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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Pleistocene to historic shifts in bald eagle diets on the Channel Islands, California
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Pleistocene to historic shifts in bald eagle diets on the Channel Islands, California

机译：更新世至加利福尼亚海峡群岛秃鹰饮食的历史性转变

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Studies of current interactions among species, their prey, and environmental factors are essential for mitigating immediate threats to population viability, but the true range of behavioral and ecological flexibility can be determined only through research on deeper time-scales. Ecological data spanning centuries to millennia provide important contextual information for long-term management strategies, especially for species that now are living in relict populations. Here we use a variety of methods to reconstruct bald eagle diets and local abundance of their potential prey on the Channel Islands from the late Pleistocene to the time when the last breeding pairs disappeared from the islands in the mid-20th century. Faunal and isotopic analysis of bald eagles shows that seabirds were important prey for immature/adult eagles for millennia before the eagles' local extirpation. In historic times (A.D. 1850-1950), however, isotopic and faunal data show that breeding bald eagles provisioned their chicks with introduced ungulates (e.g., sheep), which were locally present in high densities. Today, bald eagles are the focus of an extensive conservation program designed to restore a stable breeding population to the Channel Islands, but native and nonnative prey sources that were important for bald eagles in the past are either diminished (e.g., seabirds) or have been eradicated (e.g., introduced ungulates). In the absence of sufficient resources, a growing bald eagle population on the Channel Islands could expand its prey base to include carrion from local pinniped colonies, exert predation pressure on a recovering seabird population, and possibly prey on endangered island foxes.
机译：对物种，它们的猎物和环境因素之间当前相互作用的研究对于减轻对种群生存力的直接威胁至关重要，但是行为和生态灵活性的真实范围只能通过更深的时间尺度研究来确定。跨世纪到几千年的生态数据为长期管理策略提供了重要的背景信息，尤其是对于现在生活在遗留种群中的物种而言。在这里，我们使用各种方法来重建白头鹰的饮食，并从晚更新世到20世纪中叶最后一批繁殖对从这些岛上消失之时，在海峡群岛上重建其潜在猎物的局部丰富性。对白头鹰的动物和同位素分析表明，在老鹰局部灭绝之前的几千年中，海鸟是不成熟/成年老鹰的重要猎物。然而，在历史时期（公元1850-1950年），同位素和动物区系数据显示，繁殖的白头鹰为其雏鸡提供了引入的有蹄类动物（例如绵羊），它们在当地高密度存在。如今，秃鹰是旨在恢复海峡群岛稳定种群繁殖的广泛保护计划的重点，但过去对秃鹰重要的本地和外来猎物来源已减少（例如，海鸟）或已经根除（例如引入的有蹄类动物）。在缺乏足够资源的情况下，海峡群岛上不断增长的白头鹰种群可能会扩大其捕食基础，以包括本地钉扎殖民地的腐肉，对正在恢复的海鸟种群施加捕食压力，并可能对濒临灭绝的海岛狐狸施加猎物压力。

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