Behaviour This species is a full long-distance migrant that travels mainly via offshore and coastal routes using a number of favoured stopover sites (del Hoyo et al. 1996). It breeds from June to mid-July in solitary pairs (del Hoyo et al. 1996), departing the breeding grounds between mid-July and early-September (Hayman et al. 1986). The species usually occurs in small flocks on migration (Johnsgard 1981) although it may aggregate into larger flocks at stopover sites (Hayman et al. 1986), and in winter it forages in small to very large flocks (del Hoyo et al. 1996). Habitat Breeding The species breeds in the high Arctic on barren, stony tundra with well-drained ridges (Johnsgard 1981, del Hoyo et al. 1996), gentle slopes or level alluvial plains supporting scattered vegetation of willow Salix spp., Dryas spp. and saxifrage Saxifraga spp. usually less than 200 m above sea-level (Johnsgard 1981). Non-breeding On passage the species may occur on inland freshwater or saline lakes (del Hoyo et al. 1996) but it is largely coastal during the winter, inhabiting open sandy beaches exposed to the sea, the outer reaches of estuaries, rocky and muddy shores, mudflats (del Hoyo et al. 1996) and coral reefs (Urban et al. 1986). Diet Breeding When breeding the species takes insects (especially adult and larval Diptera, Coleoptera and Lepidoptera) as well as spiders and crustaceans (del Hoyo et al. 1996). On arrival on the breeding grounds the species may also complement its diet with plant matter (e.g. seeds, saxifrage buds, moss and algae) (del Hoyo et al. 1996) before invertebrate prey becomes available (Johnsgard 1981). Non-breeding During the winter its diet consists of small molluscs, crustaceans, polychaete worms and adult, larval and pupal insects (e.g. Diptera, Coleoptera, Lepidoptera, Hemiptera and Hymenoptera), as well as occasionally fish and carrion (del Hoyo et al. 1996). Breeding site The nest is a shallow depression on the bare earth (del Hoyo et al. 1996) of stony well-drained ridges, gentle slope or level alluvial plains (Johnsgard 1981).

Breeds on high-arctic tundra including in Arctic Canada (which hosts majority of global population), northernmost Alaska (USA), Greenland, Norway and Siberian Russia. In winter can be found in suitable habitat almost anywhere in the world!

Conservation Actions Underway
The species is listed in Annex II of CMS. It is not listed on the annexes of the European Union (EU) Birds Directive, but is covered by the general protection regime provided by Article 1 of the Directive to all naturally occurring wild species in the EU. 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. alba 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 the continuation of regular monitoring. Research threats to understand why some populations in the Americas appear to be declining rapidly.