Mercury (Hg) is a toxic heavy metal that, when methylated to form methylmercury (MeHg), bioaccumulates in exposed animals and biomagnifies through food webs. The purpose of this study was to assess Hg concentrations in raptors migrating through the upper midwestern USA. From 2009 to 2012, 966 raptors of 11 species were captured at Hawk Ridge, Duluth, Minnesota, USA. Breast feathers were sampled to determine the concentration of total Hg. Mean Hg concentrations ranged from 0.11 to 3.46 μg g⁻¹ fresh weight across species and were generally higher in raptors that feed on birds in comparison with those that feed on mammals. To evaluate the effect of dietary sources on Hg biomagnification, carbon and nitrogen stable isotope ratios were measured in feathers of the 2 species with the highest Hg concentrations, Merlin (Falco columbarius) and Sharp-shinned Hawk (Accipiter striatus). Measured δ ¹³C values were similar in both species and indicated a primarily terrestrial-derived diet, whereas δ ¹⁵N values suggested that individual Merlin and Sharp-shinned Hawk feeding at higher trophic levels accumulated higher concentrations of Hg. The risk to birds associated with measured levels of feather Hg was evaluated by calculating blood-equivalent values using an established algorithm. Predicted blood values were then compared to heuristic risk categories synthesized across avian orders. This analysis suggested that while some Merlin and Sharp-shinned Hawk were at moderate risk to adverse effects of MeHg, most of the sampled birds were at negligible or low risk.

中文翻译：

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羽毛的汞随着营养水平的提高而增加，这两种迁徙的猛禽，即梅林（Falco columbarius）和锋利的鹰（Accipiter striatus）

汞（Hg）是一种有毒的重金属，当被甲基化形成甲基汞（MeHg）时，会在暴露的动物体内生物蓄积并通过食物网进行生物放大。这项研究的目的是评估在美国中西部上迁的猛禽中的汞含量。从2009年到2012年，在美国明尼苏达州德卢斯的霍克里奇捕获了11个物种的966个猛禽。对胸羽取样以测定总汞的浓度。平均汞浓度范围为0.11至3.46μgg ^-1整个物种的体重较重，以鸟类为食的猛禽通常比以哺乳动物为食的猛禽更高。为了评估饮食来源对汞生物放大倍数的影响，在汞含量最高的两个物种的羽毛中，分别测定了碳和氮的稳定同位素比，其中梅林（Falco columbarius）和尖锐的鹰（Accipiter striatus）。测量δ  ^13个C值分别为在这两个物种类似，并表示一个主要地面衍生的饮食，而δ  ¹⁵N值表明，在较高营养水平下饲喂的个别Merlin和Sharp-shind Hawk积累的Hg浓度较高。通过使用既定算法计算血液当量值来评估与测得的羽毛汞水平相关的禽类风险。然后将预测的血液值与跨鸟类订单综合的启发式风险类别进行比较。该分析表明，尽管一些梅林和尖锐的霍克对甲基汞的不良反应处于中等风险，但大多数采样鸟类的风险可忽略不计或低。