14 U.S. NATIONAL MUSEUM BULLETIN 2 23 



birds before it may be possible to attempt to determine the precise causes and the 

 subsequent evolutionary paths that twice in the history of the weaverbirds have 

 led from nesting and incubation and caring for the young to a state of brood 

 parasitism. 



Since the loss of "normal," ancestral reproductive patterns and their 

 replacement by brood parasitism may involve antecedent weakenings 

 and trends in some of the components of the original picture — terri- 

 toriahsm, mating relations, nest building, incubation, and caring for 

 the young — these components will now be reviewed as far as available 

 data permit. 



Territorial and mating relations: We find much variability 

 within the weaverbird family in their territorial and mating relations. 

 Noting these variations gives us a clearer picture of the ethological 

 background of parasitic species and also helps us narrow the search 

 for factors contributive to brood parasitism, especially as our knowl- 

 edge of this portion of the life history of the several parasitic species 

 becomes more definite. 



As will be seen in the species accounts described below (beginning 

 on p. 39), some observers described individual species of viduines as 

 polygamous, wliile others described them as monogamous, but the 

 total evidence is not yet completely convincing about either interpre- 

 tation. 



Both monogamy and polygamy were noted in other sections of the 

 weaverbird family. In his recent study of buffalo weavers, Buhalornis 

 a. albirostris,^ Crook (1958) found that they are polygamous and ter- 

 ritorial. The territory may consist of a group of connected nests 

 comprising a "lodge," or a portion of a large and complicated "lodge," 

 but usually contains from thi-ee to six nest holes, with a hen installed 

 in each. Of the ploceine weavers, Moreau and Moreau (1939, pp. 

 317-318) reported that Ploceus aureoflavus,^ and jacksoni are poly- 

 gamous, while other species of the genus — bicolor,^ reichenowi, and 

 ocularius — ^are monogamous. Of hicolor and ocularius, Skead (1953, 

 p. 103) wrote that they appear to mate for life. The Moreaus con- 

 cluded that the distinction between monogamy and polygamy may 

 follow subgeneric lines. They found that — 



in the monogamous species mentioned above both members of the pair share the 

 building at all stages and share the care of the young, while in the polygamous 

 species all but the final stages of nest-building are done by the male, and the 

 female alone incubates and feeds the young. 



Jackson (1938) gives some indication of the function of the sexes for six of the 

 numerous Ploceus spp. mentioned by him. In Icteropsis pelzelni,^ both male and 



' CoccothrausUt alhirostTis VieiUot, Nouveau dictionnalre d'histoire naturelle, vol. 13, 1817, p. S35 (Sene- 

 gambla). 



• Ploceus aureoflavus A. Smith, Illustrations of the zoology of South Africa . . ., vol. 2, Aves, 1839, text to 

 pi. 30, fig. 1 (West Africa, probably Zanzibar). 



• Ploceut bicolor Vieillot, Nouveau dictionnalre d'histoire naturelle, vol. 34, 1819, p. 127 (South Africa). 



• SUagra pelzdni Hartlaub, Zool. Jahrb., vol. 2, 1887, p. 343, pi. 14, figs. 9, 10 (Maguogo, Upper Nile). 



