Shorebird responses to fine‐scale water level fluctuations and macrofauna biomass in a newly constructed freshwater wetland

Abstract Introduction Restoration of marine and freshwater wetlands for shorebirds is essential for the recovery of their declining populations. An ongoing approach is to restore shorebird habitats by large‐scale engineering, expecting the return of birds once suitable abiotic conditions are (re)established. However, this requires science‐based knowledge on which abiotic conditions should be (re)constructed. Objectives Here, we aimed to identify preferred water‐level ranges of a diverse shorebird community by studying shorebird habitat use in a new 1300 ha heterogeneous freshwater wetland with spatio‐temporal variation in food availability and water levels (Marker Wadden, The Netherlands). We hypothesized that (1) water levels regulate the attractiveness of wetland sites to shorebirds; (2) shorebird numbers are positively related to benthic and pelagic macrofauna biomass; (3) water level and macrofauna biomass interact, with the effect of macrofauna biomass diminishing as water levels increase. Methods We combined artificial intelligence shorebird counting on 86,400 camera trap images with automatic water level registrations and monthly macrofauna biomass sampling. Results Statistical modeling identified water level as the key driver of shorebird numbers, and macrofauna biomass as less important during our 1‐year study. Optimal water levels ranged between just exposed saturated mudflats and mudflats with 5 cm of water on the sediment surface. Water level‐regulated macrofauna accessibility overruled effects of macrofauna biomass on shorebird numbers. Conclusions Fine‐scale water level management can be a powerful approach to restore habitat suitability for foraging shorebirds, and thus contribute to the recovery of their declining populations.