Numenius madagascariensis is listed as Endangered because of estimated rapid population declines over the past three generations (25 years). The main cause of these declines is thought to be widespread land reclamation on its staging grounds in East Asia, but hunting, disturbance, and habitat conversion elsewhere have also been identified as plausible threats.

This species breeds in eastern Russia, from the upper reaches of the Nizhnyaya Tunguska river east though the Verkhoyarsk mountains to Kamchatka, and south to Primorye (del Hoyo et al. 1996). Most birds apparently breed in the far south-east of the mapped range (see Supplementary Information: Hansen et al. 2022). The Yellow Sea region of Democratic People's Republic of Korea, Republic of Korea and China is a particularly important stopover site on northward and southward migration. It has been recorded as a passage migrant in Japan, Brunei, Bangladesh, Thailand, Viet Nam, Philippines, Malaysia and Singapore, with up to 75% of the population wintering in Australia (Lilleyman et al. 2021). The remaining proportion of the population winters in China, Indonesia, Papua New Guinea, and New Zealand (del Hoyo et al. 1996).

Attempts to be estimate the population size of this species have generally been consistent. Wetlands International (2015) estimated 32,000 birds, while Bamford et al. (2008) estimated 38,000. Using two different methods, Hansen et al. (2022) got ostensibly similar results. Using a method of spatial extrapolation (SE) on non-breeding range count data, the latter authors calculated 33,840 birds; however, not all of these will be mature birds capable of breeding. In another method, Hansen et al. (2022) combined the species' breeding range and density (BRD) to calculate a population size of 34,862, all of which are likely to be breeding individuals. The authors concluded a rounded population estimate of 35,000, accepting a preference for the data derived from the SE method. If 0.6-0.8 of birds in this estimate were mature, this would suggest a population size of c.21,000-28,000 mature individuals, significantly below the number calculated using the BRD method (c.35,000 mature individuals). To account for uncertainty, the global population size is set to 20,000-35,000, with a best estimate of 21,000-28,000.

The species breeds on open mossy or transitional bogs, moss-lichen bogs and wet meadows, and on the swampy shores of small lakes; in the non-breeding season it is essentially coastal, occurring at estuaries, mangrove swamps, saltmarshes and intertidal flats, particularly those with extensive seagrass (Zosteraceae) meadows. It often roosts in salt-marshes, behind mangroves, or on sandy beaches (del Hoyo et al. 1996). As well as tidal flats, salt-pans in the Inner Gulf of Thailand provide important roosting and feeding sites for overwintering shorebirds such as N. madagascariensis (Sripanomyom et al. 2011). Its diet on breeding grounds includes insects, such as larvae of beetles and flies, and amphipods. Berries are also consumed during the autumn migration. In non-breeding areas it feeds on marine invertebrates, preferentially taking crabs and small molluscs but also feeding on other crustaceans and polychaete worms (del Hoyo et al. 1996). This migratory wader nests from early May to late June, often in small colonies of 2-3 pairs, with an average clutch size of four eggs. It probably delays maturity longer than most shorebirds, perhaps not breeding until 3-4 years old (del Hoyo et al. 1996, Rogers 2006).

The main threats to this species occur on its migration route down the Yellow and East China Seas, where habitat loss and hunting are significant threats. The extent of reclaimed land along the Yellow Sea coastline now exceeds the extent of remaining intertidal mudflat (Murray et al. 2014, IUCN 2023), suggesting that this may have contributed greatly to declines in this species. The rate of habitat lost to land reclamation has slowed since a peak in c. 2013, in particular in recent years due to the promised near-ceasing of land reclamation in China in early 2018 (Melville 2018); however, recent satellite data suggests that the extent of intertidal mudflat has continued to decrease, in large part due to continued reclamations in the Korean Peninsula (IUCN 2023). Mudflats have also continued to degrade in suitability for this species and other shorebirds because of the invasive alien Spartina alterniflora cordgrass, which appears to be spreading; in recent (post 2020) years, this threat has probably driven greater declines than planned land reclamation. In addition to land reclamation, coastal development and a rapid increase in the human population along the coastline of the Yellow Sea has led to widespread degradation of mudflats and coastal habitats used by this species; IUCN (2023) (and references therein) cite the following as additional drivers of mudflat loss and degradation: 'processes such as changes in sediment supply, loss of coastal vegetation associated with development...erosion, redistribution of sediments due to storms, and compaction and subsidence (sinking) caused by subsurface resource and groundwater extraction are also likely to be factors'. Offshore windfarms may have a so far unquantified impact on birds due to collisions (unlikely) and displacement and disturbance of feeding birds (more likely). Disturbance on mudflats by fishermen and others using the mudflats may also be reasonably considered a threat. Hunting is also possibly a significant threat impacting this and other shorebird species on passage (Gallo-Cajiao et al. 2020) and on this species' breeding grounds (Klokov et al. 2023). In Australia, only sea-level rise and disturbance from dogs have been identified as threats (Lilleyman et al. 2021). The discharge of toxic pollutants into coastal wetlands may also be a threat.

