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.
Clean the house seasonally or whenever a family of birds vacates the premises: Remove all nesting debris and rinse the house with a sanitizing solution of one part bleach and nine parts water. Rinse the house again with clear water, and allow it to air dry thoroughly before storing it for the winter or repositioning it for new tenants. Nesting birds face many different hazards, but there are easy ways to make any bird house design safer and more attractive to bird families. Building a bird house may seem like an easy project, but there is much more to an attractive, bird_friendly house than a wooden box with an entrance hole. Before you build a bird house, you need to understand what nesting birds need and how best to meet those needs with the house you construct.