Digges Sound is located near the northern tip of the Ungava Peninsula (northeastern Hudson Bay) between Digges Islands and Cape Wolstenhome. The Sound is lined by granite cliffs that range in height up to nearly 200 m on East Digges Island and to a height of over 300 m along the mainland. In all, there are approximately 4 km of cliffs on East Digges Island and nearly 8 km of cliffs along the Quebec shoreline. The rock is mostly granitic schist, which fractures, forming stacks and ledges.
Digges Sound is significant for the large numbers of Thick-billed Murres that nest on its cliffs. Colonies are located at both East Digges Island and Cape Wolstenhome. In 1980, the size of the East Digges colony was estimated to be about 180,000 breeding pairs; the Cape Wolstenhome colony was estimated to be somewhat smaller at about 107,000 breeding pairs. The East Digges colonies were revisited in 1990 and again in 1992; there was no evidence of a marked change in population. The total number of Thick-billed Murres nesting along Digges Sound is roughly 287,000 breeding pairs. This represents approximately 2.6% of the global, 4.4% of the North Atlantic, and almost 20% of the eastern Canada Thick-billed Murre population.
In addition to Thick-billed Murres, approximately 860 pairs of Black Guillemots nest on islands in Digges Sound. Approximately 350 pairs of Iceland Gulls (Kumlien's form) are also present in the area. A small number of Atlantic Puffins nest in a colony on Dome Island to the south of West Digges Island.
BirdLife International (2020) Important Bird Areas factsheet: Digges Sound. Downloaded from http://www.birdlife.org on 29/11/2020.