Autumn migration of the migrant hawker (Aeshna mixta) at the Baltic coast

作者：Y. Oelmann, D. Fiedler, Rune Michaelis, Meelis Leivits, A. Braun, Philipp Gschwind, Harald Neidhardt, Christoph Willigalla · 发表于：Movement Ecology · 年份：2023 · DOI：10.1186/s40462-023-00415-z · 被引用次数：6 · 研究领域：Medicine

Background Migratory insects are important for the provision of ecosystem services both at the origin and destination sites but – apart from some iconic species – the migration routes of many insect species have not been assessed. Coastlines serve as a funnel where migrating animals including insects accumulate. Migratory behaviour and captures of dragonflies in bird traps suggest autumn migration of dragonflies along coastlines while the origin and regularity of this migration remain unclear. Methods Dragonfly species were caught at the bird observatory Kabli at the Baltic coast in Estonia in 2009, 2010 and 2015. For the 2015 data set, we used a stable hydrogen (H) approach to trace the potential natal origin of the migrant hawker ( Aeshna mixta ). Results 1079 (2009), 701 (2010) and 88 (2015) A. mixta individuals were caught during the study periods (35, 37 and 11 days in 2009, 2010 and 2015, respectively). The migration period lasted from end of August to end of September. Based on the results from our stable isotope analysis, we identified two populations of A. mixta : One (range of isotope signatures of non-exchangeable H [δ^2H_n wing]: −78‰ to −112‰) had a local likely origin while the other (δ^2H_n wing: −113‰ to −147‰) migrated from northerly directions even in headwind from the South. The former showed an even sex ratio whereas the actively migrating population was dominated by males. Conclusions Our results suggest a regular southbound autumn migration of A. mixta a...