Jardine Catherine B, Bond Alexander L, Davidson Peter J A, Butler Robert W, Kuwae Tomohiro
Bird Studies Canada, Pacific Wildlife Research Centre, Delta, British Columbia, Canada.
Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
PLoS One. 2015 Apr 14;10(4):e0124164. doi: 10.1371/journal.pone.0124164. eCollection 2015.
Many shorebird species undertake long-distance migrations punctuated by brief stays at food-rich, estuarine stopover locations. Understanding use of these food resources helps guide conservation and responsible development decisions. We determined the extent and degree to which Western Sandpiper (Calidris mauri) utilized biofilm as a food resource across a large and variable stopover location during northward (spring) migration. We investigated the spatial heterogeneity in diet composition, to determine whether shorebirds were consistently feeding on biofilm or whether diet varied between naturally and anthropogenically delineated sites. We used stable isotope analysis to estimate that biofilm conservatively comprised 22% to 53% of Western Sandpiper droppings across all sampling sites and that prey composition differed significantly between areas within the stopover location. Widespread biofilm consumption demonstrates the importance of biofilm as a dietary component. Variable diet composition suggests that habitat heterogeneity may be an important component of high quality stopover locations in the context of "state-dependant trade-offs" of Western Sandpiper population sub-groups. Future management decisions must consider and address potential impacts on the biofilm community throughout a stopover location, as single site studies of diet composition may not be adequate to develop effective management strategies for entire stopover sites.
许多滨鸟物种会进行长途迁徙，期间会在食物丰富的河口中途停歇地短暂停留。了解这些食物资源的利用情况有助于指导保护和合理开发决策。我们确定了西部滨鹬（Calidris mauri）在向北（春季）迁徙期间，在一个大型且多样的中途停歇地利用生物膜作为食物资源的程度和范围。我们研究了饮食组成的空间异质性，以确定滨鸟是否持续以生物膜为食，或者饮食在自然划定和人为划定的地点之间是否存在差异。我们使用稳定同位素分析估计，在所有采样点，生物膜在西部滨鹬粪便中的保守占比为22%至53%，并且中途停歇地内不同区域的猎物组成存在显著差异。广泛食用生物膜表明生物膜作为饮食成分的重要性。饮食组成的变化表明，在西部滨鹬种群亚群的“状态依赖权衡”背景下，栖息地异质性可能是高质量中途停歇地的一个重要组成部分。未来的管理决策必须考虑并解决对整个中途停歇地生物膜群落的潜在影响，因为单一地点的饮食组成研究可能不足以制定针对整个中途停歇地的有效管理策略。
