Abstract Species are declining worldwide, but while some are becoming threatened, few others thrive under novel environmental conditions. Land use changes and biological invasion are the main drivers of this ‘biotic homogenization’ (BH) that increasingly occurs in human-dominated landscapes. Among birds, several groups of species have been identified as ‘winners’ in this process (e.g. invasive and native urban specialists and generalist species). Yet, as populations continue to grow, competition can appear between those groups and it is not yet clear who are the primary ‘winners’ in the BH process. Here, we analyze trends of common native and non-native birds during the last 15 years across Israel, where large populations of very destructive invasive alien bird species were introduced towards the end of the previous century, using a nation-wide citizen-science program, and two local standardized surveys. Community and population analyses showed that the non-native species are the primary ‘winners’ of the BH process. Native urban specialists and generalist species that were previously considered as ‘winners’ are now among the ‘losers’. For instance, populations of the invasive common myna increased dramatically, while populations of the previously widespread house sparrow strongly decreased. Previous studies conducted in Israel have shed light on the mechanisms through which invasive bird species can impact native species, notably competition. We show that these processes are among the key factors that drive population declines and changes in bird communities. This highlights the importance of acting now, especially since non-native species are currently spreading from human-dominated areas to more natural environments.

中文翻译：

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当赢家是输家时：外来入侵鸟类在生物同质化过程中胜过本土赢家

摘要 世界范围内的物种正在减少，虽然有些物种受到威胁，但很少有人在新的环境条件下茁壮成长。土地利用变化和生物入侵是这种“生物同质化”（BH）的主要驱动因素，这种现象越来越多地发生在人类主导的景观中。在鸟类中，有几组物种在这个过程中被确定为“赢家”（例如入侵和本地城市专家和通才物种）。然而，随着人口的持续增长，这些群体之间可能会出现竞争，目前尚不清楚谁是 BH 过程中的主要“赢家”。在这里，我们分析了过去 15 年来以色列常见本地和非本地鸟类的趋势，在上世纪末引入了大量极具破坏性的外来入侵鸟类物种，使用全国公民科学计划和两个地方标准化调查。社区和种群分析表明，非本地物种是 BH 过程的主要“赢家”。以前被认为是“赢家”的本地城市专家和通才物种现在是“输家”。例如，入侵的八哥的数量急剧增加，而以前广泛分布的家麻雀的数量急剧减少。之前在以色列进行的研究揭示了入侵鸟类影响本地物种的机制，尤其是竞争。我们表明，这些过程是推动鸟类群落数量下降和变化的关键因素之一。这凸显了现在行动的重要性，