{"title":"Pattern and predictability of potential wind assistance for waders and geese migrating from West Africa and the Wadden Sea to Siberia","authors":"T. Piersma, Sjon Van de Sant","doi":"10.34080/OS.V2.21614","DOIUrl":null,"url":null,"abstract":"We have analysed published wind data from the period 1979–1991 to evaluate to what extent migrating waders and geese might benefit from tailwind assistance when flying at altitudes ranging from ground level up to 5.5 km from West Africa (Banc d’Arguin, Mauritania) to the Wadden Sea (Netherlands, Germany and Denmark) in late April and early May, and from the Wadden Sea to Taymyr Peninsula (central Siberia) in late May and early June. Between West Africa and the Wadden Sea it is usually advantageous to fly high, with an average tailwind of 15 km/h (mean of yearly averages) for those birds flying along the optimal height track. There were large differences between years though, with 36 km/h tailwind (1983) and 2 km/h headwind (1991) as extreme values. The best altitudes for migration were higher along the northwest African coast than over Europe. There was no evidence for consistent seasonal changes in wind favourability, but “bad” years were consistently bad over the whole season. Between the Wadden Sea and the Taymyr Peninsula wind conditions were better still than for the Banc d’Arguin-to-Wadden Sea journey (long term average for flights along optimal height track is 21 km/h tailwind), with the favourable winds found at intermediate altitudes (1.5–3 km). The wind conditions were less variable between years along the Wadden Sea–Taymyr route. We discuss both the limitations of the current analyses and the scope for future work.","PeriodicalId":52418,"journal":{"name":"Ornis Svecica","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2020-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"3","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Ornis Svecica","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.34080/OS.V2.21614","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"Agricultural and Biological Sciences","Score":null,"Total":0}
引用次数: 3
Abstract
We have analysed published wind data from the period 1979–1991 to evaluate to what extent migrating waders and geese might benefit from tailwind assistance when flying at altitudes ranging from ground level up to 5.5 km from West Africa (Banc d’Arguin, Mauritania) to the Wadden Sea (Netherlands, Germany and Denmark) in late April and early May, and from the Wadden Sea to Taymyr Peninsula (central Siberia) in late May and early June. Between West Africa and the Wadden Sea it is usually advantageous to fly high, with an average tailwind of 15 km/h (mean of yearly averages) for those birds flying along the optimal height track. There were large differences between years though, with 36 km/h tailwind (1983) and 2 km/h headwind (1991) as extreme values. The best altitudes for migration were higher along the northwest African coast than over Europe. There was no evidence for consistent seasonal changes in wind favourability, but “bad” years were consistently bad over the whole season. Between the Wadden Sea and the Taymyr Peninsula wind conditions were better still than for the Banc d’Arguin-to-Wadden Sea journey (long term average for flights along optimal height track is 21 km/h tailwind), with the favourable winds found at intermediate altitudes (1.5–3 km). The wind conditions were less variable between years along the Wadden Sea–Taymyr route. We discuss both the limitations of the current analyses and the scope for future work.
我们分析了1979-1991年期间公布的风力数据,以评估4月下旬和5月初从西非(毛里塔尼亚的阿古因岛)到瓦登海(荷兰、德国和丹麦),以及5月下旬和6月初从瓦登海到泰米尔半岛(西伯利亚中部),迁徙的水禽和鹅在从地面到5.5公里的高度上飞行时,在多大程度上受益于顺风的帮助。在西非和瓦登海之间,飞得高通常是有利的,对于那些沿着最佳高度轨道飞行的鸟来说,平均顺风为每小时15公里(年平均值)。然而,年份之间存在很大差异,极值为36公里/小时的顺风(1983年)和2公里/小时的逆风(1991年)。最适合移民的海拔高度是非洲西北海岸,而不是欧洲。没有证据表明风有利度有持续的季节变化,但“坏”年份在整个季节都一直不好。在瓦登海和泰米尔半岛之间的风力条件仍然比Banc d ' arguin到瓦登海的旅程好(沿着最佳高度轨道飞行的长期平均值为21公里/小时的顺风),在中等高度(1.5-3公里)发现有利的风。瓦登海-泰米尔航线上的风况在不同年份之间变化较小。我们讨论了当前分析的局限性和未来工作的范围。