and nail it down.
Step 4: Finishes
Paint or finish the material as you want it to look. Keep in mind that paints and stains contain chemicals that could be harmful to wrens and their eggs. If a wren senses dangerous chemicals, they won't use the box, and your effort will be wasted. For best results, allow the box to weather naturally.
Step 5: Mount the Wren house
Be sure to mount the birdhouse above the reach of ground animals. Additionally, avoid placing it below tree limbs where predators could swoop down on it. The best method is to place a post in a relatively remote area, with plenty of sunshine and an open field of view. Mount the birdhouse on the post so that it faces south or east.