Spoon-billed Sandpipers: Track and Trace

The cutest wader in the world has to be the ‘critically endangered’ Spoon-billed Sandpiper, a tiny wader with an ice-cream spoon for a bill. An ever-reducing number of pairs breed in the coastal tundra of north-east Russia. They migrate to south-east Asia, spending the winter months anywhere between China and Bangladesh.

During autumn there are sightings of moulting Spoon-billed Sandpipers around the mudflats of the Yellow Sea (People’s Republic of China, Democratic People’s Republic of Korea (DPRK) and Republic of Korea). Where else do Spoon-billed Sandpipers go? A 2020 paper shows that it is possible to trace potentially important missing sites by tracking individuals. Two 2021 papers have used data from tagged and tracked birds to update the population estimates (later in this blog) and to try to understand changes in local numbers, potentially linked to intertidal mudflats (end of this blog).

Away from their breeding areas, Spoon-billed Sandpipers are threatened by:

  • Loss of non-breeding habitats, especially intertidal mudflats, because of land-claim projects to create harbours, industry zones, wind and solar power generation farms, aquaculture ponds and rice-fields.
  • The spread of invasive Spartina species (cordgrass) across mudflats in some coastal areas of China, the Republic of Korea and Japan is reducing the available feeding area.
  • Local hunting pressure, for personal consumption and local trade.
  • Accidental losses of birds tangled in permanently set fishing nets.

There is more about these issues and efforts to reduce problems being faced by waders on the East Asian-Australasian Flyway on the Saving the Spoon-billed Sandpiper website.

Better information on the location and timing of use of stopover and wintering sites is essential if conservation measures to prevent hunting and further losses of intertidal habitat are to be applied across the species’ range. In a 2020 paper in Wader Study, Prof Qing Chang and colleagues describe in detail the post-breeding migration of adult Spoon-billed Sandpipers. For the first time, they are able to report on the timing of the migration, the duration of stay at stop-over sites, and the distances travelled between stop-overs.

Six Spoon-billed Sandpipers were caught in Chukotka

The research team captured 13 adult Spoon-billed Sandpipers and fitted each bird with a solar-powered transmitter that reports the bird’s locations, via satellites. Six were caught on their nests in Chukotka and seven were netted at Tiaozini in Jiangsu Province, near Shanghai in China. The paper contains full information on the tags, which were glue-mounted to the back of the birds, and details of the data collected and the algorithms used to interpret groupings of locations. This will be of help to anyone considering using these devices.

Why use Satellite transmitters?

Information from colour-ringing and counting has produced fascinating information about Spoon-billed Sandpipers. We now know more about the breeding, migration and wintering locations of the total population, estimated at just 660** individuals in 2014, than we did in 2010, when the serious plight of the species became more widely apparent (Clark et al). There has been international support for conservation action in non-breeding hot-spots in Myanmar, Bangladesh and China, where waders are benefiting from measures designed to reduce hunting pressure and maintain feeding habitat.

** The population total has been updated since this blog was produced. Although numbers have continued to decline, the new estimate is between 569 and 978 (details at end of this blog and in this paper).

Counting waders in the Gulf of Mottomar in Myanmar

The amount of information that can be obtained from counts and colour-ring sightings is limited by knowledge of where to look for birds. There are still big questions to ask. Where do birds colour-ringed in Russia, but not yet seen, spend the winter, where are the breeding grounds for birds ringed in the winter and then not seen in the summer, and what happens to birds in the weeks when they are on migration? Geolocators or satellite transmitters might provide some answers.

Geolocators are great, but information can only be downloaded from these devices by recapturing tagged birds and there is poor precision of reports received during the equinox periods (late March and late September), when daylength doesn’t change with latitude and many waders are on the move. Additionally, given the tiny size of the population and the mobility of breeding birds, recapturing birds to remove geolocators is unlikely to be as easy as it has been for many other wader species. Finally, as has been discussed in a previous WaderTales blog, geolocators can have unanticipated negative consequences for small calidrid sandpipers.

Health & Safety

Every Spoon-billed Sandpiper is precious, so safety is of paramount importance in tagging studies. Prior to deployment on Spoon-billed Sandpipers, tags of the same weight and dimensions were trialled on ‘surrogate’ birds – a small flock of twelve captive-reared Dunlin. The health of these birds was monitored in an aviary and birds seemed to behave normally. Would the same be true for similarly-sized Spoon-billed Sandpipers that migrate thousands of kilometres? Imagine the relief when the first tagged wild bird took off a few days after tagging and started to reveal unique insights into the species’ migration!

