Global Flyway Network

Abstract The East Asian-Australasian Flyway (EAAF) is widely recognised to be the most threatened of the eight flyways in the world, with wetlands rapidly lost due to land cover change, unsustainable use, and the wider impacts of climate change. The recently established Regional Flyway Initiative aims to bring a network of priority wetlands in the EAAF under improved protection, management, and restoration in 10 Asian countries, while mobilising resources for sustainable agriculture, aquaculture, ecotourism, and other livelihoods for local communities. A major step in the development of this initiative is the identification of priority wetland sites through the application of international criteria, based on modern waterbird count data collated from wetland sites across Asia. Through existing analyses and stakeholder consultations, we short-listed 400 internationally important wetlands as candidate sites for further assessment. Count data of EAAF waterbird species was then assessed against international criteria aligned with the Convention on Wetlands (Ramsar Convention), the EAAF Partnership’s Flyway Site Network and Important Bird Areas and Biodiversity for each site to iteratively identify a subset of priority sites, drawing on newly available species population thresholds. Each site was scored and ranked using a metric (Prioritisation Criterion1) calculated from the proportions of every occurring EAAF species against published population thresholds. We identified a total of 147 wetland sites of high conservation priority across the 10 countries, thereby representing the full suite of wetland landscapes and habitats in Asia, both freshwater and coastal, all critical sites for the conservation of migratory waterbirds in the flyway. At least 34 threatened species, including significant proportions of their global populations are represented in this network of 147 sites. To ensure that conservation opportunities are maximised for species and ecosystem services, there is a need to ensure that selected sites and landscapes are reconciled with the conservation and development priorities of each country, and to evaluate priority sites for their ecosystem services.

Population estimates are widely used to underpin conservation decisions. However, determining accurate population estimates for migratory species is especially challenging, as they are often widespread and it is rarely possible to survey them throughout their full distribution. In the East Asian–Australasian Flyway (EAAF), this problem is compounded by its size (85 million square kilometres) and the number of migratory species it supports (nearly 500). Here, we provide analytical approaches for addressing this problem, presenting a revision of the EAAF population estimates for 37 migratory shorebird species protected under Australian national environmental legislation. Population estimates were generated by (1) summarizing existing count data in the non‐breeding range, (2) spatially extrapolating across uncounted areas, and (3) modelling abundance on the basis of estimates of breeding range and density. Expert review was used to adjust modelled estimates, particularly in under‐counted areas. There were many gaps in shorebird monitoring data, necessitating substantial use of extrapolation and expert review, the extent of which varied among species. Spatial extrapolation to under‐counted areas often produced estimates that were much higher than the observed data, and expert review was used to cross‐check and adjust these where necessary. Estimates of population size obtained through analyses of breeding ranges and density indicated that 18 species were poorly represented by counts in the non‐breeding season. It was difficult to determine independently the robustness of these estimates, but these breeding ground estimates were considered the best available data for 10 species that mostly use poorly surveyed freshwater or pelagic habitats in the non‐breeding season. We discuss the rationale and limitations of these approaches to population estimation, and how they could be modified for other applications. Data available for population estimates will vary in quality and extent among species, regions and migration stage, and approaches need to be flexible enough to provide useful information for conservation policy and planning.

Sex determination is often difficult in small seabirds in the field. External measurements and feather coloration were compared between 23 male and 24 female Swinhoe'm Petrels Oceanodroma monohris, following molecular sex determination. No sex differences were detected in any of the nine size parameters. Although females exhibited higher ultraviolet and visible color reflectance from the abdomen feathers and males exhibited higher visible reflectance from the crown feathers, these sexual differences in coloration were barely detectable. These results suggest that neither external measurements nor coloration are reliable for sex determination in this species.