Since l982, the Department has overseen monitoring of these rare waterbirds. The common tern (Sterna hirundo) is classified as threatened. This species nests in Lake of the Woods County, Leech Lake, Mille Lacs Lake, and Lake Superior in the Duluth Harbor. Program emphasis includes monitoring nest productivity, nest protection measures, and habitat improvement. In l999, there were five nesting colony sites for the common tern, and a statewide population of fewer than 900 nesting pairs.