From Russia with tags

The six adults captured on the nest and tagged in subarctic Chukotka, Russia, left in July and moved west and south through Kamchatka in July and early August. This was followed by long flights (>1,000 km) across the Sea of Okhotsk to Sakhalin Island. By this stage, only four of the tags were still functioning but these birds provided some fascinating information:

  • All four birds used the same area (Tyk Bay) on the western side of Sakhalin Island. They stayed for long periods and all flew long distances when they left – which means that this site and the resources it provides are really important!
  • The next leg of the journey took the birds further south to sites within Russia and to the Democratic People’s Republic of Korea. All four ended up in DPRK.
  • Two birds stayed long enough to moult close to the Demilitarised Zone in the DPRK but the other two moved on and spent a month moulting at two different sites in Jiangsu Province, China.
  • By this point, in the late autumn, it is believed that all four birds had moulted. Given the method of tag attachment, it was thought that birds would drop their tags during moult, but one bird (L07) continued to transmit data.
  • The four individuals that were tracked between the breeding area and their presumed moulting sites stopped for 2 days or more at between 3 and 7 sites.

Post-moult migration

Seven birds were tagged in Tiaozini in Jiangsu Province. With L07 still transmitting, that meant that there were eight birds to track during the next stage of the migration season. Would they be able to trace missing sites that could potentially be protected.

  • All eight of these birds moved west and south in October or early November.
  • Three birds moved to separate sites in southern China, where they remained until their tags ceased to provide data.
  • Five birds visited stopover sites in China before moving on to their wintering areas in Vietnam, Myanmar, Sumatra and Bangladesh. Sumatra is outside the previously-known wintering range.
  • One of the birds that flew to Bangladesh stopped in Vietnam and Myanmar, while the other one stopped in the Gulf of Thailand. It then overflew Malaysia, Myanmar and the Bay of Bengal before transmissions ceased just before arrival in Bangladesh.
  • The eight individuals that were tracked between moulting and wintering grounds trace out a vast coastline (figure) – illustrating the conservation challenges of trying to save the Spoon-billed Sandpiper. Only two of the birds finished up at well-known sites that are covered regularly by winter counts.

Identifying sites of conservation importance

With only thirteen tagged birds providing four links between breeding and moulting areas and eight links between moulting and wintering areas, the research team have greatly increased our understanding of how it might be possible to protect Spoon-billed Sandpipers. As the authors point out in their Discussion, however, the “list of stopover sites is not comprehensive because of the small number of birds tagged and the duration of stay criterion we used”. Seventeen sites were visited by only one bird and other sites where Spoon-billed Sandpipers are regularly seen were not visited by any of the tagged birds. This suggests that there are probably other important sites that are yet to be traced. The authors suggest some of the limitations created by sampling. The key findings are:

  • During the post-breeding migration, several sites appeared to be of special importance. Seven stop-over sites were used for long periods or were used by birds immediately before long flights (or both).
  • Tyk Bay (Sakhalin, Russia) and Ryongmae Mudflat (DPRK) were used as stopovers by all the tagged birds that passed beyond these sites. Neither site was previously thought to be important for Spoon-billed Sandpipers.
  • The post-breeding moult period is an energetically expensive stage of a wader’s annual cycle. For Spoon-billed Sandpipers, Ryongmae Mudflat (DPRK), Tiaozini (China) and Yangkou (China) are of special importance in this regard (Green et al. 2018, Chang et al. 2019, Yang et al. 2020).
  • Most of the sites in which tagged birds spent the winter months had not previously been visited by count teams. Subsequent visits to some of these previously unknown sites in China added counts of 77 birds.

Once tags had fallen off, birds could still be located by their leg-flags if they were seen by teams of observers who visited known moulting, stop-over and wintering locations. Seven of the birds that carried transmitters have been seen in subsequent years at similar times and places. This suggests that birds are site-faithful between years, implying that a site that is identified to be of importance is really important – birds are not randomly choosing mudflats on a whim.

