Conserving shorebirds in human-dominated landscapes

Abstract

Wetlands support biodiversity and provide critical ecosystem services but have been severely impacted by human activity. Shorebirds are a diverse group of waterbirds that usually forage in shallow water, making them highly dependent on wetlands. Coastal shorebirds are increasingly threatened in the East Asian-Australasian Flyway where coastlines are heavily developed and wetlands have been extensively modified and degraded. In this human-dominated landscape, shorebirds sometimes aggregate in artificial wetlands associated with human production activities including agriculture, aquaculture and salt production. However, it is unknown whether artificial habitat use is widespread by shorebirds across the flyway, if such habitats could help to offset negative population trends, or how artificial habitats should be managed alongside natural habitats to achieve conservation outcomes. This thesis investigates the use of artificial and natural habitats by shorebirds in heavily developed coastal regions of the East Asian-Australasian Flyway, and suggests conservation and management actions in this setting. Chapter 2 presents the first large-scale review of coastal artificial habitat use by shorebirds in the East Asian-Australasian Flyway. Analysing data from multiple monitoring programs and the literature, it shows that 83 shorebird species have occurred on more than 170 artificial sites of eight different land uses throughout the flyway, including 36 species in internationally important numbers. However, occurrence and foraging on artificial habitats is uneven among species, and different land uses support varying abundances and species diversity. Saltworks host a larger and more diverse shorebird assemblage than other artificial habitats, but are threatened by conversion to land uses of lesser habitat value. Chapter 3 presents a detailed case study of artificial habitat use in a critical stopover area comprising ~150 km of coastline in Jiangsu province, China. It shows that most shorebirds are completely limited to artificial habitats during high tide because natural intertidal wetlands are covered by seawater and no natural habitat remains in the supratidal zone. Further, most shorebirds were observed using artificial habitats almost exclusively for roosting (rather than foraging), and selected larger ponds with less water and vegetation cover and fewer built structures nearby, characteristics that can be cultivated through management. These results suggest that jointly managing artificial supratidal and natural iii intertidal habitats would benefit shorebirds in this region, and this approach is likely applicable to sites throughout heavily developed regions of the flyway. Chapter 4 uses long-term monitoring data from five highly developed coastal regions of Australia to show that a high proportion of all shorebirds (more than one-third in four regions and more than two-thirds in two regions) use artificial habitats at high tide. It indicates that a relatively low proportion of migratory and coastal habitat specialist ...