IBA Snake Island
Nanaimo, British Columbia
Site Summary
BC055 Latitude
49.216° N
123.891° W
0 - 12 m
3.96 km²
scrub/shrub, coastal sand dunes & beaches, open sea, inlets/coastal features (marine), coastal cliffs/rocky shores (marine)
Land Use:
Not Utilized (Natural Area)
Potential or ongoing Threats:
Disturbance, Interactions with native species/disease, Oil slicks
IBA Criteria: Nationally Significant: Congregatory Species
Conservation status: IBA Conservation Plan written/being written
Restricted access for IBA coordinators
Login name: Password:


View in mobile

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.
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, Black Oystercatchers (5 pairs in 1999) and Pigeon Guillemots also nest on the island.

IBA Criteria
SpeciesT | A | I Links Date Season Number G C N
Black Oystercatcher 2014 WI 91
Iceland Gull (Thayer's) 2015 WI 150
Note: species shown in bold indicate that the maximum number exceeds at least one of the IBA thresholds (sub-regional, regional or global). The site may still not qualify for that level of IBA if the maximum number reflects an exceptional or historical occurrence.
Conservation Issues
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.

The IBA Program is an international conservation initiative coordinated by BirdLife International. The Canadian co-partners for the IBA Program are Birds Canada and Nature Canada.
   © Birds Canada