The sanderling is a small wading bird. It is a circumpolar Arctic breeder, being among the most extreme northern breeding birds in the world, nesting only on the coldest tundra, north of the 5°C July isotherm; in Europe, its southernmost breeding locality is Svalbard, where only a handful (5–15) pairs breed. It is a long-distance migrant, wintering south to South America, western and southern Europe, Africa, and Australia. It is highly gregarious in winter, sometimes forming large flocks on coastal mudflats or sandy beaches.