NOTICE: Please read all directions before beginning any new woodworking project!
Scrap lumber of nearly any kind can be used to build a squirrel den box. Exterior-grade plywood may be used, but squirrels may destroy the box by gnawing the plywood. The main items to consider during construction are the cavity size and entrance hole. The cavity should be a minimum of 6 x 6 x 20 inches, and the entrance hole must be at least 3 inches in diameter, located about 2 inches from the top. The hole is located next to the side which will be placed against the tree trunk. The top must be weatherproof, and the bottom should have a small drain hole to allow moisture to escape. Experience has shown that the bottom will deteriorate within about five years unless the box is cleaned at least every third year.
Excelsior, dry sawdust or leaves should be put in the bottom to encourage use. The bottom or top may be hinged for periodic cleaning. The box should be placed 10 to 30 feet high in tree tops. Use aluminum nails to secure it. Wire is not recommended, since it can girdle the tree, but if wire is used it should also be aluminum or copper to prevent damage to saws. The den box should be placed with the hole near a limb to allow easy entry. It also is best to face the entrance toward the south, away from prevailing winter winds. Boxes placed at or near the edge of large, forests are more attractive than those placed 100 yards or more inside the stand, especially to fox squirrels. Boxes are used most heavily in the winter; therefore, they should be installed during the fall. A good cypress or cedar den box will last ten years or more and furnish a home for about 20 families, housing nearly 75 squirrels in a decade of full use.
Studies of leaf nests show that each pair of squirrels requires three dens--one for the male, one for the female and another in which the young will be born. The pair will live in one den until just before the young are born. At this time, the female will evict the male, who will then require an additional den or nest. After the young leave the nest, the male will rejoin his mate. The young will require more dens, of course, as the population increases. If none are available, they will either migrate to another area or will be eliminated by predation.
Other animals commonly found using den boxes are kestrels, screech owls, honey bees, some woodpeckers and even blacksnakes. In addition, crested flycatchers and other songbirds have been known to use the squirrel den box for nesting.