Nadal et al. (2018) recently reported on changes in the phenology of the Common quail (Coturnix coturnix) in seven cloudy regions of Spain in relation to climate change. The authors used a long-term ringing database (1961–2014) and calculated the mean date for three biological stages: arrival at the breeding areas, stay and autumn departure. They observed that some of these phenological variables were associated with the climate variables of temperature and rainfall (Figs. 4 and 6 of their article). They also analysed the yearly variation in temperature and rainfall over the last 86 years, reporting an increase in temperature and a decrease in rainfall (Figs. 3 and 5 of their article). Based on these results, the authors suggested that the Common quail phenology has varied as a response to climate change in Spain, thus concluding that “quail movements and breeding attempts are eco-synchronized sequentially in cloudy regions. Our results suggest that quails attempt to overcome the negative impacts of climate change and agricultural intensification by searching for alternative high-quality habitats”.

We disagree with two methodological aspects of the article by Nadal et al. (2018): (1) the estimation of the mean date of arrival, stay and departure in the different regions studied; and (2) the analyses carried out to correlate the phenology of the species with the changes in climate variables.

纳达尔等。（2018）最近报道了普通鹌鹑（Coturnix coturnix）的物候变化）与气候变化有关的西班牙七个多云地区。作者使用了一个长期的铃声数据库（1961-2014），并计算了三个生物学阶段的平均日期：到达繁殖区，停留和秋季离开。他们观察到，其中一些物候变量与温度和降雨的气候变量相关（他们文章的图4和图6）。他们还分析了过去86年中温度和降雨量的年变化，报告了温度升高和降雨减少的情况（他们的文章的图3和5）。根据这些结果，作者认为，普通鹌鹑的物候因西班牙的气候变化而有所变化，因此得出结论：在多云地区，鹌鹑的运动和繁殖尝试被顺序地进行了生态同步。我们的结果表明，鹌鹑试图通过寻找替代的高质量栖息地来克服气候变化和农业集约化的负面影响”。

我们不同意Nadal等人文章的两个方法论方面。（2018）：（1）估计研究的不同区域的平均到达，停留和离开日期; （2）进行了分析，以将物种的物候与气候变量的变化相关联。