Lambert Channel is the body of water that separates Denman and Hornby Islands. These islands are located off the east coast of Vancouver Island in the central part of the Strait of Georgia. Within Lambert Channel, the region with large numbers of seaducks extends several kilometres along the entire northern shore of Denman Island (including the Seal Islets), and the northwestern, western, eastern and southern shores of Hornby Island. The shores of the channel are a mixture of gravel and rock, with the water currents in the channel being influenced by tides twice daily. The upland habitats adjacent to the channel are part of the dry Garry Oak/Douglas fir forests that are restricted in British Columbia to the Strait of Georgia. Hornby Island is forested with Douglas fir on the southeast peninsula, and has mostly rocky shores, culminating in a large rocky headland (St. Johns Point) at the tip of this peninsula. The waters within 2 km of the shores of Hornby Island are included in the IBA.
Birds concentrate in the Lambert Channel to take advantage of spawning herring, which are usually present during the first few weeks of March. During detailed field surveys in 1989 and 1990, at least three species were recorded in globally significant numbers: Pelagic Cormorants (up to 2% of the estimated North American north Pacific population); Surf/White-winged scoters (1 to 2% of their estimated, combined North American populations); and Glaucous-winged Gull (about 8% of the estimated north Pacific population). Nationally significant numbers of Bald Eagles are also present, with a one-day peak of 692 in 1990. In addition to these species, relatively large one-day peak numbers of Oldsquaw (8,500), Bufflehead (600), Barrows and Common goldeneye (1,400), and Common Merganser (440) were also recorded.
Lambert Channel and the waters off of Hornby Island support significant concentrations of Harlequin Duck in more than one season. During the 1989/1990 study, a peak one-day count of 600 Harlequin Ducks was recorded, and in March 1998, 2,500 were counted. During the fall of 1995, however, a even larger flock of approximately 4,000 Harlequins was observed (as much as 2.6% of the estimated western North America population) and some have reported flocks with as many as 5,000 birds. During summer and early fall, the shores of Hornby Island are also a major roost site for moulting Harlequin Ducks.
Pelagic Cormorants nest on St. Johns Point, Hornby Island, where 101 pairs were recorded in 1991 (1% of Canadian population). Glaucous-winged Gulls and Pigeon Guillemots also nest here.
BirdLife International (2020) Important Bird Areas factsheet: Lambert Channel/Hornby Island Waters. Downloaded from http://www.birdlife.org on 28/11/2020.