WESTERN GREBE (Aechmophorus occidentalis)
The western grebe is RED-listed because of its few active breeding sites, and the vulnerability of those sites to habitat erosion and human disturbance. Large wintering flocks are also vulnerable to marine oil spills. Although it is a common to very abundant migrant in southern B.C., is very abundant on the south coast, and is locally common on large open lakes of the southern interior, regular breeding in the province is restricted to only three areas.
The western grebe is the largest of five grebe species that occur in B.C. It is entirely dependent on large, freshwater marshes or lakes for breeding. It breeds colonially, but because not all pairs breed at the same time, the breeding season extends from late April through late August. Most pairs nest close together, and colonies may extend over several hectares of emergent vegetation. Nests are floating platforms of marsh vegetation attached to stems of emergent plants (e.g., bulrush, cattail).
Nesting marshes must have extensive stands of emergent vegetation and stable water levels throughout the nest-building, egg-laying and incubation periods. They must also be free of human disturbance, which is implicated in the loss of at least three historic nesting areas in B.C. Power-boating can swamp nests with eggs, and close approach by canoes, swimmers or boats causes incubating birds to leave their nests and gives gulls increased opportunities to take eggs.
The western grebe occurs throughout most ecosections in the southern half of the province, but known breeding concentrations are confined to the following ecosections:
GED: FRL
CEI: (CAB-former)
SIM: SCM
SOI: NOB, NTU, (THB-former)
BG, CWH, ICH, IDF (breeding sites only)
About 200 pairs of western grebe are thought to breed in B.C., in lowland lakes between
300--650 m elevation. Regular breeding occurs only at a) Shuswap Lake at Salmon Arm, b) the north arm of Okanagan Lake, and c) lakes within the Creston Valley Wildlife Management Area (Duck Lake, Leach Lake and the south end of Kootenay Lake). There are also two recent records of single pairs breeding in the Fraser River estuary marshes. Former breeding sites include Williams Lake, Swan Lake (near Vernon) and Kamloops Lake.
This grebe occurs along the length of the coast and in the interior from the Peace River south through Babine and Stuart lakes to the U.S. border.
Wintering and migrating birds (and nonbreeding birds in summer), forage and stage along protected bays and seashores on the coast, and on large lakes in the interior. Large numbers winter off the Fraser River, in English Bay, in Boundary Bay, in the larger bays of southeastern Vancouver Island, through the Gulf Islands, and in protected sounds on the west coast of Vancouver Island. Coastal flocks may number up to 10 000 birds. In the interior, it winters in smaller numbers, mainly on large, ice-free lakes.
Critical ecosystem units for breeding include ES, LL, MR, RE.
2: herb - near the perimeter of freshwater wetlands and lakes
Extensive stands of emergent vegetation (e.g., bulrush, Scirpus sp.; cattail, Typha latifolia; reed canary grass, Phalaris arundinacea) in medium-to-large, shallow lakes are needed for nesting. Stable water levels and low levels of disturbance are critical, and nesting lakes must also contain high populations of small fish, because grebes feed near their nest sites.
Burger, A.E. 1991. Status report on Western Grebes in British Columbia. Unpubl. report
prepared for the Wildl. Br., B.C. Environ., Victoria, B.C.
Forbes, L.S. 1985. The feeding ecology of Western Grebes breeding at Duck Lake,
British Columbia. MSc thesis, Univ. Man., Winnipeg, MB.
_________. 1988. Western Grebe nesting in British Columbia. Murrelet
69:28-33.
Munro, J.A. 1941. Studies of waterfowl in British Columbia: the grebes. B.C. Prov. Mus.,
Victoria, B.C. Occas. Pap. No. 3.
Storer, R.W. and G.L. Neuchterlein. 1992. Western and Clarke's Grebe. In The Birds of
North America, No. 26. A. Poole, P. Stettenheim and F. Gill (eds.). Philadelphia: The Academy of Natural Sciences; Washington, DC: The American Ornithologists' Union.
Weber, W.C. and J. Ireland. 1992. Tidewater breeding records of the Western Grebe near
Vancouver, British Columbia. Western Birds 23:33-34.
