The natural cavities that owls choose are typically 12 to 20 feet above the ground and in deep shade. As the female incubates the eggs, the male is apt to spend the day roosting in dense foliage within about 20 feet of the nest . The hole size on this cedar owl/kestrel house is 3". It has a front opening for cleanout and is well ventilated. Measures 9" x 12.5" x 20".