Global Flyway Network in Australia Update

The Global Flyway Network (GFN) was initiated by Theunis Piersma, professor of Global Flyway Ecology at the University of Groningen, in the Netherlands in 2006. This includes work in the NW Australia and China where its team, carries out extensive studies of migratory shorebirds in Northwest Australia as well as the coasts of China. This includes extensive catching and marking migratory shorebirds, notable with engraved coloured ‘leg flags’, which identify induvial birds in the field by any observer in the East Asian Australasian Flyway. Over the years members of the GFN, employed by Chris Hassell, in Broome, NW Australia, have spent many thousands of hours scanning extensive tidal mudflats in North West Australia as well the coasts of China. The resultant database includes flagged shorebirds in any of the Flyway countries that pass through these study areas during migration.

The (GFN) is a partnership between researchers worldwide who are devoted to long term — usually demographic — work on long distance migrating shorebirds. The partnership aims to build on the strengths of comparative demographic shorebird studies worldwide, with the aim to understand and analyse the factors determining shorebird numbers in a rapidly changing world. In practice it also tries to fill major gaps in coverage of fieldwork of the world’s most threatened shorebird flyways.

Summary of the GFN Report – June 2020

Due to the COVID-19 pandemic, Global Flyway Network (GFN) researchers from Australia, The Netherlands and the United Kingdom were unable to travel to China. Luckily, our colleague Katherine Leung was able to lead the fieldwork. She had to endure 28 days of quarantine to achieve this. Fourteen days on arriving in Shanghai from Hong Kong and 14 days when moving from Shanghai to Nanpu Development City. GFN thanks her for showing such endurance.

Katherine was ably assisted in the fieldwork by six additional scanners, Mr. Guan Xiangyu, a Beijing bird guide, Miss Gao Chang, a freelance investigator from Beijing and graduate from Beijing Normal University (BNU) under our long-time collaborator Prof. Zhang Zhengwang, Miss Wu Entao, Miss Guo Jia and  Miss He Ying, research assistants at Beijing Forestry University, and our close colleague Hebo Peng. We thank them all for their efforts in difficult times. The

costs this year were covered by the Center for East Asian-Australasian Flyway Studies (CEAAF) at Beijing Forestry University (BFU) under the leadership of Prof. Lei Guangchun

The team was in the field from 4 May to 7 June, 34 days (less than a usual spring field season of 56 days).

The Luannan Coast referred to throughout this report encompasses our study sites shown in Figure 1 and the adjacent salt and aquaculture ponds.

The main findings from this year’s fieldwork showed that on the Luannan Coast in 2020, Red Knot Calidris canutus were never present in such large numbers as in 2019. The biggest single count in 2020 was of 20,000 on 24 May. This is in stark contrast to the 47,537 counted on 22 May 2019. The numbers of Red Knot using the Luannan Coast varies a lot from year to year. Relatively large numbers were present in 2014, 2015 and 2018. However, relatively low numbers recorded during 2016 and 2017. Given that food resources usually determine distributions, the benthic food at Luannan and other sites determine the numbers of Red Knot that come to Luannan.

Due to limited time spent at Zuidong, the most used site in our study area for Great Knots Calidris tenuirostris, the highest count there was on 6 May of 7,350. This is considerably lower than the count in 2019 on 8 May of 12,971. The count in 2019 was the highest number we have recorded in the eleven years of complete survey periods for this species. So, it is possible that both Red and Great Knots were at Luannan in smaller numbers this year.

We recorded 1,169 marked shorebirds from throughout the East Asian-Australasian Flyway (EAAF). Due to the shorter time and relatively inexperienced team this is, as expected, a much lower total than that of previous years. This year, 193 birds were individually recognisable from the GFN colour-banding project in Northwest Australia (NWA). While this is also lower than in years with greater effort, it is a particularly good sample and testament to the hard work of the 2020 team.  The totals were dominated, as always, by Red Knot with 189 individuals identified, Great Knot with 3 and Bar- tailed Godwit Limosa lapponica with 1. These results come from ‘scanning’ – this is systematically searching through feeding or roosting birds using telescopes and looking specifically for flags and colour- bands on bird legs. Each marked bird is recorded, and the records sent to each banding project at the end of the fieldwork season. This season, due to the water levels in the pond habitat being deeper than in all previous years, Red Knots did little feeding there and subsequently spent more time on the mudflats. Re-sighting observations and counts are easier and more productive in terms of recording marked birds on the mudflats. Despite the shorter study period and subsequently lower numbers, as in previous years, these records reflect the vital importance of the area for Red Knots from NWA and throughout the EAAF.

