Description: Slotted entrance Bluebird house. Constructed of untreated Western Red Cedar. Built to last, this house will last several years without any additional treatment. House is designed to thwart sparrows. According to researchers, 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. Front opens for easy clean out.