Climate change and associated changes in weather patterns have globally widespread effects on natural systems. Shifts in phenology can affect the reproductive success of birds by causing a mismatch between the onset of breeding and favourable conditions for reproduction, such as a peak in food availability. Weather conditions and their changes have also long been discussed as affecting the reproductive success of grouse (Tetraoninae) and contributing to rapid declines in many central European populations. We monitored the reproductive success of Western Capercaillie Tetrao urogallus in the Black Forest, Germany, over a 14-year period to study how weather conditions correlated to reproductive success and to assess whether changing environmental conditions were related to a seasonal shift in reproduction. We observed a temporal shift in peak lekking activity from late to mid-April, which corresponds to an advance of 0.65 days/year. Furthermore, we show that warm conditions during the reproductive season were positively associated with reproductive success (i.e. larger brood size, more hens with chicks and more chicks per hen) and that precipitation volume during the early weeks after hatching was negatively correlated with brood size. Precipitation before copulation (i.e. peak of lekking) affected the proportion of hens with chicks and the number of chicks per hen. Sex ratio in broods was also affected by weather conditions, with more female than male chicks in years with low temperatures and high precipitation. By analysing spring weather predictions for the period 2020–2039, we found that weather conditions during the reproductive period remained constant when assuming a continued advancement of reproduction onset, although annual variation was high. We show the importance of weather conditions in influencing Western Capercaillie reproductive success. Western Capercaillie in the Black Forest seem to adjust the timing of reproduction according to changes in weather conditions, but this advancement is unlikely to be limitless, making the future impact of climate change on the species uncertain.

中文翻译：

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天气条件解释了西 Caperacillie (Tetrao urogallus) 繁殖成功和繁殖季节的进展

气候变化和相关的天气模式变化对自然系统具有全球广泛的影响。物候变化会导致繁殖开始与繁殖的有利条件（例如食物供应达到峰值）之间的不匹配，从而影响鸟类的繁殖成功率。长期以来，人们一直在讨论天气条件及其变化，因为它会影响松鸡（Tetraoninae）的繁殖成功并导致许多中欧种群的快速下降。我们监测了 Western Capercaillie Tetrao urogallus的繁殖成功率在德国黑森林，为期 14 年的时间里，研究天气条件如何与繁殖成功相关，并评估不断变化的环境条件是否与繁殖的季节性变化有关。我们观察到 lekking 活动的峰值从 4 月下旬到中旬发生了时间变化，这对应于 0.65 天/年的提前。此外，我们表明繁殖季节的温暖条件与繁殖成功呈正相关（即更大的育雏尺寸、更多的母鸡和每只母鸡更多的雏鸡）并且孵化后最初几周的降水量与育雏尺寸呈负相关。交配前的降水（即泌尿高峰）影响母鸡与小鸡的比例和每只母鸡的小鸡数量。育雏的性别比例也受天气条件的影响，在低温和高降水的年份，雌性雏鸡多于雄性雏鸡。通过分析 2020 年至 2039 年期间的春季天气预报，我们发现，尽管年度变化很大，但在假设繁殖开始持续推进时，繁殖期的天气条件保持不变。我们展示了天气条件在影响 Western Capercaillie 繁殖成功方面的重要性。黑森林中的西Caperacillie似乎会根据天气条件的变化调整繁殖时间，但这种进步不太可能是无限的，这使得未来气候变化对物种的影响变得不确定。我们发现，在假设繁殖开始持续推进时，繁殖期间的天气条件保持不变，尽管年度变化很大。我们展示了天气条件在影响 Western Capercaillie 繁殖成功方面的重要性。黑森林中的西Caperacillie似乎会根据天气条件的变化调整繁殖时间，但这种进步不太可能是无限的，这使得未来气候变化对物种的影响变得不确定。我们发现，在假设繁殖开始持续推进时，繁殖期间的天气条件保持不变，尽管年度变化很大。我们展示了天气条件在影响 Western Capercaillie 繁殖成功方面的重要性。黑森林中的西Caperacillie似乎会根据天气条件的变化调整繁殖时间，但这种进步不太可能是无限的，这使得未来气候变化对物种的影响变得不确定。