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Characteristics and Range The Western Grebe is Manitoba's largest grebe, measuring 60 cm including a long thin neck. The blackish gray upperparts and contrasting white underparts, with red eyes surrounded by black, make this species one of the most distinctive of the grebe family. The species' courtship displays, with pairs facing one another, bowing, diving for vegetation, and running across the water in parallel, are spectacular. The breeding range extends from Manitoba west to British Columbia and south to northeastern California and northern New Mexico. The wintering range extends along the Pacific coast from the Alaskan Panhandle to Baja California and in the western Mexican interior south to Mexico City (La Porte et al. 2013).

Distribution, Abundance, and Habitat Western Grebes were found in the larger lakes of the Prairie Potholes and Boreal Taiga Plains, with records in just three squares of the Boreal Hardwood Transition (possibly involving overshooting migrants or non-breeders). During the atlas period, large colonies were noted around Delta Marsh (e.g., 1,428 nests in eight colonies in 2010, La Porte 2012), Whitewater Lake (where high counts have included 4,098 on 6 August, 2017, Manitoba Important Bird Area Program), Netley-Libau Marsh, and the Shoal Lakes, with smaller numbers found at sites such as Pelican Lake (where increased boat traffic and loss of reed beds has apparently led to a reduction in nesting grebes). The northernmost confirmed breeding was at Dawson Bay on Lake Winnipegosis, corresponding closely to the range depicted in The Birds of Manitoba. The Western Grebe nests colonially, typically on large water bodies with emergent vegetation. Much of our knowledge of nesting habitat comes from research at Delta Marsh where the species' preferred nesting substrate is emergent bulrushes, Phragmites, cattails, with dense submergent vegetation occasionally used, over a minimum water depth of 25 cm (Nuechterlein 1975, La Porte 2012, La Porte et al. 2013).

Trends, Conservation, and Recommendations Western Grebes are not globally threatened; however, there is some evidence of range-wide decline, albeit difficult to quantify, from sources such as the CBC and other counts (La Porte et al. 2013). Although wind storms and wave action, as well as gull predation, take their toll on nesting colonies, this species is perhaps especially vulnerable to human-caused mortality from boating, oil spills, and entanglement in fishing line, nets, and other equipment, and may suffer effects of mercury contamination and pollution (The Birds of Manitoba, La Porte et al. 2013). At Delta Marsh, the increasing prevalence of hybrid cattail, otter predation, and nest destruction by spawning carp are also factors (La Porte 2012); however, the recent carp-exclusion program (Manitoba Sustainable Development 2015) may already be bringing a positive impact.

Lorelie Mitchell, Christian Artuso

Recommended citation: Mitchell, L., and C. Artuso. 2018. Western Grebe in Artuso, C., A. R. Couturier, K. D. De Smet, R. F. Koes, D. Lepage, J. McCracken, R. D. Mooi, and P. Taylor (eds.). The Atlas of the Breeding Birds of Manitoba, 2010-2014. Bird Studies Canada. Winnipeg, Manitoba http://www.birdatlas.mb.ca/accounts/speciesaccount.jsp?sp=WEGR&lang=en [11 Oct 2024]