Hydrologically-mediated resource availability regulates annual wading bird breeding in a littoral marsh

Resource density, timing, duration, and accessibility can strongly affect the reproductive responses of consumers. For applied models of resource availability to be most useful, they must account for spatiotemporal variation in each of these factors. Here, we developed a foraging habitat model for wading birds (Ardeidae, Ciconiidae, and Threskiornithidae) in an extensive (>400 km²) fringe wetland in a shallow subtropical lake (Lake Okeechobee, Florida, USA). Our model accounts for hydrological processes that influence wading bird prey resource density, and area and timing of habitat accessibility. The resulting spatiotemporally dynamic model estimates resource availability for wading birds at a local scale (30.5-m grid cells). We assessed whether our model could explain wading bird productivity by hindcasting estimates over fourteen nesting seasons (2006–2019) and quantifying the relationship between aggregated measures of resource availability and breeding productivity (nest abundance and nest survival) for four wading bird species. We found that hydropatterns that increase fish productivity and concentrate fish biomass over hierarchically nested spatiotemporal scales regulate resource availability for wading birds. Wading bird nest abundance increased with the number of available-habitat-days for feeding in the wetland during the breeding season. Furthermore, nest survival for two of three wading bird species increased with available-habitat-days within the foraging range of a nest. Overall, we found that more birds nested with greater success when our models indicated the continual appearance of new foraging habitat throughout the nesting season. The results of this study indicate that managing wetlands for waterbirds will require water management regimes that prioritize hydrological processes that are linked over multiple spatiotemporal scales.