UKBirds

Ruff

Philomachus pugnax

The Ruff (Philomachus pugnax) is a medium-sized wading bird that breeds in marshes and wet meadows across northern Eurasia. This highly gregarious sandpiper is migratory and sometimes forms huge flocks in its winter grounds, which include southern and western Europe, Africa, southern Asia and Australia. It is usually considered to be the only member of its genus, and the Broad-billed and Sharp-tailed Sandpipers are its closest relatives.

The Ruff is a long-necked, pot-bellied bird. This species shows marked sexual dimorphism; the male is much larger than the female (the reeve), and has a breeding plumage that includes brightly coloured head tufts, bare orange facial skin, extensive black on the breast, and the large collar of ornamental feathers that inspired this bird's English name. The female and the non-breeding male have grey-brown upperparts and mainly white underparts. Three differently plumaged types of male, including a rare form that mimics the female, use a variety of strategies to obtain mating opportunities at a lek, and the colourful head and neck feathers are erected as part of the elaborate main courting display. The female has one brood per year and lays four eggs in a well-hidden ground nest, incubating the eggs and rearing the chicks, which are mobile soon after hatching, on her own. Predators of wader chicks and eggs include mammals such as foxes, feral cats and stoats, and birds such as large gulls, corvids and skuas.

The Ruff forages in wet grassland and soft mud, probing or searching by sight for edible items. It primarily feeds on insects, especially in the breeding season, but it will consume plant material, including rice and maize, on migration and in winter. Classified as "least concern" on the IUCN Red List criteria, the global conservation concerns are relatively low because of the large numbers that breed in Scandinavia and the Arctic. However, the range in much of Europe is contracting because of land drainage, increased fertiliser use, the loss of mown or grazed breeding sites, and over-hunting. This decline has seen it listed in the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA).

The Ruff has a distinctive gravy boat appearance, with a small head, medium-length bill, longish neck and pot-bellied body. It has long legs that are variable in colour but usually yellow or orange. In flight, it has a deeper, slower wing stroke than other waders of a similar size, and displays a thin, indistinct white bar on the wing, and white ovals on the sides of the tail . This species shows sexual dimorphism. Although a small percentage of males resemble females, the typical male is much larger than the female and has an elaborate breeding plumage. He is 29-32 cm (11.4-12.6 in) long with a 54-60 cm (21.25-23.6 in) wingspan, and weighs about 180 g (6.4 oz). In the May-to-June breeding season, the typical male's legs, bill and warty bare facial skin are orange, and he has distinctive head tufts and a neck ruff. These ornaments vary on individual birds, being black, chestnut or white, with the colouring solid, barred or irregular. The grey-brown back has a scale-like pattern, often with black or chestnut feathers, and the underparts are white with extensive black on the breast. The extreme variability of the main breeding plumage is thought to have developed to aid individual recognition in a species that has communal breeding displays, but is usually mute.

Outside the breeding season, the typical male's head and neck decorations and the bare facial skin are lost and the legs and bill become duller. The upperparts are grey-brown, and the underparts are white with grey mottling on the breast and flanks.

The female, or "reeve", is 22-26 cm (8.7-10.2 in) long with a 46-49 cm (18.1-19.32 in) wingspan, and weighs about 110 g (3.9 oz). In breeding plumage, she has grey-brown upperparts with white-fringed, dark-centred feathers. The breast and flanks are variably blotched with black. In winter, her plumage is similar to that of the male, but the sexes are distinguishable on size. The plumage of the juvenile Ruff resembles the non-breeding adult, but has upperparts with a neat, scale-like pattern with dark feather centres, and a strong buff tinge to the underparts.

Typical adult male Ruffs start to moult into the main display plumage before their return to the breeding areas, and the proportion of birds with head and neck decorations gradually increases through the spring. Second-year birds lag behind full adults in developing breeding plumage. They have a lower body mass and a slower weight increase than full adults, and perhaps the demands made on their energy reserves during the migration flight are the main reason of the delayed moult.

Ruffs of both sexes have an additional moult stage between the winter and final summer plumages, a phenomenon also seen in the Bar-tailed Godwit. Before developing the full display finery with coloured ruff and tufts, the males replace part of their winter plumage with striped feathers. Females also develop a mix of winter and striped feathers before reaching their summer appearance. The final male breeding plumage results from the replacement of both winter and striped feathers, but the female retains the striped feathers and replaces only the winter feathers to reach her summer plumage. The striped prenuptial plumages may represent the original breeding appearance of this species, the male's showy nuptial feathers evolving later under strong sexual selection pressures.

Adult males and most adult females start their pre-winter moult before returning south, but complete most feather replacement on the wintering grounds. In Kenya, males moult 3-4 weeks ahead of the females, finishing before December, whereas females typically complete feather replacement during December and early January. Juveniles moult from their first summer body plumage into winter plumage during late September to November, and later undergo a pre-breeding moult similar in timing and duration to that of the adults, and often producing as brightly coloured an appearance.

Two other waders can be confused with the Ruff. The juvenile Sharp-tailed Sandpiper is a little smaller than a juvenile female Ruff and has a similar rich orange-buff breast, but the Ruff is slimmer with a longer neck and legs, a rounder head, and a much plainer face. The Buff-breasted Sandpiper also resembles a small juvenile Ruff, but even the female Ruff is noticeably larger than the sandpiper, with a longer bill, more rotund body and scaly-patterned upperparts.