The Cousins are located approximately 16 km southeast of Blind River near the centre of Lake Huron's North Channel. They consist of two small islands (West and East Cousins), which are located about 250 m apart. Cape Roberts, on Manitoulin Island is located about 10 km to the south, and numerous rocky islands and shoals are located about six to ten km to the north. The islands are comprised of limestone and cobble, with moderate tree and shrub growth.
During a survey completed in 1991, 467 Caspian Tern nests were recorded on The Cousins. This represented nearly 1.5% of the estimated North American Caspian Tern population and almost 5% of the Great Lakes estimated population at that time. In 1998, however, only 130 nests were recorded, a number that is still of national significance. Large numbers of Caspian Terns have occurred at The Cousins for several decades; a survey in 1980 recorded 395 Caspian Tern nests. In the late 1970s, Caspian Terns were designated by COSEWIC as a nationally vulnerable species, but they were delisted in 1999.
Other colonial waterbirds nesting on the island include: Ring-billed Gull (853 nests in 1989), and Double- crested Cormorant (114 nests in 1989, and 587 nests in 1997). During the 1980 survey, 99 Herring Gull nests were also recorded, but this species was absent in 1989.
BirdLife International (2021) Important Bird Areas factsheet: The Cousins. Downloaded from http://www.birdlife.org on 06/12/2021.