1. Hole: get as close to 1 1/2" as you can.

2. Interior dimensions: 4" x 4" x 10" high.

3. Bottom should be recessed 1/2: with cut corners to ensure dryness.

4. Blunting nails by striking the point with a hammer will minimize wood splitting.

5. Ring shank nails or galvanized screws are preferred.

6. Two-inch overhang on top, good steel post with metal flashing to discourage predation by cats, raccoons, and snakes.

7. Place box in open away from brush and trees to discourage wren nesting.

8. Bottle gourds provide adequate alternative nesting cavities for wrens.

9. Face bluebird box opening toward bush or tree or some structure within 50 yards for fledglings' first flight. Avoid facing box to the north.

10. Redwood or cedar is good wood. Paint pine wood a light-colored earthtone.

11. House sparrows are not protected by law. Boxes placed away from buildings, feedlots or typical English house sparrow haunts are best.