Data from: Effects of land use and climate on the distribution of the Jungle Nightjar Caprimulgus indicus in Hokkaido, northern Japan

Although the relative importance of land use and climate to large-scale bird distributions has received great attention, it is difficult to separate the effects of land use and climate, and there are few studies on bird abundance distributions on a large scale. Here, we examined the effects of land use and climate on the abundance of the nocturnal Jungle Nightjar Caprimulgus indicus in Hokkaido, northern Japan. We chose 125 sampling sites with low correlations (|r| < 0.58) between land use and climate, and combined a playback method with a hierarchical model (N-mixture model). We thereby accounted for the possibility that we could not detect all individuals during the field survey. Results show that Jungle Nightjar abundance was greater at sites within a 4-km radius of moderate forest cover (~75%) and with high average temperatures during the breeding season. Moreover, the effects of land-use were greater than those of climate. Mapping predictions of Jungle Nightjar abundance indicated that suitable areas are distributed in southern and central Hokkaido and around the margins of montane zones. Factoring in the covariation of land use and climate, land use may be the most important driver of the distribution of the Jungle Nightjar in Hokkaido.尽管土地利用与气候对鸟类大范围分布的相对重要性已受到广泛关注，但二者的效应难以区分，且目前针对大尺度下鸟类丰度分布的研究仍较为匮乏。本研究以日本北部北海道地区的夜间活动鸟类普通夜鹰（Jungle Nightjar，学名*Caprimulgus indicus*）为研究对象，探讨土地利用与气候因子对其种群丰度的影响。我们筛选出125个土地利用与气候因子相关性较低（|r| < 0.58）的采样点，并结合鸣声回放法与层级模型（N-mixture模型），以此解决野外调查中无法检出所有个体的问题。研究结果显示，在繁殖季平均气温较高，且周边4千米半径范围内森林覆盖率适中（约75%）的采样点中，普通夜鹰的种群丰度更高。此外，土地利用因子对种群丰度的影响强度高于气候因子。种群丰度的空间预测结果显示，适宜栖息地分布于北海道南部、中部以及山地带的边缘区域。综合考虑土地利用与气候因子的共变关系后，土地利用或为北海道地区普通夜鹰种群分布的首要驱动因子。