Polychaete Worm Density Correlates with Aggregate Shorebird Density, Prey Intake Rate and Foraging Success at an Intertidal Mudflat in Bangladesh

Migratory shorebirds have suffered considerable declines because their migratory habits make them susceptible to threats in many different parts of the world. Successful conservation initiatives therefore require an understanding of their ecology not just at their breeding sites, but also at wintering and staging sites. Previous studies have shown that relationships between shorebirds and their wintering habitats are complex and context specific, underlining the importance of continued investigation of their ecology in new contexts. In this study, we investigated the relationship between prey density and shorebird abundance at stretches of mudflat spread across two islands in coastal Bangladesh. To explore whether prey density influenced shorebirds' ability to find and ingest prey, we also examined relationships with intake rates and foraging success. We found that the density and richness of shorebird communities increased with increasing polychaete worm density across small stretches of mudflat within each island. We also found evidence that prey intake rates and foraging success increased with available food, implying that food as a resource may be limiting in this landscape. Shorebirds may be required to spend more energy foraging in suboptimal habitats, explaining (in part) why densities are higher in habitats with more available prey. Our study suggests that prey density is an important correlate of shorebird density in this important South Asian wintering ground. Our results may have management implications, but this requires further study.