Relative importance of prey abundance and habitat structure as drivers of shorebird breeding success and abundance

Understanding large-scale drivers of animal breeding densities and demography has a range of important uses, including informing conservation management. Given the threat of climate change, the importance of developing a process-based understanding of variation in animal populations is increased to inform adaptive management. For a climate-change sensitive species, the European Golden Plover Pluvialis apricaria, we use novel field-collected data on large-scale spatial variation in prey abundance and vegetation structure to understand drivers of breeding abundance and breeding success, and inform potential management responses. The abundance of the key prey, crane flies (Tipulidae), increased with altitude (a surrogate for temperature) and peat depth (a surrogate for soil moisture). Golden plover breeding densities were highest where vegetation was shortest, probably reflecting greater prey accessibility. In contrast, breeding success was not strongly related to vegetation height, but positively correlated with both crane fly abundance and daily minimum temperatures. When combined to model the number of likely successful pairs in any 1 year, the magnitude of vegetation height effect far exceeded that of crane fly abundance. Thus, for golden plover and other shorebirds sharing similar habitats, management to optimize breeding habitat (grazing or burning to promote short vegetation) may differ from management to promote breeding success (drain blocking to increase soil moisture and prey abundance). Adaptive management in the face of climate change should therefore include appropriate vegetation management, as well as maximizing prey abundance. More broadly, as the drivers of breeding density and demographic parameters may differ, we advocate that conservation practitioners collect not just information on species' distributions but also underpinning demographic processes when using science to inform management.