Non-native, invasive plants can impact birds by altering food sources, nesting substrates and other critical resources. Japanese barberry (Berberis thunbergii) is one of the most invasive, non-native woody plants in in the northeastern USA, and yet almost nothing is known about its effects on birds or other wildlife. To investigate individual-level impacts of Japanese barberry on a forest-breeding bird, we compared food abundance (leaf-litter arthropod biomass) and the physiological condition of territorial male ovenbirds (Seiurus aurocapilla) between areas of a forest preserve in New York State that had high or low densities of Japanese barberry. We used haemoglobin and plasma triglyceride concentrations to indicate energetic condition, plasma uric acid and total plasma protein levels to indicate diet quality, and heterophil to lymphocyte ratios to indicate chronic stress. We found no difference in arthropod biomass between ovenbird territories that were heavily invaded by or relatively free of Japanese barberry. Perhaps largely as a result, we found no relationship between Japanese barberry density and any of our five haematological condition indices. There was also no difference in body mass, body size or age ratio between ovenbirds nesting in areas with low or high densities of Japanese barberry to suggest that relatively uninvaded forest patches were in greater demand and acquired by the most dominant individuals. Our results indicate that Japanese barberry does not reduce habitat quality for breeding male ovenbirds in a way that affects their prey abundance or physiological condition, but we caution that other species of birds and other aspects of habitat quality could be affected differently. We encourage future research on additional bird species and the effects of Japanese barberry on factors such as diet composition, pairing and nesting success and post-fledging survival to improve science-based decision-making about the extent to which conservation resources should be applied towards Japanese barberry control.

中文翻译：

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在日本本土伏牛花（Berberis thunbergii）入侵的森林中，迁徙鸣禽繁殖的栖息地质量的生理指标。

非本地入侵植物会通过改变食物来源，筑巢基质和其他关键资源来影响鸟类。日本伏牛（Berberis thunbergii）是美国东北部最具入侵性，非本土的木本植物之一，但对其对鸟类或其他野生生物的影响几乎一无所知。为了研究日本伏牛对森林繁殖鸟类的个体影响，我们比较了纽约州森林保护区之间的食物丰度（凋落的节肢动物生物量）和领土雄性火鸟（Seiurus aurocapilla）的生理状况，高或低密度的日本伏牛花。我们使用血红蛋白和血浆甘油三酸酯浓度来表示能量状况，血浆尿酸和血浆总蛋白水平来表示饮食质量，以及嗜异性细胞与淋巴细胞的比率表示慢性应激。我们发现在被严重伏击或相对不含日本伏牛花的火鸟鸟地区之间，节肢动物的生物量没有差异。也许很大程度上是由于结果，我们发现日本伏牛花密度与我们的五个血液学疾病状况指数之间没有任何关系。在伏牛密度低或高的地区筑巢的鸟鸟的体重，体型或年龄比也没有差异，这表明相对未入侵的森林斑块需求量更大，并且由最主要的个体获得。我们的结果表明，日本伏牛花不会以影响猎物丰富度或生理状况的方式降低繁殖雄性火鸟的栖息地质量，但是我们提醒您，其他鸟类和栖息地质量的其他方面也会受到不同的影响。我们鼓励将来对其他鸟类物种以及日本伏牛diet对饮食组成，配对和筑巢成功以及成活后存活等因素的影响进行研究，以改进基于科学的决策，确定应将保护性资源应用于日本人的程度伏牛花控制。