Barn owls are permanent residents and may nest at any season. Their clutch of five to ten white eggs will produce a varying number of the young, depending on availability of prey. Incubation requires three weeks. The young, which vary in size due to their hatching dates, fly at about seven weeks of age. Barn owls often nest in the same site repeatedly.
Barn owls are considered to be our most beneficial owl, owing to their appetite for animal pests. One once was observed delivering 16 mice, three gophers, a rat and a squirrel to a nest within 25 minutes. An endangered species in Missouri, the barn owl is found worldwide, nesting almost totally in buildings in the Old World and in hollow trees and burrows in much of the western United States. In Missouri, they utilize a variety of sites. Throughout much of its range, the barn owl's numbers are thought to be limited by the availability of suitable nest sites.
Should the beautiful, monkey-faced barn owl accept your box, you will be among the fortunate few. You should reduce human activity near the site and discontinue the use of rodent poisons.