Physical characteristics

The weavers have no defining physical characteristics which are shared by all or even most members of the family. The sexes may be virtually indistinguishable, even in the hand, or highly dimorphic. Tails can be short or extravagantly long. The bill is always straight, not curved, but varies from short and heavy to longer and quite slender. At the sub-family level, there is more consistency. Buffalo weavers are either mainly black or mainly white, with heavy seed-eater bills. Sparrow-weavers are all "sparrowy" brown in appearance, with some black or white plumage areas. There is no obvious seasonal plumage change in either of these groups, and little sexual dimorphism, although males are usually larger. Within the parasitic Viduinae, there is marked sexual dimorphism in plumage during the breeding season, after which males molt into a plumage which resembles that of the females. They can usually be disinguished from other small seed-eating birds by black stripes on the crown of the head. Male indigobirds are blackish, with pale or reddish bill and legs, in varying combinations. Male whydahs have mainly black or black-and-white breeding plumage with very long central tail feathers, which may be either narrow or broadened. The male cuckoo finch is canary-yellow in breeding plumage.

Among the Ploceinae, there are conspicuous differences between genera. Males are almost always larger than females, while sexual dimorphism in plumage is especially marked in polygynous species. However, even in dimorphic species, the males do not always have a seasonal plumage change. Eye color often changes with age from brown to red, yellowish, or creamy; in many cases only males have a distinctively colored eye. The bill color of male birds may change seasonally from brown to black, in response to increased levels of male sex hormones. The genus Malimbus is remarkably uniform. All species are predominantly black with some red, or in one case yellow, plumage; males and females differ in plumage, and juvenile birds have a distinctive plumage, different to both adults. There is no seasonal change in plumage. In contrast the open-country bishops and widows (Euplectes) all have spar-rowy brown females, while males molt into a breeding plumage which is wholly or partly black, with either red or orange to yellow areas, and in some cases a long, black tail. Young birds resemble females, and males do not usually acquire breeding plumage until at least their second year. The large genus Ploceus includes species that are sexually dimorphic with or without a seasonal change in plumage, and species in which the sexes are identical. Black and/or yellow are the predominant plumage colors in males, with some green, brown, or orange, but never red, feathers.

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