Climate change has been identified for several shorebird species as a threat that is driving reduced breeding productivity by a number of mechanisms (e.g. Meltofte et al. 2007, Eikelenboom 2016, Kubelka et al. 2018); more research for this species specifically is needed.

Hunting is a probable threat to this species, as the hunting of shorebirds across the East Asian-Australasian Flyway is not uncommon (see, e.g., Gallo-Cajiao et al. 2020, Yong et al. 2022), including on the species' breeding grounds (Klokov et al. 2023).

Conservation and Research Actions Underway
Listed in CMS Appendices I and II. It is federally listed as Critically Endangered in Australia due to rapid population declines. Some habitats along flyway routes are protected. Active management is also underway at some Australian sites to combat cord grass invasion, as well as protective measures implemented to reduce disturbance at roost sites. The Australasian Wader Studies Group, along with BirdLife Australia's Shorebirds 2020 Project and committed volunteers continue to monitor migratory shorebirds within the East Asian-Australasian Flyway (Vine and Maurer 2016). China is investing hundreds of millions of dollars to clear tidal mudflats of Spartina cordgrass, with the aim of eliminating 90% of it by 2025; locally, this has already been successful, for example at Chongming Dongtan National Nature Reserve (Stokstad 2023). The governments of China and South Korea have halted new projects that require or depend upon land reclamation, and across the Korean Peninsula the number of coastal wetlands has increased; moreover in China and South Korea, key areas for migratory shorebirds (including N. madagascariensis) have been identified and prioritised by government and two World Heritage nominations have been made on these grounds (IUCN 2023). Although data on scale or impact are sparse, IUCN (2023) consider that "support for coastal wetland conservation and wise-use appears to have increased over the last decade". There has been a substantial increase in the number of volunteer groups and NGOs helping to monitor the migrations of shorebirds and other waterbirds, as well as increased media coverage and special events, demonstrating enhanced awareness among coastal communities (see also EAAFP 2016). North Korea became a Party to the Ramsar Convention and joined the EAAF Partnership in 2018. In 2021, the 'Regional Flyway Initiative' (RFI) was set up by the Asian Development Bank, with technical support from BirdLife International, with the aim of protecting and restoring priority wetland ecosystems and the associated ecosystem services they provide in the East-Asian Australasian Flyway (EAAF), the most threatened flyway globally. The Initiative is slated for implementation in 10 East, South and Southeast Asian countries:  Mongolia, China, Bangladesh, Viet Nam, Cambodia, Lao PDR, Philippines, Thailand, Malaysia and Indonesia, many of which are used by N. madagascariensis on northbound and southbound migrations between breeding and wintering areas. The RFI will mobilise large-scale financing to support the protection, sustainable management and restoration of at least 50 priority wetlands across ten Asian countries, with an initial financing commitment of $3 billion from the ADB (BirdLife International 2022). Over time, the RFI aims to enhance and expand the existing efforts in conserving and managing priority wetlands identified on the basis of supporting globally significant congregations of migratory waterbirds, and leverage on collaborative opportunities with stakeholders including national governments, civil society organisations, communities, regional organisations like the East Asian-Australasian Flyway Partnership.

Conservation and Research Actions Proposed
Continue to monitor population trends. Restore reclaimed wetland sites. Campaign to stop shorebird hunting in Asian countries. Legally protect it in all range states. Survey the breeding grounds for potential threats. China needs to implement its plan to eliminate 90+% of Spartina cordgrass to prevent further loss of feeding habitat (much has already been lost to land reclamation; IUCN 2023). The discharge of toxic pollutants into coastal wetlands (especially where there are large shorebird congregations) needs to be controlled. Further degradation of mudflats needs to be stopped, including monitoring and preventing detrimental release of riverine sediments and responsible planning of offshore windfarms. Tools are available, such as AviStep (https://avistep.birdlife.org/) to ensure sustainable building of renewable energy infrastructure.