Birds of Indian Subcontinent

Temporal Variation in Microhabitat Relationships among Grebes and Coots

Publication Type:Journal Article
Year of Publication:1990
Authors:Barnes, GG, Nudds, TD
Journal:The Wilson Bulletin
Date Published:1990
ISBN Number:00435643
Keywords:Fulica, Fulica americana, Fulica atra, Podiceps, Podiceps auritus, Podicipedidae, Podilymbus, Podilymbus podiceps, Rallidae
Abstract:Interspecific competition may shape species' niches such that relative niche positions remain consistent in niche space. However, during times when competition is relaxed, it has been hypothesized that significant rearrangement of species' niches occurs, both relative to each other and to available niche space. We compared microhabitat niche relationships among coexisting Horned Grebes (Podiceps auritus), Pied-billed Grebes (Podilymbus podiceps), and American Coots (Fulica americana) in aspen parkland near Minnedosa, Manitoba, from 1982 to 1984. Despite annual variation in the structure and abundance of microhabitats due to fluctuating water levels, niche relationships among grebes and coots remained relatively consistent. Coots generally occupied shallow sites with tall vegetation, and Horned Grebes used deep sites with little vegetation; both species used sites with little spatial complexity. Pied-billed Grebes occupied sites intermediate to those of the other species with respect to water depth and vegetation height, and used more spatially heterogeneous sites. In two low water years, overall niche separation was greatest along a depth-vegetation height dimension. In a high water year, niche separation was greatest along a spatial complexity dimension. Nevertheless, relative amounts of niche separation remained consistent; coots and Horned Grebes were always most different, and coots and Pied-billed Grebes were always most similar, in microhabitat use. These data support the idea that niche organization in this guild results from interspecific interactions rather than random processes.
Short Title:The Wilson Bulletin
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