page_title: Ruff (bird)
section_title: Nesting and survival
hierarchical_section_title: Ruff (bird) / Behaviour / Nesting and survival
context_page_description: The ruff 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.
  The ruff is a long-necked, pot-bellied bird. This species shows marked sexual dimorphism; the male is much larger than the female, 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.
context_section_description: The nest is a shallow ground scrape lined with grass leaves and stems, and concealed in marsh plants or tall grass up to 400 m (440 yd) from the lek. Nesting is solitary, although several females may lay in the general vicinity of a lek. The eggs are slightly glossy, green or olive, and marked with dark blotches; they are laid from mid-March to early June depending on latitude.
  The typical clutch is four eggs, each egg measuring 44 mm × 31 mm (1.7 in × 1.2 in) in size and weighing 21.0 g (0.74 oz) of which 5% is shell. Incubation is by the female alone, and the time to hatching is 20–23 days, with a further 25–28 days to fledging. The precocial chicks have buff and chestnut down, streaked and barred with black, and frosted with white; they feed themselves on a variety of small invertebrates, but are brooded by the female. One brood is raised each year.
  Ruffs often show a pronounced inequality in the numbers of each sex. A study of juveniles in Finland found that only 34% were males and 1% were faeders. It appears that females produce a larger proportion of males at the egg stage when they are in poor physical condition. When females are in better condition, any bias in the sex ratio is smaller or absent.
  Predators of waders breeding in wet grasslands include birds such as large gulls, common raven, carrion and hooded crows, and great and Arctic skuas; foxes occasionally take waders, and the impact of feral cats and stoats is unknown. Overgrazing can increase predation by making nests easier to find. In captivity, the main causes of chick mortality were stress-related sudden death and twisted neck syndrome. Adults seem to show little evidence of external parasites, but may have significant levels of disease on their tropical wintering grounds, including avian malaria in their inland freshwater habitats, and so they might be expected to invest strongly in their immune systems; however, a 2006 study that analysed the blood of migrating ruffs intercepted in Friesland showed that this bird actually has unexplained low levels of immune responses on at least one measure of resistance. The ruff can breed from its second year, and the average lifespan for birds that have passed the chick stage is about 4.4 years, although a Finnish bird lived to a record 13 years and 11 months.
caption: The carrion crow will raid the nests of wetland waders for eggs and young.
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