The Auk 112(3):649-658, 1995 SONG MIMICRY AND ASSOCIATION OF BROOD-PARASITIC INDIGOBIRDS (VIDUA) WITH DYBOWSKI'S TWINSPOT (EUSTICHOSPIZA DYBOWSKII) ROBERT B. PAYNE TMAND LAURA L. PAYNE • •Museumof Zoologyand 2Departmentof Biology,University of Michigan, Ann Arbor,Michigan 48109, USA AI•STRACT.--Apopulation of brood-parasiticCameroon Indigobirds (Viduacamerunensis) in Sierra Leone mimics the songsof its apparent foster species,Dybowski's Twinspot (Eusti- chospizadybowskii). Song mimicry includesthe widespreadsong elementsand phrasesand the major featuresof organizationof song(introductory units, terminal units, repetitionof certain units, and complexity in number of kinds of units in a song) of the twinspots.The songmimicry by indigobirdsof Dybowski'sTwinspots was predictedfrom a hypothesisof the origin of brood-parasiticassociations by colonizationof new foster speciesthat have parentalbehavior and habitatsimilar to their old fosterspecies. Indigobirds (Vidua spp.) now are known to mimic five speciesand generaof estrildidsthat are not firefinches(Lagonosticta spp.), their more commonfoster group. The evolutionarysignificance of songmimicry by indigobird populationsand speciesof severalgenera of estrildid finches,including the twinspot, is that the brood-parasiticindigobirds (Viduaspp.) appear to have associatedwith their fosterspecies through recentcolonizations rather than through ancientcospeciations. Received21 January1994, accepted 2 July 1994. THE AFRICANINDIGOBIRDS (Vidua spp.) are the Viduacospeciated with them and diverged brood-parasiticfinches that often are associated at the same time in parallel with their foster with the estrildid firefinches(Lagonosticta spp.; species (Nicolai 1964, 1969, 1973). However, Nicolai 1964, 1967, 1968, Payne 1968, 1973a, other explanationsare possible.In contrastto a 1982).The adult male mimicsthe songsof the hypothesis of cospeciation,we have proposed foster species,which he learns from the foster a hypothesis of associationby colonization, species.He directs the song to the female in- when a brood parasiteswitches from one foster digobird, and not to the foster speciesitself species to another (Payne 1973a, Klein et al. (Payne 1973a, 1985). The young indigobird 1993, Payne et al. 1993). There is evidence for mimics the mouth pattern of the nestlingsof an occasionalsuccessful shift of foster species. the foster species.The breeding female visits In areaswhere two or morekinds of indigobirds the singingmale indigobird at his call-site,the live together,each usually with a different fos- place where he perchesand singson exposed ter species,a few males mimic the songsof the branches in the top of a tree, and she mates alternate foster species(Payne 1973a,Payne et with him there. In at least some areas where al. 1993). Although most kinds of indigobirds two or more kinds of indigobirdslive together, are associated with firefinches, recent fieldwork the birds behaveas distinct biologicalspecies; has revealed distinct populations of indigo- males and females differ in size and color from birds, some of them distinct species,that are other kinds of indigobirds, and each female associated with other kinds of estrildid finches. mateswith a male that mimics the songsof her In southern and easternAfrica, the indigobird own foster species(Payne 1973a, Payne and speciesVidua codringtoniis associatedin song Groschupf1984, Payne et al. 1993).This behav- mimicry, in distribution, and presumably in a ior may assurethat she mates with a male that, species-specificbrood-parasitic relationship with asshe did asa nestling,mimics the mouthcolors Peters'Twinspot (Hypargosniveoguttatus; Payne and patterns of the young of the same foster et al. 1992, 1993). In western Africa, V. nigeriae species,and that their offspring also will have is associatedwith the Quail-finch (Ortygospiza this pattern. atricollis), and V. raricola is associated with the The closeassociations of indigobirdswith the Goldbreast(Amandava subfiava). Also, some pop- fosterestrildid speciesled to a suggestionthat ulations of the Cameroon Indigobird (V. ca- 649 650 P^¾NE^ND P^¾NE [Auk, Vol. 112 merunensis)are associatedwith the Brown Twin- shehad laid andwas incubating. Small estrildid finches spot (Clytospizamonteiri), while others are as- of the grassand bushywoodlands of Africagenerally sociated with certain firefinches (Payne and nest late in the rains and early in the dry season Payne 1994). (Moreau 1966, Immelmann and Immelmann 1967, Our fieldwork was designedto test a predic- Payne 1973a,Elgood 1994, Payne and Payne 1994). The nest found at Freetown, Sierra Leone, had five tion of the colonization hypothesis:if the as- eggs in October (G. D. Field in litt.), and the obser- sociationsof indigobirds and their foster