Behaviour This species is a fully migratory circumpolar breeder with several sub-populations that employ a number of migration strategies, from short coastal flights to long, non-stop flights overland on a broad front (del Hoyo et al. 1996). The sub-population that breeds in north-east Greenland migrates through Iceland, Britain and western France to arrive in its West African wintering grounds (specifically Banc d'Arguin in Mauritania) from late-July, returning again between March and early-April (del Hoyo et al. 1996). European birds may gather in large congregations from the beginning of July in areas such as the Wadden Sea or the Wash to moult (del Hoyo et al. 1996), and some juveniles may remain in the non-breeding range all year (del Hoyo et al. 1996). The species breeds dispersed or aggregated in loose colonies, and travels in group sizes of up to 1,500 on passage, remaining in large groups (up to hundreds of thousands of birds) throughout the non-breeding season (Cramp and Simmons 1977, del Hoyo et al. 1996). The species is active both diurnally and nocturnally (Cramp and Simmons 1977, del Hoyo et al. 1996, Shepherd and Lank 2004). Habitat Breeding In the breeding season this species frequents moist boggy ground interspersed with surface water, such as tussock tundra and peat-hummock tundra in the arctic, as well as wet coastal grasslands, salt marshes and wet upland moorland (Cramp and Simmons 1977, del Hoyo et al. 1996). Non-breeding In the non-breeding season this species mainly prefer estuarine mudflats, but also frequent a wide variety of freshwater and brackish wetlands (Cramp and Simmons 1977, del Hoyo et al. 1996), both coastal and inland, including lagoons, muddy freshwater shores, tidal rivers, flooded fields, sewage farms, salt-works, sandy coasts (Cramp and Simmons 1977, del Hoyo et al. 1996), lakes and dams (Hockey et al. 2005). For roosting during high tides and at night this species prefers large fields of naturally fertilised short pasture or soil-based crops with few vertical structures that could be used by predators (Shepherd and Lank 2004). Diet Breeding This species is omnivorous during the breeding season, consuming mostly adult and larval insects (dipteran flies, beetles, caddisflies, wasps, sawflies and mayflies), and also spiders, mites, earthworms, snails, slugs and plant matter (usually seeds) (Cramp and Simmons 1977, del Hoyo et al. 1996). Non-breeding It is also omnivorous during the non-breeding season, consuming mostly polychaete worms and small gastropods, as well as insects (dipteran flies and beetles), crustaceans, bivalves, plant matter and occasionally small fish (Cramp and Simmons 1977, del Hoyo et al. 1996). Breeding site Its nest is a scrape or shallow depression in the ground, concealed in vegetation and sometimes in a tuft or tussock (and thus raised slightly off the ground) (Cramp and Simmons 1977, del Hoyo et al. 1996). Management information The provision of well-surfaced paths in breeding areas that receive > 30 visitors a day has been shown to reduce the impact of human disturbance on this species' reproductive performance (Pearce-Higgins et al. 2007). It is also known to show increased hatching successes when ground predators have been excluded by erecting protective fences around nesting areas (Jackson 2001).

Breeds from northern Alaska (USA) and northern Canada east to south-west Baffin Island. Breeds in south-east Greenland, Iceland, the Faroe Islands and northern Europe , east throughout much of Siberia to the northern Sakhalin and Kuril Islands. Birds move south for the winter, chiefly to coastlines in southern North America and northern Central America, Western Europe, north and west Africa, the Arabian Peninsula, South Asia and East Asia.

Conservation Actions Underway
This species is covered by the general protection regime provided by Article 1 of the European Union (EU) Birds Directive to all naturally occurring wild species in the EU. It is listed on Annex II (strictly protected) of the pan-European Bern Convention, Annex II of the Convention on Migratory Species (CMS) and Annex II of the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA). Across the EU, 762 Natura 2000 sites have been designated for the conservation of this species (EEA 2024). The subspecies C. a. schinzii is listed on Annex I (special protection) of the Birds Directive, and is also listed by the Helsinki Convention (HELCOM) as a taxon that that is threatened and/or declining in the Baltic Sea. C. a. schinzii is included on the list of priority EU species that can benefit from a higher EU co-funding rate (up to 75%) under the LIFE Programme; to date (June 2024), the LIFE project database lists nine projects that have taken practical conservation measures for this subspecies, mainly in the Baltic at some of the 73 Natura 2000 sites designated for the conservation of this taxon. 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 C. alpina) 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 South-East Asian countries: Mongolia, China, Bangladesh, Viet Nam, Cambodia, Lao PDR, Philippines, Thailand, Malaysia and Indonesia, all of which are used by C. alpina on northbound and southbound migrations between breeding and wintering areas, and many also for wintering. 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 organizations, communities, regional organisations like the East Asian-Australasian Flyway Partnership. A large portion of this species' breeding population is covered by PRISM surveys in North America, enabling regular monitoring.

Conservation Actions Proposed
Ensure population monitoring continues throughout and its range, and preferably expand it to other regions (particularly in East Asia and wintering grounds in Africa where data coverage is currently patchy). In the East Asian-Australasian Flyway, the main action needed for this is the amelioration of threats on its migration. 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. Many of these threats, particularly development of coastal wetlands, apply also to the Arabian Peninsula where there is a need for sensible policy-making and implementation to reduce illegal killing and habitat loss (Brochet et al. 2016, de Fouw et al. 2018).