Knutson, Melinda G., Greg Butcher, Jane Fitzgerald, and Julie Shieldcastle. 2001. Partners in Flight Bird Conservation Plan for The Upper Great Lakes Plain (Physiographic Area 16). La Crosse, WI: U.S. Geological Survey, Upper Midwest Environmental Sciences Center in cooperation with Partners in Flight. https://www.partnersinflight.org/wp-content/uploads/2017/02/PA-16-Upper-Great-Lakes.pdf