At high tide, when the mudflats are inundated by the sea, the ponds within the salt works/aquaculture areas host all the migrant shorebirds, making the area a critical component of the Luannan Coast. For their roosting opportunities alone, the ponds should be included in any conservation initiatives. These ponds are also an important contributing factor to the local economy and jobs. The importance of the vast area of commercial ponds adjacent to the inter-tidal area for shorebirds has been well documented from our work and that of Beijing Normal University (BNU) in previous years. This year the use of ponds by shorebirds was similar to 2019, which had much reduced use than in any previous year. Many species usually utilise the ponds, but all except two of the ponds that were explored had deep water in them consistently throughout the season. The main pond we used for scanning in 2017 to 2019 now has high water levels. This was not a surprise as we had talked in 2019, via our driver Mr. Liu, to a pond manager who had told us this pond would be filled with water for aquaculture. We do not know if the loss of all these ponds as foraging habitat is detrimental to the shorebirds fattening up at the Luannan coast to the extent that it deprives them of resources required to put on enough weight for successful migration and breeding. Nevertheless, our observations show that the loss of shallow ponds is depriving birds of foraging opportunities. In 2013, when there were many and varied ponds available to birds, we had the amazing sight of 95,833 mixed shorebird species foraging in a single pond on 16 May. On 29 May that year, we had a count of 34,200 Red Knot foraging in a shallow pond. The deep water provides few foraging opportunities particularly for the small and medium-sized shorebirds.

A table of species recorded in internationally important numbers has been compiled from GFN and BNU studies over the previous 11 northward migration seasons (2010–2020). It is an effective way to give an indication of the immense importance of the Luannan Coast Shorebird Site. In the last six seasons, seventeen species of migratory shorebirds and one migratory tern have been recorded in internationally significant numbers (1% Ramsar criteria). Five species have an absolute minimum of 10% of their entire EAAF population passing through the Luannan Coast site during northward migration (Table 4, main report). Note that these are single peak counts and do not account for turnover rate: if that statistic was applied, the total number of birds assessed using the Luannan Coast during the northward migration season would be much greater.

On the Luannan Coast the direct destruction of the intertidal habitat has slowed during the last nine years. The pressures on the intertidal areas appear to be less severe in terms of direct destruction but are still present with the development of industry and housing areas adjacent to and on previously reclaimed mudflats. There are building projects that are taking place in former pond habitat and mudflat areas reclaimed in recent years. This includes a large steel works that will have a port developed on still existing intertidal flats. Currently, multi-billion-yuan projects are in the planning stages for development within the Luannan Coast area and the future of these critically important intertidal areas remain under threat despite the commencement of management actions at the Luannan Coast by the Luannan County Government.

Global Flyway Network aims to continue conducting research activities and follow-up analysis to document the futures of four shorebird species (Bar- and Black- tailed Godwit and Red and Great Knot) at their non- breeding sites in NWA and throughout the EAAF, with an emphasis on the Luannan Coast, Bohai Bay. A critical question is the interpretation of the variable use of the Luannan Coast by Red and Great Knots. What does this variability mean? Is it due to changes to, or loss of, habitat elsewhere? Or that the favoured food of Red Knots, Potamocorbula laevis is not in regular or consistent abundance at all sites and Red Knots ‘choose’ the best sites year on year? Knowing this distinction is critical, but requires local and flyway-wide research efforts, including the continuation of satellite tracking of individual knots.

Figure 1. Interpreted satellite image of northern Bohai Bay, China with the coastal study sites marked in yellow

Full Global Flyways Network Bohai Report 2020 in PDF format