A flurry of recently published studies indicates that both insects and birds have experienced wide-scale population declines in the last several decades. Curiously, whether insect and bird declines are causally linked has received little empirical attention. Here, we hypothesize that insect declines are an important factor contributing to the decline of insectivorous birds. We further suggest that insect populations essential to insectivorous birds decline whenever non-native lumber, ornamental, or invasive plant species replace native plant communities. We support our hypothesis by reviewing studies that show (1) due to host plant specialization, insect herbivores typically do poorly on non-native plants; (2) birds are often food limited; (3) populations of insectivorous bird species fluctuate with the supply of essential insect prey; (4) not all arthropod prey support bird reproduction equally well; and (5) terrestrial birds for which insects are an essential source of food have declined by 2.9 billion individuals over the last 50 years, while terrestrial birds that do not depend on insects during their life history have gained by 26.2 million individuals, a 111-fold difference. Understanding the consequences of insect declines, particularly as they affect charismatic animals like birds, may motivate land managers, homeowners, and restoration ecologists to take actions that reverse these declines by favoring the native plant species that support insect herbivores most productively.

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昆虫和食虫鸟类的减少有关系吗？

最近发表的一系列研究表明，昆虫和鸟类在过去几十年中都经历了大规模的种群下降。奇怪的是，昆虫和鸟类的衰退是否存在因果关系几乎没有受到实证研究的关注。在这里，我们假设昆虫减少是导致食虫鸟类减少的重要因素。我们进一步建议，每当非本地木材、观赏植物或入侵植物物种取代本地植物群落时，食虫鸟类所必需的昆虫种群就会减少。我们通过回顾显示（1）由于寄主植物专业化，昆虫食草动物通常对非本地植物表现不佳的研究来支持我们的假设；(2) 鸟类往往食物有限；(3) 食虫鸟类的种群数量随着必需昆虫猎物的供应而波动；(4) 并非所有节肢动物的猎物都能同样良好地支持鸟类繁殖；(5) 以昆虫为主要食物来源的陆鸟在过去 50 年中减少了 29 亿只，而在其生活史中不依赖昆虫的陆鸟则增加了 2620 万只，即 111-折差。了解昆虫衰退的后果，特别是它们影响到像鸟类这样有魅力的动物时，可能会激励土地管理者、房主和恢复生态学家采取行动，通过支持最能支持昆虫食草动物的本地植物物种来扭转这些衰退。而在其生命史中不依赖昆虫的陆生鸟类增加了 2620 万只，相差 111 倍。了解昆虫衰退的后果，特别是它们影响到像鸟类这样有魅力的动物时，可能会激励土地管理者、房主和恢复生态学家采取行动，通过支持最能支持昆虫食草动物的本地植物物种来扭转这些衰退。而在其生命史中不依赖昆虫的陆生鸟类增加了 2620 万只，相差 111 倍。了解昆虫衰退的后果，特别是它们影响到像鸟类这样有魅力的动物时，可能会激励土地管理者、房主和恢复生态学家采取行动，通过支持最能支持昆虫食草动物的本地植物物种来扭转这些衰退。