Population decline and the threat of extinction are realities currently facing many species. Yet, in most cases, the detailed demographic data necessary to identify causes of population decline are unavailable. Using 43 years (1975-2017) of data from a box-nesting population of tree swallows (Tachycineta bicolor), we identified reduced survival of offspring as a probable demographic cause of population decline. Poor fledging success was associated with increased predation and poor weather conditions during early nestling development. Low juvenile survival and subsequent recruitment was linked to poor weather conditions during the post-fledging period and may also be linked to conditions on the wintering grounds. Regional weather conditions during critical stages of breeding (early nestling and post-fledging) have become progressively worse over the 43-year study period. None of the other factors linked to offspring survival have similarly deteriorated. Overall, our results suggest tree swallows should be added to the growing list of species challenged by climate change, and that other species of aerial insect specialists may face similar impacts of climate change.

中文翻译：

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燕子（Tachycineta bicolor）的种群减少与气候变化和繁殖场的恶劣天气有关。

人口减少和灭绝的威胁是当前许多物种面临的现实。但是，在大多数情况下，尚无法找到确定人口减少原因的详细人口统计数据。我们使用盒燕（Tachycineta bicolor）的一箱嵌套种群中的43年（1975-2017）数据，我们确定后代的生存减少是人口减少的人口统计学原因。雏鸟发育早期，捕食成功不佳与捕食增加和天气条件差有关。青少年存活率低和随后的征募与后初时期的恶劣天气条件有关，也可能与越冬条件有关。在为期43年的研究期内，育种关键阶段（早期筑巢和出雏后）的区域天气状况逐渐恶化。与后代生存相关的其他因素均未类似地恶化。总体而言，我们的结果表明，应将燕子加入到日益受到气候变化挑战的物种清单中，而其他空中昆虫专家物种可能也面临类似的气候变化影响。