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Brent Goose migration along the north coast of the Sea of Okhotsk

ArCS II Overseas Fellowship Program for FY2021 participant
Yusuke SAWA (Researcher at Yamashina Institute for Ornithology)

Our group has studied the migratory birds “Brent Goose” that breeds in the Arctic ground and winters in Japan since 2016. The migratory birds face a variety of threats on their migratory pathway, such as habitat degradation in Arctic breeding ground due to climate change and unsustainable hunting and development in staging and wintering ground. To conserve these migratory birds, it is essential to identify the migratory route and assess the threats at important areas by field survey. We have identified the migratory route of Brent Goose by satellite tracking research. In this study, we researched the Brent Goose population and their habitat in the wetlands around Magadan, north coast of the Sea of Okhotsk where one of the spring staging areas identified by our previous study.

The study period was from 23 May to 6 June. The mean temperature in Magadan was around 4 degrees Celsius while over 25 degrees Celsius in Tokyo! There remained a lot of ice on the sea. The main study area, “Ola Lagoon” was shallow water with approximately 5m depth. The maximum tidal differences was 5m and we could walk in the lagoon when the lowest spring tide. There were amount of Zostera spp., the main food of Brent Goose and also spawning bed of herrings. When the lowest tide, a lot of carcasses of herrings were appeared in the Lagoon. We were overwhelmed by mass of the Slaty-backed Gulls gathering the lagoon to eat them. Approximately 300 Brent Geese were found among huge flock of Gulls. We could approach to Geese at the distance of nearly 50 meters and observed their foraging behavior.

Carcasses of herrings after oviposition in Ola Lagoon
Brent Goose foraging in Ola Lagoon

The wintering population of Brent Goose in East Asia was estimated at 8,700. There is only limited information available how many geese migrate to Arctic ground through the north coast of Sea of Okhotsk. In this study, we confirmed the flocks from several to hundreds of Geese staging along the coastal area of 200km around Magadan. The similar environment also appears around Okhotsk city, 400km west from Magadan and Shelikhov Gulf. We would like to contribute to better understanding of spring migration of Brent Goose in the Sea of Okhotsk by more information gathering around this region and environmental analysis.