We analyse late summer phenology, abundance, and diversity of waders and waterfowl on a small gravel island, Kosa, on the western shore of Lake Baikal, eastern Siberia. We expected that the assemblages of waterbirds at such a small-scale, low quality roosting site would be characterised by lower species-diversity and numbers compared with high-quality staging sites like coastal mudflats. In comparison with such sites, however, Kosa Island hosted a surprisingly diverse wader assemblage. Abundance, in contrast, was as expected very low, and rather equally distributed across species. Consequently, Shannon diversity indices and the evenness of species abundance were high compared to high quality staging sites like the German Wadden Sea. We speculate that the combination of high diversity and high evenness indices may generally characterise low quality staging sites that are visited by a wide array of species in an opportunistic fashion. However, comparative analyses of a larger sample of sites are needed to test this prediction.