Yellow 57 – also known as Y57

The stopover-site clusters of registrations were all located on or near coasts, except for one, used briefly, on sandbanks in the Irrawaddy River, Myanmar. Most clusters included areas of intertidal mudflats, especially on estuaries. However, a few included other habitats, such as saltpans and fishponds in impounded areas which had previously been intertidal. Ten of the 28 clusters have some protection under national legislation or international agreements, a further eleven clusters are recognised as Key Biodiversity Areas and/or East Asian-Australasian Flyway Network Sites, but seven clusters appear to have neither protection nor international recognition.

The lack of protection of wintering sites is of concern because of continuing threats to Spoon-billed Sandpipers and their habitats. Hunting of Spoon-billed Sandpipers remains a problem, for instance. This is illustrated by a story from the paper.

During a visit to site Guankoudu (Fujian Province, China) in December 2016, occasioned by the tracking of one of the tagged birds, many mist-nets, more than 2 km in total length, were found, some of which held entangled live and dead shorebirds. This site has no legal protection, but this illegal bird-trapping was reported to local government agencies, whose staff quickly began the removal and destruction of the nets.

If sites are identified, protection is possible.

There may be a Spoon-billed Sandpiper in this cloud of waders over the Taiozini Mudflat

Background to this work on Spoon-billed Sandpipers

The Spoon-billed Sandpiper conservation programme, which includes research, site protection, conservation breeding and head-starting, is a collaboration between the Wildlife & Wetlands Trust (WWT), Birds Russia, Moscow Zoo and the RSPB, working with colleagues from the BTO, BirdLife International, ArcCona, Nanjing Normal University, Spoon-billed Sandpiper in China, Hong Kong Waterbirds Ringing Group, Microwave Telemetry and the Spoon-Billed Sandpiper Task Force.

The project is supported by WWT, RSPB, the UK Government’s Darwin Initiative and SOS – Save our Species, with additional financial contributions and support from BirdLife International, the East-Asian Australasian Flyway Partnership, the Convention on Migratory Species, Heritage Expeditions, the Australasian Wader Study Group of Birds Australia, the BBC Wildlife Fund, Avios, the Olive Herbert Charitable Trust, the Oriental Bird Club, British Airways Communities & Conservation Scheme, New Zealand Department of Conservation, the Queensland Wader Study Group, New South Wales Wader Study Group, Chester Zoo, Wader Quest, Dutch Birding, OSME and British Birds Charitable Trust and many generous individuals. Leica Camera AG is WWT’s exclusive optic partner for this key conservation project.

An assessment of the conservation status of the species can be found on the BirdLife International site:

To read more about the project to set up a captive breeding population and head-start Spoon-billed Sandpiper chicks in their Russian breeding grounds visit the Saving Spoon-billed Sandpiper website.

There is lots of information on the conservation action to protect the species on the Saving the Spoonbill Sandpiper website and on the East Asian-Australasian Flyway Partnership Website. Here’s one example.

Many wader species on the East Asian-Australasian Flyway are threatened by habitat loss, as discussed in this WaderTales blog.

Paper in Wader Study

Post-breeding migration of adult Spoon-billed Sandpipers Qing Chang, Evgeny E. Syroechkovskiy, Guy Q.A. Anderson, Pyae-Phyo Aung, Alison E. Beresford, Kane Brides, Sayam U. Chowdhury, Nigel A. Clark, Jacquie A. Clark, Paul Howey, Baz Hughes, Paul Insua-Cao, Yifei Jia, Elena Lappo, Katherine K.S. Leung, Egor Y. Loktionov, Jonathan Martinez, David S. Melville, James Phillips, Chairunas Adha Putra, Pavel S. Tomkovich, Ewan Weston, Jenny Weston, Nikolay Yakushev & Rhys E. Green. Wader Study 127(3): doi:10.18194/ws.00201

UPDATE: How many Spoon-billed Sandpipers?

As discussed above, Nigel Clark, Rhys Green and colleagues previously estimated the world population of adult Spoon-billed Sandpipers at 420-456 individuals, based upon counts and sightings of individually-marked birds at a staging area on the Jiangsu coast of China. Adding in juveniles, produced an estimated population of 661-718. (Clark et al)

In a 2021 paper in Wader Study, Rhys Green and colleagues have used ten similar counts and scan samples of marked birds from China, Myanmar and Bangladesh, conducted during the period 2014-2019, to produce an updated estimate of 490 breeding-age adults (95% CL = 360-620). Adding in immature birds increases the total to 773 individuals of all ages (95% CL = 569-978). The 2021 estimate is similar to the previous one but increased geographical coverage and a larger number of surveys confer a higher level of confidence in its precision.

