PARASITIC WEAVERBIRDS 7 



supposedly most archaic section of the whole family complex. 

 This character and the skull never becoming thickly ossified on 

 top; the marked seasonal change of plumage (in the males); the 

 streaky, "sparrowy" plumage of the females, nonbreeding males, and 

 immature birds of both sexes; and the parasitic mode of reproduc- 

 tion justifies oiu" considering the combassous and their long-tailed 

 relatives as a subfamily, Viduinae, distinct from the Estrildinae. 



Still another character by which the Viduinae differ from the 

 Estrildinae is the peculiar type of scratching movement used by the 

 former in searching for food. Poulsen (1953, pp. 37-38) recently 

 described this for Vidua macroura, V. regia, V. chalybeata, and 

 Steganura paradisaea, which he studied in the zoological park at 

 Copenhagen. These birds — 



when seeking food on the ground, made small hopping movements on both legs. 

 When their spread feet touched the ground some of the earth was spread about 

 and the birds obtained some seeds lying in the loose soil, i.e., a kind of primitive 

 scratching movement. . .. Previously the weaver birds (Ploceidae) were divided 

 into two subfamilies: Ploceinae and Estrildinae. The whydah birds were classed 

 with the latter subfamily. There is, however, no doubt about these birds which 

 are parasites and in addition possess this "scratching movement" form a distinct 

 group. . . . Three genera . . . Drepanoplectes, Diatropura, and Coliuspasser 

 are very much like the whydah birds (Viduinae in , . . appearance. . . . They 

 are, however, not parasitic, and ... do not possess the above mentioned "scratch- 

 ing movement" as the Viduinae. 



The fact that the viduines are restricted to the open grasslands of 

 Africa is in general agreement with Sushkin's placement of them near 

 the base of the estrildine stem, rather than near the top as Chapin had 

 earlier suggested. The forms that dispersed to more remote areas 

 (remote, that is, from the African savannas) were the later evolution- 

 ary offshoots of the Estrildinae, not their more archaic relatives. 

 Beecher (1953), to the contrary, concluded that the "inability (of the 

 viduines) to reach Australia and their poorness in species suggest a 

 relatively late origin from the Ploceidae." Beecher considered the 

 viduines a section of the typical ploceine weavers, and not of the 

 estrildines, and it is only the latter group that occurs in Australia, 

 where Beecher assumed that they originated, and then spread to 

 Africa. Morris (1958), however, concluded that the estrildine group 

 originated in Africa and spread from there across Asia to Australia. 

 "This probably involved ancestral mannikin forms, which gave rise to 

 the grassfinches when they reached Australia. Many of the grass- 

 finches are now extremely convergent with certain African waxbills. 

 The alternative evolutionary scheme ... is that both ancestoral 

 mannikins and waxbills spread round to Australia and that the grass- 

 finch group is not a natural unit, but that part of it has come from 