spe- vation of a family group in Nigeria on 4 February cies are the result of colonizations of new foster (Wilkinsonet al. 1987)indicates a nestingin Decem- speciesrather than of ancientcospeciations, then ber. we expect to find additional associationsof in- CareerDonIndigobird song mimics of Dybowski's digobirds with other speciesof estrildids that Twinspotswere observedand tape recordedfrom 23 are similar in parental behavior and habitat to to 28 September 1993 within 4 km of Kabala. The the known foster species. The associationsof indigobirdswere singing from the exposedtwigs on indigobirds with two speciesof twinspots in topsof bushesand treeslocated in gardensin town, southern, eastern, and west-central Africa led as well as those locatedin cultivated fields along the roadswest towards Yagala and east towards Koina- us to searchfor songmimicry of a third species, dugu. As in other kindsof indigobirds(Payne 1973a, Dybowski's Twinspot (Eustichospizadybowskii), 1979, 1985, Payne and Payne 1994), each of the six in western Africa in Sierra Leone. males that we recorded had a set of chatters and com- plex songs(the nonmimeticsongs of the indigobird) FIELD OBSERVATIONS AND METHODS that did not resemble a foster estrildid, as well as a Dybowski'sTwinspot occurs in open grassywood- set of songs (the mimetic songs) that matched the land and grassyrock outcropsin extreme western songsof the twinspots.The malescourted the females Africa in Senegal,Guinea, Sierra Leone, northern Li- that visited them at their call-sites.Display and be- beria and extremewestern Ivory Coast,and in west- havior were similar to the Village Indigobird (V. chal- central Africa from Nigeria, CareerDon,Central Af- ybeata),which has been observedin detail (Payne rican Republic,Sudan, the Uelle region of Zaire, and 1973a, 1985). The indigobirds sang in the morning Uganda (Hall and Moreau 1970, Mackworth-Praed but not all day, and they fed in groups,suggesting and Grant 1973, Dowsett and Dowsett-Lemaire 1993, that Septemberwas early in their breeding season.A Matthews1995). It feedson the ground,where it takes flock of about 30 indigobirds flew from a feeding area smallgrass seeds and insects.Only one nesthas been in finger millet to a mangogrove, where they roosted seenin the field in Africa (in SierraLeone; Field 1968), at dusk. One copulationwas seen. The female flew and juvenilesin a family group have been seenin to the singing male on his call-site.He hovered over Nigeria (Wilkinsonet al. 1987).It hasbeen bred by her, they matedfor 3 s, and then he flew to the ground aviculturists,and their descriptionsprovide most of andfed; she joined him. No juvenileindigobirds were what we know about its behavior. Like most estrildid seen. finches,Dybowski's Twinspot lays in well-concealed Three kinds of indigobirds are known at Kabala. covered,thatched grass nests, and both parentsre- GoldbreastIndigobirds (V. raricola)are bright glossy gurgitate seeds and occasionalinsects to their off- green; they mimic the songs of Goldbreasts.They spring,which begwith a characteristichead-twisting were tape recorded and captured at Kabala in 1973 behavior (Kunke11959, Immelmann et al. 1965, 1977a, (Payne 1976, 1982, Payne and Payne 1994);we saw Kujawa 1965,Pensold 1974, Goodwin 1982,Clewing one in 1993,but it did not sing. The other indigobirds 1988, Quoos 1990, Yantz 1991, Vit 1992). were blue, but were not captured.In September1993, Dybowski's Twinspots were observed at Kabala we recordedsix blue malesthat mimicked the songs (09ø35'N,1 Iø33'W), Koinadugu District, SierraLeone, of Dybowski'sTwinspots and six blue malesthat mim- in December 1973 and September 1993, and at icked the songsof African Firefinches (L. rubricata). Ngaoundere (07ø22'N, 13ø34'E), Tibati (06ø28'N, In December 1973, R.B.P. recorded two blue mimics 12ø38'E),and Banyo (06ø45'N,IIø50'E) in northern of this firefinch(Payne 1976). All of the singingmale CareerDonin January1979 and October1980 and 1992. blue indigobirds(both twinspot mimicsand firefinch At Kabala,the rainy seasonis from May throughOc- mimics)appeared to have the samecolor and intensity tober,with eachmonth averagingmore than I00 mm of glossin breedingplumage, and the samepale wings of rainfall (Gwynne-Joneset al. 1978).By December and pale purplish feet; it is on this basisthat we the grassis dry and the hillsidesare burned (Payne identifiedthem as V. camerunensis(cf.Payne and Payne 1976).In Septemberthe twinspotsfed on fallen grass 1994). Goldbreasts and African Fire finches were seen seeds,especially finger millet ("funde") in cultivated there with Dybowski'sTwinspots. The other estril- fieldswhere the smallseeds were being harvested.A dids at Kabalaknown as fosterspecies of certain in- female netted on 26 September1993 was in fresh