Renewable eucalyptus wood with teakwood finish is the perfect choice for quality bluebird shelter; an environmentally friendly and an ultimate renewable resource. The hole size (1-9/16") is specific to bluebirds and prevents larger birds from entering. Ventilation provided under white metal powder coated roof. Proper Placement: Nest box should be placed in early spring. Mount nest box approximately 4 feet to 5 feet high on a pole or baffled wood post facing an open field .