Snake Island

Year of compilation: 2001

Site description
Snake Island is located in the Strait of Georgia about three kilometres off the northwest point of Gabriola Island, along the east coast of Vancouver Island, British Columbia. Snake Island, which lies in the approach to Nanaimo Harbour is long and narrow and composed of sandstone. Offshore ribs of rock on either side of the main island are connected by tidal beach and rock shelf. The western side is cliffbound while the eastern side is a steep slope down to the waters edge. The flat top of the island is covered in a dense growth of grass with patches of shrubs such as rose. The area includes the marine waters in a one-kilometre radius around the island. Harbour Seals use the island as a haulout and for breeding.

Key biodiversity
Two colonial nesting birds breed on Snake Island at nationally significant levels. Surveys conducted in 1986 and 1987 recorded 673 pairs (over 2% of the national population) of Glaucous-winged Gulls and 74 pairs (about 1% of the Canadian component of the north Pacific population) of Pelagic Cormorants. Previous and additional surveys since 1987 indicate that nesting populations of these species have fluctuated. A survey early in the 1999 breeding season recorded only 204 Glaucous-winged Gulls and 16 pairs of Pelagic Cormorants.

Although not present in significant numbers, American Black Oystercatchers (5 pairs in 1999) and Pigeon Guillemots also nest on the island.

Conservation responses/actions for key biodiversity
The breeding birds of Snake Island are susceptible to disturbance, and their proximity to Nanaimo has led to some disturbance from boaters who land to picnic and party on the island. Disturbance can also occur from high-speed boats or boaters approaching the colony too closely. Snake Island lies along the ferry route between Nanaimo and Vancouver and, as in all areas along the coast, oil pollution is a potential threat. There is some indication that numbers of breeding cormorants as well as gulls may have declined, possibly as a result of disturbance by Bald Eagles. Eagles may cause cormorants to temporarily abandon their nests, which leaves them vulnerable to increased predation by gulls and corvids.

Recommended citation
BirdLife International (2022) Important Bird Areas factsheet: Snake Island. Downloaded from on 26/11/2022.