Earlier breeding is one of the strongest responses to global change in birds and is a key factor determining reproductive success. In most studies of climate effects, the focus has been on large-scale environmental indices or temperature averaged over large geographical areas, neglecting that animals are affected by the local conditions in their home ranges. In riverine ecosystems, climate change is altering the flow regime, in addition to changes resulting from the increasing demand for renewable and clean hydropower. Together with increasing temperatures, this can lead to shifts in the time window available for successful breeding of birds associated with the riverine habitat. Here, we investigated specifically how the environmental conditions at the territory level influence timing of breeding in a passerine bird with an aquatic lifestyle, the white-throated dipper Cinclus cinclus. We relate daily river discharge and other important hydrological parameters, to a long-term dataset of breeding phenology (1978–2015) in a natural river system. Dippers bred earlier when winter river discharge and groundwater levels in the weeks prior to breeding were high, and when there was little snow in the catchment area. Breeding was also earlier at lower altitudes, although the effect dramatically declined over the period. This suggests that territories at higher altitudes had more open water in winter later in the study period, which permitted early breeding also here. Unexpectedly, the largest effect inducing earlier breeding time was territory river discharge during the winter months and not immediately prior to breeding. The territory river discharge also increased during the study period. The observed earlier breeding can thus be interpreted as a response to climate change. Measuring environmental variation at the scale of the territory thus provides detailed information about the interactions between organisms and the abiotic environment.

中文翻译：

---

水文影响白喉北斗七星的繁殖时间

早期繁殖是对鸟类全球变化最强烈的反应之一，也是决定繁殖成功的关键因素。在大多数对气候影响的研究中，重点一直放在大型地理指标或大地理区域的平均温度上，而忽略了动物受到其家乡范围内当地条件的影响。在河流生态系统中，除了对可再生和清洁水电的需求不断增加所引起的变化之外，气候变化还在改变水流状态。随着温度的升高，这会导致可用于成功繁殖与河流栖息地相关的鸟类的时间窗口发生变化。在这里，我们专门研究了地域环境条件如何影响具有水生生活方式的雀形目鸟的繁殖时间，白喉北斗星Cinclus cinclus。我们将日常河流流量和其他重要水文参数与自然河流系统中繁殖物候学（1978-2015）的长期数据集联系起来。在繁殖前几周的冬季河水流量和地下水位较高，并且集水区积雪很少的情况下，北斗星繁殖较早。较低海拔地区的繁殖也较早，尽管在此期间影响急剧下降。这表明在研究期的冬季后期，海拔较高的地区有更多的开放水域，这也使得这里可以早日繁殖。出乎意料的是，导致较早繁殖时间的最大影响是冬季月份而不是繁殖之前的区域河流排放。在研究期间，境内河流流量也有所增加。因此，观察到的早期繁殖可以解释为对气候变化的反应。因此，在领土范围内测量环境变化可提供有关生物与非生物环境之间相互作用的详细信息。