The indigobirds and whydahs, are a family, Viduidae, of small passerine birds native to Africa.
These are finch-like species which usually have black or indigo predominating in their plumage. The birds named "whydahs" have long or very long tails in the breeding male.
All are brood parasites, which lay their eggs in the nests of estrildid finch species; most indigobirds use fire-finches as hosts, whereas the paradise whydahs chose pytilias.
Unlike the cuckoo, the indigobirds and whydahs do not destroy the host's eggs. Typically, they lay 2–4 eggs in with those already present. The eggs of both the host and the victim are white, although the indigobird's are slightly larger.
Many of the indigo-plumaged species named "indigobirds" are very similar in appearance, with the males difficult to separate in the field, and the young and females near impossible. The best guide is often the estrildid finch with which they are associating, since each indigobird parasitises a different host speci