Data from: Birds influence vegetation coverage and structure on sandy biogeomorphic islands in the Dutch Wadden Sea.

Small uninhabited islands form important roosting and breeding habitats for many coastal birds.  Here, we assess the role of external nutrient input by coastal birds on the vegetation structure and coverage on sandy biogeomorphic islands in the Dutch Wadden Sea, where island-forming processes depend on vegetation-sedimentation feedbacks.  We Used a combination of bird observations and plant stable isotope (δ15N) analyses, to demonstrate that (i) breeding birds transport large quantities of nutrients via their faecal outputs to these islands annually and that (ii) this external nitrogen source influences vegetation development on these sandy, nutrient-limited, islands. We further discuss how this avian nutrient pump could impact island development and habitat suitability for coastal birds and discuss future directions for research. For the conservation of both threatened coastal birds and sandy back-barrier islands and the design of appropriate management strategies, we argue that three-way interactions between birds, vegetation and sandy island morphodynamics need to be further elucidated. 

Methods

Data stored in this repository are bird counts from all three islands [Breeding_total.csv] and the relation between total faecal excretion rates (estimated using bird counts) and average vegetation coverage (estimated using satellite imagery) [Vegetation_bird.csv]. Additionally, we gathered data in the field including vegetation charactersitics [field.data.xls], isotopic data of the vegetation [new_isotopes.csv] and soil charactersitics [Soil_prop.csv]. Detailed description of these methods and the results can found in the accompanying publication (Reijers et al. STOTEN).