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Extensive loss of natural wetlands caused by changes in land use largely diminishes the food resources essential for the survival of migratory waterbirds. Globally, the decline in waterbird populations in East Asia is the most serious, with 64% of these populations showing a decreasing trend. In this study, we applied DNA metabarcoding to examine the spatiotemporal variations and diversities in the dietary compositions of migratory waterbirds in a natural/artificial wetland complex in Asia. By investigating 110 fecal samples from the endangered black-faced spoonbill (Platalea minor) wintering in the wetland, our results show that P. minor had a broad dietary spectrum. The birds fed on at least 26 species in the classes Actinopterygii and Malacostraca, with Mugiliformes, Cichliformes, and Gobiiformes being the main taxa in their diets. Our results also demonstrated clear patterns of the spatiotemporal variations between the roosting groups and intraspecific variations between the individuals, which potentially reflect some of their feeding habits, and the probable usage of different habitat types in the wetland complex. Using high-throughput sequencing, we were able to elucidate the food resources that are critical to P. minor non-invasively, this method can also be used to provide invaluable information for the conservation of many other waterbird species.

Lack of data on population sizes and resource requirements are major impediments to the effective conservation of rare species globally. The conservation of the Eurasian otter (Lutra lutra) in Hong Kong reflects many of these key challenges for elusive and difficult‐to‐study mammals. It is a rare carnivore that has narrowly escaped extirpation, now surviving within a human‐dominated environment. Using sign surveys and spraint analysis, we recorded only 40 fresh spraints from 246 otter signs locations, over 4 months of intensive sampling across 2 years. Records were restricted to the Mai Po wetlands, confirming this as the core area for Hong Kong's otter population. Molecular analysis and microsatellite genotyping identified a minimum of seven individuals, two pairs of which were likely related. The genetic and sign data together strongly indicate a small population. Fish dominated the otter diet, highlighting the importance of fishpond habitats as a premium foraging resource. Given the rapid changes surrounding the Mai Po area (especially the new Northern Metropolis Development Strategy), maintaining quality and connected habitats, in addition to sustaining commercial fishponds will be key to otter recovery and long‐term population viability in Hong Kong.

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