Data from: Biocontrol: the response of native oystercatchers to a non-native clam invasion

Global change, including invasive species introduction, has already had observable effects on migrant bird species, from Northern breeding areas to wintering grounds. In this study we analyze the response of the Eurasian oystercatcher abundance to the density of an invasive clam species (Corbicula fluminea) and its potential role as biological control. As a case study, the oystercatcher population fluctuations over a 30-year time period, coupled with video-recorded estimates of its feeding behavior on C. fluminea, and results from an exclosure experiment, were analyzed in the NW of the Iberian Peninsula. Results showed that oystercatchers exert a top-down control over C. fluminea density. In addition, oystercatchers doubled its wintering numbers in a C. fluminea invaded estuary where they actively feed upon this invasive clam. Given that, the facilitative interaction between the invasive C. fluminea and the migratory Eurasian oystercatcher seems to respond to bottom-up forces. Altogether, our results suggest that control measures applied to long term biological invasions must be carefully analyzed since non-native species may be sustaining dependent native communities.

全球变化（包括外来物种引入）已对从北部繁殖地前往越冬地的迁徙鸟类产生了可观测的影响。本研究旨在分析欧亚蛎鹬（Eurasian oystercatcher）的种群丰度对外来蛤蜊物种河蚬（Corbicula fluminea）种群密度的响应，以及该鸟类作为生物防治媒介的潜在作用。本研究以伊比利亚半岛西北部为研究区域，针对欧亚蛎鹬30年的种群波动、基于视频记录的该鸟类取食河蚬的行为估算结果，以及围栏排除实验（exclosure experiment）的结果开展了分析。研究结果显示，欧亚蛎鹬对河蚬的种群密度具有自上而下的调控作用。此外，在被河蚬入侵的河口生境中，欧亚蛎鹬的越冬种群数量翻了一番，且该鸟类会主动取食这一入侵蛤蜊物种。据此可见，入侵物种河蚬与迁徙性欧亚蛎鹬之间的促进性相互作用，似乎受上行因子调控。综合来看，本研究结果表明，针对长期生物入侵的防治措施需谨慎评估，因为外来入侵物种可能维系着依赖其生存的本土生物群落。