We examined how variation in MeHg concentrations through time is reflected in birds, a taxon commonly used as a biological indicator of ecosystem health. Using museum specimens collected from 1880 to 2016, we measured feather MeHg concentrations in six species of birds that breed in New York State and have distinct dietary and habitat preferences. We predicted that MeHg concentrations in feathers would mirror Hg emission patterns in New York State and increase through time until 1980 then decrease thereafter in response to increased regulation of anthropogenic Hg emissions. We found that MeHg concentrations increased with δ¹⁵N, and that MeHg feather concentrations for some individuals from four of the six species examined exceeded concentrations known to cause negative sublethal effects in birds. In contrast to our prediction, MeHg concentrations in feathers did not parallel global or local Hg emissions through time and varied by species, even after controlling for possible changes in diet and habitat. MeHg concentrations varied substantially within species and individual specimens, suggesting that high within-individual variation in feather MeHg concentrations caused by spatiotemporal variation in molt, environmental Hg exposure, or mobility decoupling Hg uptake from breeding sites, may obscure trends in MeHg through time. Our study provides a unique assessment of feather MeHg in six species not typically analyzed using this retrospective approach.

我们研究了鸟类体内MeHg浓度随时间的变化如何反映，鸟类是一种通常用作生态系统健康生物指标的分类单元。使用从1880年至2016年收集的博物馆标本，我们测量了纽约州繁殖的六种鸟类的羽毛MeHg浓度，这些鸟类具有独特的饮食和栖息地偏好。我们预测羽毛中的MeHg浓度将反映纽约州的Hg排放模式，并一直持续到1980年，然后随着人为汞排放法规的增加而下降。我们发现，甲基汞浓度的增加δ ¹⁵N，并且来自六个受检物种中四个物种的某些个体的MeHg羽毛浓度超过了已知对鸟类造成负面亚致死作用的浓度。与我们的预测相反，即使控制饮食和生境的可能变化，羽毛中的甲基汞浓度也不随时间推移而与全球或局部汞排放平行，并且随物种而变化。MeHg的浓度在物种和单个样本中的变化很大，这表明由蜕皮时空变化，环境Hg暴露或从繁殖场所吸收的Hg迁移引起的羽毛MeHg浓度的高个体内变化可能会掩盖MeHg随时间的变化趋势。我们的研究提供了对六种常见的羽毛MeHg的独特评估，这些羽毛通常不会使用这种回顾性方法进行分析。