Ruff (bird)

Description

The ruff is a stocky wader with a pot-bellied shape, a small head, a medium-length bill, a longish neck, and a heavy body. Its long legs change color depending on age and season: dark greenish in juveniles, pink to orange in adults, and reddish orange in some males only during breeding. When flying, its wingbeats are deeper and slower than those of other waders its size, and it shows a faint white wing bar and white oval patches on the sides of its tail.

The species is strongly dimorphic. Most males are much larger than females, though a few males resemble females. The typical male measures 29 to 32 cm in length, has a wingspan of 54 to 60 cm, and weighs between 130 and 254 g, making it the largest bird in the genus Calidris. During the breeding season from May to June, the male’s legs, bill, and warty bare facial skin turn orange, and he grows distinctive head tufts and a neck ruff.

These ornaments vary widely among individuals, appearing black, chestnut, or white, with solid, barred, or irregular patterns. The grey-brown back has a scale-like look, often mixed with black or chestnut feathers, while the underparts are white with extensive black on the breast. This extreme variation in breeding plumage likely helps individuals recognize each other during communal displays, though the bird is usually silent. Outside breeding, the male loses his head and neck decorations and the bare facial skin, and his legs and bill become duller.

His upperparts turn grey-brown, and his underparts become white with grey mottling on the breast and flanks. Females, called reeves, are 22 to 26 cm long with a wingspan of 46 to 49 cm and weigh 70 to 170 g.

In breeding plumage, they have grey-brown upperparts with white-edged, dark-centered feathers, and their breast and flanks are variably blotched with black. In winter, females resemble males in plumage but can be told apart by size. Juveniles look like non-breeding adults but have a neat, scale-like pattern on the upperparts with dark feather centers and a strong buff tint on the underparts.

Distribution and habitat

The ruff is a migratory bird that breeds in the cold wetlands of northern Eurasia and winters in tropical regions, mostly Africa. Some individuals from Siberia travel up to 30,000 kilometers each year to reach West Africa. In western Europe, its breeding and wintering ranges barely overlap. This species nests in large lowland freshwater marshes and damp grasslands, steering clear of barren tundra and areas hit hard by severe weather.

It favors hummocky marshes and deltas with shallow water. The wetter parts supply food, while mounds and slopes serve as display grounds for leks, and dry spots with sedge or low scrub provide nesting sites. A study in Hungary found that moderately grazed grasslands with more than one cow per hectare attracted more nesting pairs. Outside the breeding season, the ruff uses a broader variety of shallow wetlands, including irrigated fields, lake edges, mining subsidence areas, and other floodlands.

Dry grassland, tidal mudflats, and seashores are used less often. Population density can reach 129 birds per square kilometer but is typically much lower.

The ruff breeds from Scandinavia and Great Britain eastward nearly to the Pacific. In Europe, it lives in cool temperate zones, but across its Russian range it is an Arctic species, mostly found north of about 65°N. The largest breeding populations are in Russia (over one million pairs), Sweden (61,000 pairs), Finland (39,000 pairs), and Norway (14,000 pairs). Fewer than 2,000 pairs breed in Britain, the Low Countries, Poland, Germany, and Denmark.

Behaviour

During breeding season, male ruffs gather at a traditional open grassy area called a lek to perform displays. Unusually for a lekking bird, these displays are aimed more at other males than at females. The species is also one of the few where males have clear, inherited differences in both feather color and mating style. Three male types exist: territorial males, which make up about 84 percent and have bold black or chestnut ruffs; satellite males, about 16 percent, with white or mottled ruffs; and a very rare form that looks like a female.

Each male keeps the same appearance and behavior for life, determined by his genes. Territorial males claim small mating spots on the lek, roughly a meter wide, often with bare soil at the center. Five to twenty such males hold these spots, actively courting females and showing strong aggression toward other territory holders. Their display includes wing fluttering, jumping, standing tall, crouching with ruff raised, or lunging at rivals.

They are usually silent while displaying, though a soft gue-gue-gue may occur. These males are very loyal to their sites; 90 percent return to the same lek in later seasons, with the most dominant ones most likely to come back. This faithfulness helps them learn rivals’ strengths, reducing fights and injuries, and keeping aggression low so females are not scared off. Lower-ranked males also benefit by staying on the lek until top males retire.

Satellite males do not hold territories but visit leks to mate with females on resident males’ spots. Residents tolerate them because having both types attracts more females. Females also favor larger leks and those surrounded by taller plants, which offer better nesting.

Conservation status

The ruff is a widespread bird, with a total range covering between one and ten million square kilometers and a global population of at least two million individuals. In Europe, which holds more than half of the breeding range, there are an estimated 200,000 to 510,000 breeding pairs.

Over a ten-year period, this European population appears to have dropped by as much as 30 percent, though this could partly reflect shifts in where the birds choose to breed rather than an overall loss. On a global scale, the ruff was last evaluated in 2016 and classified as a species of least concern. However, in 2021, the IUCN assessed the European population as near-threatened, a status that might eventually lead to an uplisting of the entire species.

The most significant breeding populations, found in Russia and Sweden, remain stable, and the breeding range in Norway has expanded southward. In contrast, numbers have fallen by more than half in Finland, Estonia, Poland, Latvia, and the Netherlands. Although these countries hold only small populations, the decline continues a pattern of range contraction that has been underway for the past two centuries. This drop is linked to drainage, increased use of fertilizers, the loss of traditionally mown or grazed breeding sites, and over-hunting.

Pleistocene fossils indicate that the ruff once bred farther south in Europe during the cool periods between glaciations. Its sensitivity to climate, water table levels, and the speed of vegetation growth suggests that global warming may be affecting its range, making it a potential indicator species for monitoring climate change.

Additional threats include outbreaks of diseases such as influenza, botulism, and avian malaria. Under the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA), the ruff is placed in category 2c, meaning its populations require special attention due to a significant long-term decline across much of its range. This obligates signatory countries to regulate hunting, protect habitats, and monitor the birds.

Did You Know?

• The ruff was first described by Carl Linnaeus in 1758 as Tringa pugnax.
• Ruffs were formerly trapped for food in England; 2,400 were served at Archbishop Neville's enthronement banquet in 1465.
• The specific epithet pugnax comes from the Latin term for 'combative', referring to the bird's aggressive behaviour at mating arenas.