Environment and Climate Change Canada’s Canadian Wildlife Service and the U.S. Fish and Wildlife Service conducted four decadal censuses (1976-1980, 1989-1990, 1997-2000, 2007-2009) of colonial waterbirds nesting across the North American Great Lakes and their associated waterways. Target species include ground-nesting birds (e.g., gulls, cormorants, pelicans, and terns) as well as tree-nesting birds (e.g., cormorants, herons, night-herons, and egrets).
Nest sites on the shoreline (and up to 1 km inland) and offshore islands (the main breeding sites) were surveyed from the Canada/U.S. border at the west end of Lake Superior near Pigeon Point, Minnesota to Cornwall, Ontario/Massena, and New York in the upper St. Lawrence River. Nest counts were completed in most years between mid-April and mid-June with the lower Great Lakes (Ontario and Erie), censused before the more northerly Great Lakes. Population trend data (based on nest counts) from all four censuses were calculated for all target species.
For additional information on individual waterbird species nesting on all the Great Lakes, please see Weseloh et al. (2002), Morris et al. (2003, 2010, 2011, 2012), Cotter et al. (2010) and Rush et al. (2015). For additional information on all colonial waterbird species nesting on individual Great Lakes, please see Weseloh et al. (2003), Hebert et al. (2008) and Morris et al. (2009).