Lead (Pb) exposure is a widespread wildlife conservation threat. Although commonly associated with Pb-based ammunition from big-game hunting, small mammals (e.g., ground squirrels) shot for recreational or pest-management purposes represent a potentially important Pb vector in agricultural regions. We measured the responses of avian scavengers to pest-shooting events and examined their Pb exposure through consumption of shot mammals. There were 3.4-fold more avian scavengers at shooting fields relative to those at fields with no recent shooting, and avian scavengers spent 1.8-fold more time feeding after recent shooting events. We isotopically labeled shot ground squirrels in the field with an enriched ¹⁵N isotope tracer; 6% of avian scavengers sampled within a 39 km radius reflected this tracer in their blood. However, 33% of the avian scavengers within the average foraging dispersal distance of nests (0.6–3.7 km) were labeled, demonstrating the importance of these shooting fields as a source of food for birds nesting in close proximity. Additionally, Pb concentrations in 48% of avian scavengers exceeded subclinical poisoning benchmarks for sensitive species (0.03–0.20 μg/g w/w), and those birds exhibited reduced δ-aminolevulinic acid dehydratase activity, indicating a biochemical effect of Pb. The use of shooting to manage small mammal pests is a common practice globally. Efforts that can reduce the use of Pb-based ammunition may lessen the negative physiological effects of Pb exposure on avian scavengers.

中文翻译：

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小型哺乳动物射击作为鸟类清道夫铅暴露的管道

铅 (Pb) 暴露是一种广泛的野生动物保护威胁。虽然通常与来自大型游戏狩猎的铅基弹药有关，但出于娱乐或害虫管理目的而射杀的小型哺乳动物（例如地松鼠）代表了农业地区潜在的重要铅载体。我们测量了鸟类清道夫对害虫射杀事件的反应，并通过食用射杀的哺乳动物检查了它们的铅暴露情况。与最近没有射击的田地相比，射击场的鸟类清道夫多出 3.4 倍，最近射击事件后鸟类清道夫的觅食时间增加了 1.8 倍。我们用富含¹⁵N同位素示踪剂；在 39 公里半径范围内采样的鸟类清道夫中有 6% 在其血液中反映了这种示踪剂。然而，在巢穴的平均觅食分散距离（0.6-3.7 公里）内，有 33% 的鸟类清道夫被标记，表明这些射击场作为近​​距离筑巢的鸟类的食物来源的重要性。此外，48% 的鸟类清道夫的铅浓度超过了敏感物种的亚临床中毒基准（0.03-0.20 μg/gw/w），这些鸟类的 δ-氨基乙酰丙酸脱水酶活性降低，表明铅的生化作用。使用射击来管理小型哺乳动物害虫是全球的普遍做法。减少使用铅基弹药的努力可能会减轻铅暴露对鸟类清道夫的负面生理影响。