Endogenous biomarkers reveal diet partitioning among three sympatric species of swallows

Since the early 1990s, aerial insectivorous birds have shown serious population declines in North America, but it is not clear if factors common to all species within this guild account for these declines. Among sympatric swallows, population trends differ, and this may be due to differences in ecology operating throughout the annual cycle. Although these species all feed on aerial insects, prey taxa can differ tremendously in their “aeroecology” and use by swallows. We examined the potential for dietary differences among three species of swallows, Barn Swallow (Hirundo rustica), Cliff Swallow (Petrochelidon pyrrhonota), and Tree Swallow (Tachycineta bicolor), breeding sympatrically in southern Ontario, Canada. Potential interspecific differences in nestling diet were examined using two endogenous biomarkers, DNA barcoding of nestling feces and stable isotope analysis (δ 2H, δ 13C, δ 15N) of nestling feathers. We found evidence for differences in dietary sources of provisioned young whe...自20世纪90年代初以来，北美地区的空中食虫鸟类（aerial insectivorous birds）种群出现了严重的衰退趋势，但目前尚不清楚该生态类群（guild）内所有物种共有的驱动因子是否为此次种群下降的原因。在同域分布的燕科鸟类中，种群动态趋势存在显著差异，这或许是因为全年生活周期中不同物种的生态学特征存在区别。尽管这些燕类均以空中昆虫为食，但猎物类群的“空中生态学（aeroecology）”特征以及燕类对猎物的利用方式均存在极大差异。本研究针对加拿大安大略省南部同域繁殖的三种燕科鸟类——家燕（Hirundo rustica）、崖燕（Petrochelidon pyrrhonota）和树燕（Tachycineta bicolor）——的食性差异潜力展开了调查。我们通过两种内源性生物标志物（endogenous biomarkers）：雏鸟粪便的DNA条形码（DNA barcoding）分析与雏鸟羽毛的稳定同位素分析（stable isotope analysis，δ²H、δ¹³C、δ¹⁵N），检验了雏鸟食性的种间差异可能性。本研究发现了亲鸟饲喂幼鸟的食物来源存在差异的相关证据，[原文至此截断]