Grey Wagtail

The grey wagtail (Motacilla cinerea) is a long-tailed wagtail breeding across much of Europe and Asia. Adults are about 17–20 cm long and weigh around 18 g. The upperparts are mostly slate-grey, contrasting with a bright yellow vent and yellow underparts that become more extensive in breeding plumage. A pale supercilium is usually obvious. Breeding males develop a black throat, while females generally have a paler or mottled throat. The species characteristically bobs its long tail as it moves and feeds along the water's edge.

The combination of grey upperparts, yellow underparts and an exceptionally long tail separates the species from the western yellow wagtail (Motacilla flava) and other yellow wagtails, which are usually greener or more yellow above and favour open wet grassland rather than fast-flowing streams.

Grey wagtails are strongly associated with running water, especially streams and rivers with exposed stones, gravel, riffles, small waterfalls and nearby banks or structures that provide nesting sites. They also use slower rivers, lakes, ponds and urban waterways, particularly outside the breeding season.

A 2024 study of 203 breeding territories in the Beskid Żywiecki Mountains of southern Poland found grey wagtails more often along stream sections with gentler gradients. Such sections can hold larger volumes of water and provide good conditions for aquatic invertebrates. The birds showed no strong preference for one surrounding forest type, suggesting that the structure of the watercourse itself is more important than the type of woodland around it.

The diet consists mainly of small invertebrates. Aquatic insects and their larvae are especially important, together with flies, beetles and other terrestrial prey. Birds run over stones and margins, pick prey from the water surface and vegetation and make short aerial sallies after flying insects.

Studies at British streams have shown that feeding varies with both prey availability and the structure of the riparian zone. Grey wagtails also take terrestrial insects beside the stream and can rely more on them when aquatic prey becomes less abundant.

The species is partially migratory. Many birds in western and southern Europe are resident or make only short movements, while populations breeding farther north and east move south in autumn. Wintering birds occur widely across western and southern Europe, North Africa and southern Asia.

Movements are strongly influenced by ice and access to flowing water. Birds may leave inland territories when streams freeze and shift to larger rivers, springs, coasts or urban waterways that remain ice-free. Return to northern breeding areas begins early in spring as waterways open again.

Grey wagtails nest in sheltered cavities close to running water. Natural sites include holes in banks, rock faces and among tree roots, while bridges, retaining walls, buildings and other human structures are frequently used. The nest is a compact cup of grass, roots and moss lined with finer material.

A typical clutch contains about five eggs. The female performs most of the incubation for roughly 12–13 days, and both parents feed the chicks. The young usually leave the nest after about 14–15 days. Two broods are common in favourable areas and a third may occasionally be attempted.

The grey wagtail is classified as least concern on the IUCN Red List and remains widespread across a very large Eurasian range.

Regional trends are mixed. Long-term monitoring in the UK indicates a broadly stable population over 1995–2024, although a marked decline occurred after an earlier increase and the pattern varies geographically. Local breeding populations depend closely on the condition of streams, including naturally structured channels, intact banks and riparian habitat.