All are brood parasites , which lay their eggs in the nests of estrildid finches .
The indigobirds are finch - like species which usually have black or indigo predominating in their plumage .
All are brood parasites , which lay their eggs in the nests of estrildid finches .
The indigobirds are finch - like species which usually have black or indigo predominating in their plumage .