Unwanted Tenants. Don't let your birdhouses become homes for Starlings or House Sparrows! These birds were introduced into the contiguous United States from Europe during the mids and early 1900s. Both species spread throughout North America and have become serious agricultural and urban pests. In addition, both species compete with native North American birds for cavity_nest sites and thus may harm native bird populations. For example, nest site competition by Starlings and House Sparrows has been blamed, in part, for the population declines of the Eastern Bluebird, a cavity_nesting bird.
Use galvanized nails, as these will not rust. Birdhouses need not be painted, but the box may last longer if you paint the outside. Never paint the inside of a birdhouse. If you paint the outside, use dull (not bright or glossy) colors that blend in with the surroundings. Nest boxes that don't match the vegetation may be easier for predators to find.