Coveside Bluebird Bird House, Sparrow Resistant - This Kentucky style, slot entrance bluebird house is designed to thwart sparrows. According to research at the University of Kentucky, bluebirds prefer a slot entrance to the standard circular hole -- sparrows prefer the opposite. In addition, sparrows don't like a shallow box and bluebirds don't seem to mind. This box is only 5" deep but if sparrows still continue to be a problem, a wooden insert is included to reduce the depth even more. Sparrows rarely use the 3-1/2" depth, but bluebirds will still occupy it. RANGE: Breeds east of the Rockies from southeastern Canada to Gulf of Mexico. Winters in southern part of breeding range and Mexico. HABITAT: Enjoys open woodlands, fields and farmlands with scattered trees. Dimensions: 10"h x 6"w x 8-1/2"d ~Brand: Coveside ~Availability: Usually ships Within 3 Business Days