Photo of the shallow-drifting boats anchored for shorebirds surveys during the low tide in the Gulf of Mottama in January 2025

Author: Pyae Phyo Aung, Thura Soe Min Htike,Saw Moses, Gideon Dun,
Ye Min Aung, Nyan Lin, Shein Thu Lwin, Nang Phyu Phwe

Report: Link

The Gulf of Mottama (GoM), one of Myanmar’s eight Flyway Network Sites and designated as a Ramsar Site since 2017, is a crucial habitat supporting a wide variety of biodiversity, including marine mammals, fish, invertebrates, and up to 150,000 migratory waterbirds during the non-breeding season. Notably, it hosts 12 globally threatened bird species, including an estimated 60% of the critically endangered Spoon-billed Sandpiper’s global population. This area also supports the livelihoods of thousands of people by providing fish for local and regional consumption.

The Spoon-billed Sandpiper – SBS (Calidris pygmaea) is a long-distance migrant, breeding on the coastal tundra of far eastern Russia and migrating 8,000 km south along the East Asian–Australasian Flyway, including key stops in the Yellow Sea. This species winters on intertidal mudflats in South and Southeast Asia, particularly in Myanmar, China, and Bangladesh. It is classified as Critically Endangered on the IUCN Red List. In 2010, the global population was estimated to be declining by 26% annually, with about 100 pairs remaining (Zoeckler et al. 2010). Recent estimates suggest a global population of 661-718 individuals of all age classes (Clark et al. 2018) and 490 mature individuals (95% CI: 360–620) (Green et al. 2024). Its long-term population trends indicate a decline at an average rate of 5% per year (Green et al., 2024), highlighting the ongoing conservation challenges for this species. While the largest wintering population during the last decade was known to be in the northern GoM, surveys from 2009 to 2020 recorded a dramatic decline, with wintering numbers dropping from 224 individuals in 2009 to just 112 in 2020, with a further decline to 80 individuals in 2022 and 34 in 2024 (Aung et al. 2024, unpublished NCS reports).There is no specific answer to the main cause of this decline and it needs longer monitoring period to confirm the scale of decline and to learn more about the wintering pattern and monthly population status and its threats. Monitoring the wintering population of SBS is critical to understanding their population trends and supporting global population estimates. This research is a part of the annual monitoring on the wintering population of Spoon-billed Sandpipers and other threatened species in GoM and identify potential threats in collaboration with the local community.

Monthly population surveys in November-December 2024 and January-February 2025 recorded a total of 83,816 wetland-dependent birds of 41 species. Moreover, 333 individuals of seven terrestrial species including two migratory bird species; Critically Endangered, Yellow-breasted Bunting and Least Concerned Chestnut- eared Bunting were also recorded. Notably, the survey identified 62 individuals of SBS, alongside other globally threatened species, including 12 Great Knots (EN), 21 Nordmann’s Greenshanks (EN), 5,805 Curlew Sandpipers(VU), 2,159 Broad-billed Sandpipers (VU) and 48 Grey Plovers (VU). Furthermore, six Near Threatened species as Black-tailed Godwit, Eurasian Curlew, Ruddy Turnstone, Dunlin, Black-headed Ibis and Red-necked Stint (NT)/Little Stint (LC) were also recorded. Some threatened as Steppe Eagle (EN), Greater Spotted Eagle (EN), and Near Threatened species as Bar-tailed Godwit, Asiatic Dowitcher, Red Knot and Painted Stork were not found this year although 1-30 individuals of those species were recorded a few years ago. This might be because our surveyed areas cover the lower altitudinal part of the gulf while those species are common at the upper parts, more muddy areas closed to then tall salt marsh.

Among wader species, the most abundant species are Lesser Sand Plover (27,745 individuals), Kentish Plover (9,723 individuals) and Little Stint/Red-necked Stint (9,547 individuals). And the least common species are Temminck’s Stint (one individual), Ruddy Turnstone (one individual), Dunlin (two individuals) and Ruff (four individuals) respectively. Flagged birds observed include four SBS and two Curlew Sandpipers. Among the four SBS, one has a white flag on the right leg (tagged in head-starting program in Russia), two have lime flags on the right leg (tagged in the wild), and the color of the remaining SBS’s flag could not be identified. For the two CSP, one has a green over white flag on the right leg, indicating it was tagged in Singapore, while the other has a blue over black flag on the right leg, indicating it was tagged in Hainan-Guangxi, China.

Based on the proportion within 280 flocks of 8 small wader species, total wintering population of SBS was estimated as 56 individuals with 52 actually observed individuals and four additional estimated individuals. Mark-resighting analysis revealed the total wintering population as 62 individuals based on four sightings on four different flagged birds and 58 sightings on unflagged birds. Over the past 17 years (2009–2025), the observed and estimated numbers of SBS in the GoM have fluctuated significantly. The observed numbers represent the actual counts recorded during surveys, while the estimated numbers are derived by adding additional estimate according to the proportion from the extrapolated flock counts. In 2025, 52 SBS were directly observed, marking a sharp increase from the 19 individuals recorded in 2022. This is the highest number recorded in the GoM since 2020, but the trend was significantly declined over the past decade (Figure 1).

Over the past eight years (2018–2025), our consecutive surveys have primarily focused on the feeding grounds within the intertidal mudflats at the core area of the upper GoM. Despite the significant declining trend in the population of all shorebird species, it is still unclear when fluctuation is going on and challenging to have the better estimate. Identifying roosting sites during high tide remains challenging but is essential for improving population estimates and ensuring the protection of these critical areas from disturbances. Expanding surveys beyond the core area to include other potential sites along the Myanmar coast would provide a more comprehensive understanding of the wintering status of SBS and other important migratory species in the region.

Figure 1. Spoon-billed Sandpiper population estimates in the GoM from 2009-2025