Rb. Payne et al., SONG LEARNING IN BROOD-PARASITIC INDIGOBIRDS VIDUA-CHALYBEATA - SONG MIMICRY OF THE HOST SPECIES, Animal behaviour, 55, 1998, pp. 1537-1553
Brood-parasitic village indigobirds, Vidua chalybeata, were bred in ca
ptivity and foster-reared by their normal host, red-billed firefinch,
Lagonosticta senegala, or by an experimental foster species, Bengalese
finch, Lonchura striata. Male indigobirds reared by Bengalese finches
developed the songs of Bengalese finches, and males reared by firefin
ches developed songs of firefinches. Males copied their foster father
only when they had lived with him long after independence (45 days pos
t-fledging), while males separated normally at independence (22-24 day
s post-fledging) copied songs of other individuals and not songs of th
eir foster father. Males reared by Bengalese finches showed no prefere
nce to learn firefinch song over songs of the experimental foster spec
ies or other control finch species even when they had lived with firef
inches as companions from the time of fledging to independence. Males
copied several song themes, acquired the same number of mimicry songs,
and acquired their songs at the same age, whether reared by Bengalese
finches or by firefinches. When they lived with other indigobirds, th
e male indigobirds copied mimicry songs of male indigobirds that mimic
ked the same foster species. We predicted mimicry-song specificity and
repertoire size in experimental indigobirds from a hypothesis of an ea
rly developmental period when young indigobirds focus their attention
on their foster patents, and a later period when they direct their att
ention to other birds with similar songs. The predictions, based on fi
eld observations of wild birds, were that (I) males reared by a novel
foster species other than the normal host would learn the song of that
foster species, and (2) males that left their foster parents at the n
ormal time of independence would copy the songs of other individuals,
including other adult indigobirds that mimicked the same foster specie
s. Begging calls of young indigobirds did not mimic the calls of young
firefinches. Indigobirds reared alone, or with young of the normal ho
st or of the experimental foster species, all developed begging calls
in adult song that resembled their own begging as nestlings and fledgl
ings, and only males that heard other adult indigobirds with firefinch
-mimicry begging developed firefinch begging in their song. The incorp
oration of the innate begging calls as well as the learned begging cal
ls into adult song, and the modification of the song themes of their i
ndividual song models, suggest that song development involves processe
s in addition to copying the songs of their own foster species and of
older adult male indigobirds with songs like their own foster parents.
(C) 1998 The Association for the Study of Animal Behaviour.