Imprinting and the origin of parasite-host species associations in brood-parasitic indigobirds, Vidua chalybeata

Brood-parasitic village indigobirds, Vidua chalybeata, were bred in captivi ty and foster-reared by their normal host species, the red-billed firefinch , Lagonosticta senegala, or by an experimental foster species, the Bengales e finch, Lonchura striata. Captive-reared female indigobirds were. tested a s adults for mate choice and for host choice. In tests of mate choice, fema le indigobirds responded preferentially towards mimicry songs of male indig obirds that were similar to those of the females' own foster parents. Femal es reared by Bengalese finches responded to male songs that mimicked Bengal ese finch song rather than to male songs that mimicked their normal host sp ecies, the firefinch. In tests of host choice, females reared by Bengalese finches laid in the nests of Bengalese finches, and females reared by firef inches laid in the nests of firefinches. Wild-caught females showed the sam e behaviours as captive-bred females reared by firefinches. A female indigo bird's social companions (firefinch or Bengalese) following her independenc e of her foster parents had no effect on her sexual response to male mimicr y song or her choice of a host species in brood parasitism. The results sup port the predictions of a model of imprinting-like behaviour development in which young indigobirds;focus their attention on their foster parents, rat her than a model of innate bias for songs and nests of their normal host sp ecies, or a null model of nonspecific brood parasitism and differential sur vival. The results provide experimental support for the recent origin of br ood parasite-host associations and the significance of imprinting in specia tion in these brood parasites. (C) 2000 The Association for the Study of An imal Behaviour.