盐城沿海海堤林带柳莺属(Phylloscopus)鸟类秋季迁徙规律

Abstract

江苏盐城沿海具有广阔的平原与湿地滩涂，但缺少自然林地。经过多年的防风林建设，沿海海堤逐渐形成了特有的、南北走向的条带林生境，为迁徙鸟类提供了通道和停歇地，是研究鸟类迁徙规律的理想地点。柳莺属鸟类个体小，野外种类识别难，其迁徙规律缺乏深入研究。分别于2018年和2019年两个秋季，采用雾网法对盐城沿海海堤林带柳莺属鸟类的迁徙规律进行研究。结果表明：两个秋季共捕获柳莺属鸟类8种608只，其中极北柳莺（Phylloscopus borealis）、冕柳莺（P. coronatus）、淡脚柳莺（P. tenellipes）和黄眉柳莺（P. inornatus）的捕获数量分别为245只、131只、107只和94只，占捕获总数量的95%，是秋季迁徙期的优势种。对优势种柳莺日捕获率进行比较：2019年极北柳莺的日捕获率显著高于淡脚柳莺和黄眉柳莺（U test，P<0.05）。对捕获数量随时间变化进行分析，4种柳莺都以集中在短时间内快速通过的迁徙策略穿越盐城沿海海堤林带，符合秋季小型雀形目鸟类迁徙采取时间最小化假说。不同种类的柳莺在通过盐城沿海海堤林带的时间顺序上存在显著差异（K-W test，P<0.05），2018年和2019年均以黄眉柳莺通过最晚。随着时间的推移，四种柳莺的脂肪度都逐渐下降。繁殖地纬度的差异可能是导致4种柳莺通过盐城沿海海堤林带时间差异的原因。盐城沿海海堤林带为柳莺属等雀形目小型鸟类的迁徙提供了非常理想的迁徙通道，应当加强海堤林带在鸟类迁徙和保护中的作用研究。;There are vast plains and wetlands in the coastal area of Yancheng City, Jiangsu Province, China, but there lack natural forest lands. After several decades of construction, the Yancheng coastal seawall forests have formed a very unique habitat with north-south direction narrow forest belts. These forest belts have been served as important migrating channels or stopover sites for long-distance migratory birds. Therefore, an ideal place for the study of bird migration has been provided in this site. However, due to the small body size of warblers, it is difficult to identify them in the field which limits our understanding of their migration patterns. Here, by using mist-nets, we collected eight dominant migratory warbler species in autumn in 2018 and 2019, and studied the temporal rhythm of their migration. In total, 608 warblers belonging to 8 species were captured by using mist-nets in autumn in 2018 and 2019, including 245, 131, 107 and 94 individuals for Phylloscopus borealis, P. coronatus, P. tenellipes and P. inornatus, respectively. The total captured number of these four species accounted for 95% of all the captured warblers, indicating that they were the dominant migratory warbler species in this study site in autumn. The daily captured number of P. borealis in 2019 was significantly higher than those of P. tenellipes and P. inornatus (U test, P<0.05). Based on the changing of captured number with time, all these four dominant warblers tended to adopt the migration strategy that pass through the study site rapidly in a concentrated time. This is consistent with the hypothesis that small passerines usually choose time minimizing strategies to get to the winter sites as soon as possible in autumn. There was a significant difference in the temporal rhythm of the four warbler species in both years (K-W test, P<0.05). The warbler P. inornatus was the last one that passed through the study site both in 2018 and 2019. The fat scores of all the four warbler species significantly decreased with the migration time. We consider that the differences in the temporal rhythm of the four warbler species might attribute to the differences in the geographic locations of their breeding sites. In conclusion, the Yancheng seawall forest belt provided an appropriate migration channel for small passerines such as the warblers. More studies should be conducted to explore the important roles of the Yancheng seawall forest belts for bird migration and conservation in the future.