From the trend in the ten estimates during the period 2014-2019, it looks as if the world population of breeding adults has continued to decline at about 8% per year. This estimate of trend is not very precise but its rate is of similar magnitude to the 9% per year obtained using repeat wintering surveys in Myanmar (2009–2016). This apparent decline is less drastic than the estimated rate of loss in the period up to 2008, when there was a 26% per annum drop in the number of adult pairs across a sample of sites in the breeding grounds.

The possible slow-down in the rate of decline follows huge efforts to protect key wintering areas and staging sites, and a head-starting programme that has seen 206 chicks reared and released in the Meinypil’gyno area (2012-2020). Spoon-billed Sandpipers still seem to be heading towards extinction, but not as quickly. This emphasises the importance of finding and then increasing the protection of more staging and wintering sites, as identified in the tracking paper (see above).

UPDATE: Rapid fall in Bangladesh numbers

Sayam Chowdhury, Mohammed Foysal & Rhys Green have analysed count data for Spoon-billed Sandpipers wintering at Sonadia Island, Chattogram Division, Bangladesh, in the period 2012/13 to 2020/2021, and have presented their results in the Journal of Ornithology.

Sadly, they found that numbers declined at a mean rate of 9.5% per year during the period 2012/2013 to 2017/2018 but at 49.1% per year during 2018/2019 to 2020/2021. Count estimates for other species in each winter showed no decline during the 9-year period, which suggests that the decline in the local population of the Spoon-billed Sandpiper was not related to local factors. The period analysed in this paper includes recent years that were not included in the 2021 Wader Study paper.

The authors recommended an immediate reassessment of threats faced by the Spoon-billed Sandpiper and improved conservation interventions. In this context, it is concerning that no head-starting is taking place in Meinypil’gyno in 2022.

UPDATE: Using local tracking information

Although tracking was primarily used to reveal the flyway-scale migratory movements of Spoon-billed Sandpipers, the finer detail of how individuals move around estuaries has proved useful too, as revealed in a 2021 paper in Wader Study about the intertidal areas of Jiangsu province in China, particularly the key site of Tiaozini. Research led by Prof Qing Chang has shown that declines in autumn numbers at Tiaozini between 2017 and 2020 appear to be associated with changes to the intertidal mudflats and positions of major channels.

Tiaozini, recently designated as part of a UNESCO World Heritage Site, is particularly important to Spoon-billed Sandpipers. An estimate of 225 birds, made in autumn 2017, represented 46% of the world population of the species and the fact that this dropped to 151 by 2020 is worrying. Most of the decline happened between 2018 and 2019. What had caused this change to numbers in a key moulting area?

To identify parts of the intertidal area used by Spoon-billed Sandpipers, the research team mapped locations of satellite-tagged birds in Tiaozini in 2017 and 2019. Data from seven tagged birds indicated that Spoon-billed Sandpipers moved to intertidal flats up to 7 km out from the seawall to feed at low tide, way beyond the limits of land-based observations. The team analysed satellite imagery and found that the extent of exposed mudflats appeared to have declined by about 20% between 2017 and 2020. The abrupt reduction in the local population of Spoon-billed Sandpipers at Tiaozini is of concern because surveys of the two closest sites which are known to support Spoon-billed Sandpipers, at Yangkou and Dongling, suggested no significant displacement of birds from Tiaozini.

It is interesting that a few tagged individuals might help to explain large-scale changes to the wader assemblage on an estuary, simply by pinpointing critical feeding areas. Although protected now, Tiaozini and other parts of Jiangsu province have seen huge changes over recent decades, with coastal land-claims and new sea walls. These may still be affecting the way that sediments form and flow within the mudflats.

The paper demonstrates the importance of securing more (and bigger) protected coastal wetlands, to provide opportunities for migratory shorebirds to adapt to change. Thankfully the Yangcheng World Heritage Site that includes Tiaozini is big and stands a good chance of being able to encompass future local Spoon-billed Sandpiper distribution change. The authors of this study stress that Yancheng-Tiaozini remains of critical importance to moulting Spoon-billed Sandpipers that will winter as far away as Banglasdesh.

WaderTales blogs are written by Graham Appleton (@GrahamFAppleton) to celebrate waders and wader research. Many of the articles are based on published papers, with the aim of making shorebird science available to a broader audience.