Menz Myles H M, Brown Brian V, Wotton Karl R
Department for Migration and Immuno-Ecology, Max Planck Institute for Ornithology, 78315 Radolfzell, Germany.
Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland.
R Soc Open Sci. 2019 Apr 3;6(4):190153. doi: 10.1098/rsos.190153. eCollection 2019 Apr.
The seasonal migration of huge numbers of hoverflies is frequently reported in Europe from mountain passes or spurs of land. The movement of such large numbers of beneficial insects is thought to provide significant ecosystem services in terms of pollination and pest control. Observations from the East Coast of the USA during the 1920s indicate the presence of migratory life histories among some hoverfly species there, but 90 years have now passed since the last reported observation of hoverfly migration in the USA. Here, we analyse video footage taken during a huge northward migration of hoverflies on 20 April 2017 on the West Coast of California. The quantification of migrant numbers from this footage allows us to estimate the passage of over 100 000 hoverflies in half an hour over a 200 m section of headland in Montaña de Oro State Park (San Luis Obispo County). Field collections and analysis of citizen science data indicate different species from the previously reported migrations on the East Coast of the USA and provide evidence for migration among North American hoverflies. We wish to raise awareness of this phenomenon and suggest approaches to advance the study of hoverfly migration in North America and elsewhere.
在欧洲，经常有报道称大量食蚜蝇会从山口或陆岬季节性迁徙。如此大量的益虫迁徙被认为在授粉和害虫控制方面提供了重要的生态系统服务。20世纪20年代美国东海岸的观测表明，当地一些食蚜蝇物种存在迁徙的生活史，但自上次报道美国食蚜蝇迁徙观测以来，已经过去了90年。在这里，我们分析了2017年4月20日在加利福尼亚州西海岸食蚜蝇大规模向北迁徙期间拍摄的视频片段。通过对这段视频中迁徙数量的量化，我们估计在奥罗山州立公园（圣路易斯奥比斯波县）200米长的陆岬区域内，半小时内有超过10万只食蚜蝇飞过。实地采集和对公民科学数据的分析表明，这些食蚜蝇的物种与之前报道的美国东海岸迁徙中的物种不同，并为北美食蚜蝇的迁徙提供了证据。我们希望提高对这一现象的认识，并提出推进北美及其他地区食蚜蝇迁徙研究的方法。
