Mapping Whimbrel Migration Routes and Protection Gaps Along China's Coast
Satellite tracking of Whimbrels in Hangzhou Bay reveals high site fidelity, two distinct migration routes, and critical inland stopovers still lacking formal protection.
Two Routes, One Coastal Gateway
Researchers in Zhejiang have used satellite tracking data from 13 Whimbrels (Numenius phaeopus) ringed in Hangzhou Bay between 2018 and 2023 to chart their movements along the East Asian–Australasian Flyway. After leaving the bay in spring, the birds followed the Chinese coast and crossed the Northeast Plain before splitting into two routes between 45°N and 50°N – a western route to central Siberia and an eastern route to the Russian Far East. Despite this divergence, migration distances, durations, and stopover patterns were broadly similar between the two groups, though eastern-route birds migrated more slowly southward.
Hangzhou Bay emerged as a linchpin in the migration cycle. Nearly 77% of tracked individuals returned here on southward journeys, and detailed mapping showed strong overlap in core feeding areas between spring and autumn. The site’s mudflats, especially those east of the Hangzhou Bay Wetland Park and near Ximen Town, supported the highest concentrations of birds.
Stopovers: Coastal Strengths, Inland Weaknesses
Analysis of 52 Whimbrel stopover sites in China, combining new tracking with published studies, found that 73.1% fell within protected areas, mainly national nature reserves and wetland parks. Coastal coverage was strong – 82.4% of East Sea–South Sea sites and 72.7% of Bohai–Yellow Sea sites were protected – but inland coverage in Inner Mongolia and Northeast China lagged at just 57.1%. These inland areas are used late in the northward journey, making them crucial for breeding readiness.
Stopovers within national-level protected areas recorded the longest total stay times, underlining their importance. Eight national reserves, including the Yellow River Delta, Yancheng Wetland Rare Bird Reserve and Dandong Yalujiang Wetland, hosted multiple stopover events. However, some heavily used areas, such as Hangzhou Bay’s core Whimbrel feeding grounds, remain outside national-level protection boundaries.
Conservation Urgency and Policy Goals
The study supports China’s “Action Plan for the Protection and Restoration of Migratory Bird Flyways (2024–2030)”, which aims for 90% coverage of critical flyway habitats by 2030. While coastal wetlands already perform relatively well for Whimbrel conservation, the inland stopover network shows gaps that could undermine the resilience of migration routes. Inland losses are harder to offset, as Whimbrels exhibit strong fidelity to particular sites.
Researchers highlight that Hangzhou Bay’s importance extends beyond Whimbrels, supporting large populations of other shorebirds such as Dunlin, Kentish Plover and Grey Plover, often at internationally significant levels. They recommend extending protection to unprotected core zones in Hangzhou Bay and targeting inland gaps to secure the species’ migration corridor.
Whimbrel Watch: Subspecies on the Same Path
The tracking also confirmed that two subspecies – N. p. variegatus and N. p. rogachevae – share much of the coastal migration route before diverging north of 50°N. This mirrors patterns in other shorebirds, such as Black-tailed Godwit and Dunlin, where subspecies overlap along migration corridors but breed in different regions. Genetic studies are needed to confirm subspecies assignments in the Hangzhou Bay population.
By integrating high-resolution movement data with habitat protection mapping, the study offers a clear blueprint for targeted conservation – one that prioritises both the strongholds and the weak links in China’s Whimbrel migration network.
August 2025
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