The wading bird communities of four major habitat zones are described. Shore habitats support few breeding birds but hold significant numbers of migrant and wintering waders. Oystercatcher, ringed plover, bar-tailed godwit and dunlin are the most numerous species on the sand flats; the Atlantic beaches are particularly important to turnstones, purple sandpipers and sanderling. The wintering sanderling population is of national significance. Densities of breeding waders on the machair are greater than elsewhere in Britain. The dominant species are oystercatcher, ringed plover, lapwing and dunlin. The machair is nationally outstanding for breeding ringed plovers and the Outer Hebrides supports 14% of the British and Irish population. The machair is also unique in Britain for its concentration of coastal breeding dunlin. At other times of the year flocks of lapwings, golden plovers and curlew feed on the machair. Rough grazing (blackland) inland from the machair supports high densities of breeding snipe and redshank. Large numbers of grassland plovers and snipe feed here in winter. Seven species breed on the uplands and peatlands: golden plover, snipe, curlew, whimbrel, common sandpiper, greenshank and dunlin. Most of these species are more abundant north of the Sound of Harris and the north Lewis moors hold relatively high densities of golden plovers and dunlin.