High temperatures and low rainfall consistently constrain reproduction in arid-zone bird species. Understanding the mechanisms underlying this pattern is critical for predicting how climate change will influence population persistence and to inform conservation and management. In this study, we analyzed Southern Pied Babbler Turdoides bicolor nestling survival, daily growth rate and adult investment behavior during the nestling period over three austral summer breeding seasons. High temperatures were associated with lower body mass, shorter tarsi, and reduced daily growth rates of nestlings. Our piecewise structural equation models suggested that direct impacts of temperature had the strongest influence on nestling size and daily growth rates for both 5-day-old and 11-day-old nestlings, followed by temperature-related adjustments to provisioning rates by adults. Rainfall and group size influenced the behavior of provisioning adults but did not influence nestling growth or survival. Adjustments to adult provisioning strategies did not compensate for direct negative effects of high air temperatures on nestling size or daily growth rates. Detailed mechanistic data like these allow us to model the pathways by which high temperature causes nest failure. In turn, this could allow us to design targeted conservation action to effectively mitigate climate effects.

中文翻译：

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高温对合作繁殖鸟类羽化的直接和间接影响

高温和低降雨量一直限制着干旱区鸟类的繁殖。了解这种模式背后的机制对于预测气候变化将如何影响人口持久性并为保护和管理提供信息至关重要。在这项研究中，我们分析了南方斑鹛鹛双色雏鸟在三个南方夏季繁殖季节的雏鸟期间的存活率、日增长率和成虫投资行为。高温与较低的体重、较短的跗骨和降低雏鸟的每日生长率有关。我们的分段结构方程模型表明，温度的直接影响对 5 日龄和 11 日龄雏鸟的雏鸟大小和日生长率的影响最大，其次是与温度相关的成年人供给率的调整。降雨量和群体规模影响了供应成年人的行为，但不影响雏鸟的生长或生存。对成虫供应策略的调整并不能弥补高温对雏鸟大小或每日生长率的直接负面影响。像这些详细的机械数据使我们能够模拟高温导致巢失败的途径。反过来，这可以让我们设计有针对性的保护行动，以有效减轻气候影响。对成虫供应策略的调整并不能弥补高温对雏鸟大小或每日生长率的直接负面影响。像这些详细的机械数据使我们能够模拟高温导致巢失败的途径。反过来，这可以让我们设计有针对性的保护行动，以有效减轻气候影响。对成虫供应策略的调整并不能弥补高温对雏鸟大小或每日生长率的直接负面影响。像这些详细的机械数据使我们能够模拟高温导致巢失败的途径。反过来，这可以让我们设计有针对性的保护行动，以有效减轻气候影响。