Northward migration of shorebirds through Bohai Bay, China – Annual report 2017

TeamPiersma GFN Bohai Bay Annual Report

The Global Flyway Network team, consisting of Chris Hassell, Adrian Boyle, Bob Loos, and Theunis Piersma report the findings from the 2017 field work. Chris: “Unfortunately but not unexpectedly, results were similar to those of 2016: the Red Knot that spend the non-breeding season in north west Australia (NWA) arrived at the Luannan Coast in much lower numbers than in previous years and earlier in the season.”

Blog GFN Bohai report_map
Interpreted satellite image of Bohai Bay, with our newly added study site Hangu indicated in red.

The Luannan coast of Bohai Bay is vital for Red Knots

In summary the GNF team consisting of Chris Hassell, Adrian Boyle, Bob Loos, and Theunis Piersma recorded 2,765 marked shorebirds from throughout the East Asian-Australasian Flyway (EAAF) compared to 3,554 during the 2016 field work season. This year 295 birds were individually recognizable from the Global Flyway Network (GFN) colour-banding project in NWA. This is exactly the same number as in 2016. This was of course dominated by Red Knot Calidris canutus with 269 individuals identified, then Great Knot Calidris tenuirostris with 22 and Bar-tailed Godwit Limosa lapponica with 4. As in previous years, this reflects the vital importance of the area for Red Knots from NWA.

Red Knot fling in to foarge
Red Knots flying to forage on a falling tide at Nanpu, 30 April 2017. Photo: Adrian Boyle

Reduction in use of alternative feeding habitat in commercial ponds

Besides the inter-tidal area, the importance of the vast area of commercial ponds adjacent the mudflats is documented by GFN and by Beijing Normal University (BNU) students in previous years In 2017 the use of ponds by shorebirds was less than in previous years. The number of birds utilising the ponds was reasonably high during April but much lower during May than in previous years. The team expected big numbers of Red Knot to use the ponds during mid to late May, as was seen in previous years, excluding 2016. This, however, did not eventuate. Red-necked Stints and Curlew Sandpipers were not present in big numbers either. This was probably due to the generally high water levels in the ponds giving fewer foraging opportunities.

Some species were (much) more common than usual

On 2 April large numbers of Black-tailed Godwits Limosa limosa (a minimum 17,100!) were using the Hangu site. This single count is higher than any we have recorded in previous years and represents 11% of the current EAAF population estimate. Also the highest count of Asian Dowitcher Limnodromus semipalmatus was recorded – 1,754 on 8 May also at Hangu. On May 7 a count of 40,000 Dunlin Calidris alpina was the biggest count of this species over all our study years.

Part of the flock of Blcak-tailed Godwits
Part of the flock of Black-tailed Godwits at Hangu, 13 April 2017. Photo: Adrian Boyle

Conservation recommendations – speed of reclamation of mudflats

The continuing pressures on the intertidal area are obvious with the development of industrial and housing areas adjacent to and on reclaimed mudflats. In our study area the direct destruction of the intertidal habitat has slowed in the last five years. The building projects that are taking place in former pond habitat and mudflat areas reclaimed in recent years appear to have slowed. There were many fewer trucks, cranes, plant machinery and workers in the area. We assume this slowdown is due to the general downturn of the wider Chinese economy. However, a six-lane highway has been constructed part way along our study site, bridges are in place and a new road through the ponds is under construction. It would only take an upturn in the world, Chinese or local economies to see renewed expansion and loss of mudflats in this critically important area. Currently multi-billion yuan projects are in the planning stages for development within the Luannan Coast area.

Black-tailed Godwit foraging at Hangu
 Black-tailed Godwits forage next to the highway at Hangu, 15 April 2017. Photo: Adrian Boyle

The ponds in the salt works area host all the migrant birds at high tide when the mudflats are inundated by the sea, making the area a critical component of the Luannan Coast Shorebird Site. These ponds should be included in any conservation initiatives. They are also contributors to the local economy and jobs.

Red Knot roosting at Hangu ponds
Red Knots roosting at Hangu ponds, 10 May 2017. Photo: Adrian Boyle

GFN plans for coming years

The Global Flyway Network aims to continue to conduct research activities and follow up analysis to document the fates of four shorebird species (Bar and Black-tailed Godwit, and Red and Great Knot) at their non-breeding sites in NWA and throughout the flyway, with an emphasis on the Luannan Coast, Bohai Bay. This will depend on continued financial support. From this work we will be able to assess the effects of human induced habitat change through statistical analysis.

GFN will continue to support conservation efforts with in-depth analyses of the data collected at Bohai Bay in conjunction with Department of Conservation-New Zealand, World Wide Fund for Nature (WWF)-China, and Wetlands International-China. Dr Tamar Lok, a postdoctoral researcher from the University of Groningen, Post-doc Dr Hong- Yan Yang at Beijing Forestry University and PhD student Ying-Chi Chan, will continue to analyse GFN data under the co-supervision of Professor Theunis Piersma. All work will be in close cooperation with Beijing Normal University and Fudan University.

The full report titled “RED KNOT NORTHWARD MIGRATION THROUGH BOHAI BAY, CHINA, FIELD TRIP REPORT APRIL – JUNE 2017” can be downloaded here.

Impression of fieldwork:

Chris and Adrian scanning
Chris and Adrian scanning from the Nanpu Seawall. Photo: Bob Loos
Bob returns from scanning
Bob Loos returning from a rained-off scanning session at Nanpu ponds, 20 May 2017. Photo: Adrian Boyle

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