46 U.S. NATIONAL MUSEUM BULLETIN 22 3 



Delacour (1943, p. 71) considered that cuckoo finches are in a less 

 advanced stage of parasitism than are the viduine weavers, as the 

 former victimize various small warblers, while the viduines are largely 

 restricted to estrildine species, with whose nestlings viduine nestlings 

 have in common distinctive mouth patterns and plumages. Any 

 attempt to read into the viduines a more highly speciahzed degree of 

 brood parasitism must be based on the assumption that these remark- 

 able mouth patterns are a highly adaptive feature, but, as was already 

 discussed, this buccal similarity is indicative more of a common an- 

 cestry and close relationship between the parasites and their main 

 hosts than of something acquired to expedite their success with their 

 hosts. 



On the consid eration that the ploceine weavers may have originated 

 from the Cisticolinae, and the further consideration that the cuckoo 

 finch is a ploceine species, Beecher (1953, p. 304) concluded that in 

 its parasitism of grass warblers, the cuckoo finch presents a parallel 

 to the screaming cowbird, which usually parasitizes its close relative, 

 the bay-winged cowbird. The two cases are, however, quite dissim- 

 ilar, as the two cowbird species are extremely closely related, the 

 baywing being practically the inmiediate ancestor of its parasite, 

 while no one would think that the cuckoo finch is close to the grass 

 warbler. 



All the known victims of the cuckoo finch and the available records 

 of each are given below. All cases refer to the nominate race of the 

 parasite. 



Wren grass warbler: Cisticola juncidis (Rafinesque) <* 



Two races of wren grass warblers are known to be parasitized — 

 C.j. perennia Lynes ^° and C.j. terrestris (Smith) .^^ Pakenham (1939, 

 p. 553) found perennia victimized frequently in Pemba. On one oc- 

 casion, he noted two nests, the first nest containing one and the other 

 nest two young cuckoo finches. On another occasion, he saw a pair 

 of wren grass warblers feeding two fledgling cuckoo finches ah-eady 

 out of the nest. He wrote that in Pemba the cuckoo finch parasitizes 

 this host very intensively from September to January. After the 

 period covered by his publication, Pakenham observed additional 

 cases of recently fledged cuckoo finches being fed and attended by 

 wren grass warblers at Konde, North Pemba Island — one in November 

 and two in February. 



The race C. j. terrestris was first found to be victimized near Um- 

 vuma. Southern Rhodesia, on February 14, 1939, when A. W. Vincent 



** Sylvia juncidis RaflnosQue-Schmaltz, Carratteri . . . anlmall . . . SiclUa . . ., 1810, p. 6 (Sicily). 



» Cisticola juncidis perennia Lynes, Ibis, ser. 12, vol. 6, 1930, Cisticola supplement, p. 105 (Motla, near 

 Lake George, I.e., Riiwenzori). 



UDrymoica terrestris A. Smith, Illustratinns of the zoology of South Africa . . ., vol. 2, Aves, 1842, pi. 74, 

 fig. 2 (between Latal^oo and Kurrichane, Bechuanaland). 



