The Mackinaw and East Bay study areas (ca. 175 m above mean sea level) are forested tracts approximately 20 km north of Illinois State University. There are 700 nestboxes of the type depicted on the link below on the Mackinaw study area and 120 nestboxes on the nearby East Bay site (see maps below). House wrens (Troglodytes aedon) are dependent on naturally occurring cavities for nest sites. Our nestboxes provide high-quality, roomy nest sites, which the wrens prefer over natural cavities, so 90-95% of the nests built on the study area are built in the boxes. Each year a total of 600-900 nests are available for study. Click here for details on nestboxes.