PARASITIC WEAVERBIRDS 65 



would be exceedingly difficult to make in the field, and even then 

 only under very favorable conditions. Still more important, cap- 

 tivity affords a good opportunity to view behavioral patterns, or 

 fragments of such patterns, away from the environment to which they 

 are adapted and in which they are apt to seem more purposive than 

 they really are. 



In the older literature are descriptions of nests attributed to com- 

 bassous, but practically all students of African birds consider these 

 descriptions in error. There is general agreement that combassous 

 are brood parasites entirely. I too agree, but feel that in all fau-ness, 

 the following cases, all based on birds in aviaries, should be presented 

 and discussed here. 



According to A. G. Butler (1899, p. 265) Russ, after years of effort 

 to breed combassous in captivity, noticed that — 



a female was continually flying round the nest of a pair of little Red Astrilds 

 [Lagonosticta sp.] and now and again slipped into it. The Ornamental Finches 

 did not permit themselves to be at all disturbed thereby. . . . But the female 

 of the latter never proceeded to egg-laying. . . . After a long time the female 

 Steel Finch dragged coarse bents into an already used, and very dirty Zebra 

 Finch nest, upon the compressed structure, and formed upon the latter a semi- 

 domed nest cavity. The laying of five eggs was incubated by the female alone 

 in twelve days, whilst the male defended the nest jealously, and pursued all 

 other birds, even very large ones, with outcry and flapping of wings. 



While this account states that the hen combassou buUt a nest 

 and incubated her eggs, there is no real evidence to prove this most 

 important pomt. There is too much likelihood of insufficient ob- 

 servation to rule out completely the possibility of the hen zebra 

 finch having been further involved. Unfortunately Russ's original 

 account (1884, pp. 175-176) gave no further data. True, Hopkinson 

 (1926, p. 27) appeared to accept Russ's claim to have bred combassous 

 (here identified (?) as Vidua chalybeaia), but Hopkinson added that 

 the first aviculturist to do so in Germany was Tittel. K. Neunzig 

 (1921, p. 33) meanwhile had stated that the bird had been bred 

 only once in German aviaries. 



A recent case in a Danish aviary reopens for appraisal the question 

 of possible nonparasitic breeding in the combassous. K. Nielsen 

 (1956, pp. 11-13) wrote that in 1951, A. Nielsen succeeded in breeding 

 combassous (Vidua chalybeaia) as parasites on a pair of fire finches, 

 which hatched and fed the young parasites. Furthermore, in 1955 

 K. Nielsen had — 



succeeded in breeding the Combasou, but in this case the Combasous them- 

 selves constructed the nest, hatched and fed the young. 



About the 1st of July I saw the male Combasou gather dry grasses, hemp, and 

 other kinds of nesting materials, but I didn't pay much attention to this, as I 

 had read . . . that the Combasous were parasites. ... It was only when I 



