Pesticide use is pervasive and the exposure of non-target wildlife has been well documented over the past half-century. Among pesticides, anticoagulant rodenticides (AR) have emerged as a particularly important threat in forests of the western United States, with exposure and mortality reported for several species of conservation concern. To further quantify this threat, we collected specimens of Barred Owls (Strix varia) and Barred Owl x Spotted Owl hybrids from the Klamath and Cascade Mountains and Sierra Nevada in California, USA to use as indicator species for environmental contamination with AR and to infer exposure of closely related and ecologically similar Northern and California Spotted Owls (S. occidentalis caurina, and S. o. occidentalis, respectively). We tested 115 Barred Owl and 12 Barred Owl x Spotted Owl hybrid livers for 8 AR compounds and found high rates of exposure (62%) across our study area, and greater than previous studies in the Pacific Northwest. In addition, we sampled 7 ovaries from 7 females and 100% tested positive for AR. Female Barred Owls were more likely than males to be exposed (78% and 50%, respectively). Unlike previous studies, we found no clear link between illegal cannabis cultivation and AR exposure. However, Barred Owls sampled in proximity to the wildland–urban interface (WUI) were more likely to be exposed to AR. Though the exact source (e.g., cannabis cultivation or application around human dwellings) and location are unknown, the association of AR exposure with the WUI was supported from GPS data from Barred Owls, Northern and California Spotted Owls, and hybrids using the WUI for foraging. The high rate of AR exposure in Barred Owls and hybrids provides mounting evidence of an additional stressor that ARs may pose to Spotted Owls—including the first evidence for California Spotted Owls—and fauna native to western forest ecosystems.

中文翻译：

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加利福尼亚条纹猫头鹰抗凝灭鼠剂的高暴露率与荒地-城市界面有关

农药的使用无处不在，在过去的半个世纪中，非目标野生动物的暴露已得到充分记录。在杀虫剂中，抗凝血灭鼠剂 (AR) 已成为美国西部森林中的一个特别重要的威胁，据报道有几种保护问题的暴露和死亡率。为了进一步量化这种威胁，我们从美国加利福尼亚州的克拉马斯和喀斯喀特山脉以及内华达山脉收集了条纹猫头鹰 (Strix varia) 和条纹猫头鹰 x 斑点猫头鹰杂交种的标本，用作 AR 环境污染的指示物种并推断暴露情况密切相关且生态相似的北部和加利福尼亚斑点猫头鹰（分别为 S. occidentalis caurina 和 S. o. occidentalis）。我们测试了 115 只条纹猫头鹰和 12 只条纹猫头鹰 x 斑点猫头鹰杂交肝脏中的 8 种 AR 化合物，发现在我们的研究区域内的暴露率很高 (62%)，并且高于之前在太平洋西北部的研究。此外，我们从 7 名女性中抽取了 7 个卵巢样本，并且 100% 检测出 AR 阳性。雌性条纹猫头鹰比雄性更容易暴露（分别为 78% 和 50%）。与之前的研究不同，我们发现非法大麻种植与 AR 暴露之间没有明确的联系。然而，在荒地-城市界面 (WUI) 附近采样的条纹猫头鹰更有可能接触到 AR。虽然确切的来源（例如，大麻种植或在人类住宅周围的应用）和位置未知，但 AR 暴露与 WUI 的关联得到了来自 Barred Owls、Northern 和 California Spotted Owls 的 GPS 数据的支持，和使用 WUI 觅食的杂种。Barred Owls 和杂种中 AR 的高暴露率提供了越来越多的证据，证明 AR 可能对 Spotted Owls 构成额外的压力源——包括加州 Spotted Owls 的第一个证据——以及西部森林生态系统原生的动物群。