Seasonal migration across the north-western Pacific and Indian Oceans in Swinhoe’s Storm-petrel <i>Hydrobates monorhis</i>

Summary Seabirds are experiencing a decline in their populations because of climate change and human activities. Understanding their spatiotemporal dynamics is crucial for effective conservation, but the distribution and movement patterns of pelagic seabirds are not yet fully elucidated. In the present study, we investigated the seasonal movements and wintering areas of Swinhoe’s Storm-petrel Hydrobates monorhis , a Near Threatened species that breeds primarily on islands in the north-western Pacific. The data analyses of geolocators retrieved from four birds showed that Swinhoe’s Storm-petrels migrated across the north-western Pacific and Indian Oceans and wintered in the Arabian Sea. The distance between their breeding colony and the wintering area was approximately 6,700 km, and the tracking distance for a seasonal migration exceeded 12,000 km. The migration pathway was characterised by large-scale movements in both north–south and east–west directions in the Eurasian offshore regions, which previously had been inferred from direct observations at such areas but not empirically confirmed. Wintering areas in the Arabian Sea overlapped with regions where plankton blooms are triggered by the monsoon in winter, which may produce high marine productivity and support the wintering of Swinhoe’s Storm-petrels in this sea area.