PARASITIC WEAVERBIRDS 103 



fact that a captive bird in an aviary laid its egg on the bare ground 

 (Bolus, 1909, p. 113). V. G. L. van Someren's observations (quoted 

 above) are evidence to the contrary. Roberts was probably influenced 

 by the then current ideas about the egg laying of the European cuckoo. 



Recently IMackworth-Praed and Grant (1955, pp. 1046-1047) 

 noted that the hen pintail may at times lay the first egg in the nest. 

 Although no basis for this statement was given, it is apparently 

 taken from J. Vincent (1936, p. 114), who wrote that the common 

 waxbill does not appear to resent the intrusion of the parasite "as in 

 some instances it has been almost certain that the whydah was the 

 first to lay." Unfortunately, the details that seemed to make 

 this "almost certain" were not recorded. 



A few observations have also been made about the incubation 

 period. Skead (1957) found a nest of the common waxbill containing 

 seven eggs of the owner and one of the pintail, on November 30. 

 On December 10 the pintail and four of the waxbills hatched. The 

 last of the waxbill's eggs hatched on December 13. From November 

 30 to December 10 is 11 days, so that the incubation period of the 

 pintail must have been something over that. In his acount of this 

 waxbill, V. G. L. van Someren (1956, p. 493) wrote that its incubation 

 "lasts about eleven days." 



Another estimate of the incubation period, based on a breeding 

 instance in the aviary of H. David and kindly sent me by G. A. 

 Radtke, is somewhat longer. The egg was found freshly laid in a 

 deserted nest of a pair of zebra finches (Taeneopygia castanotis), and 

 was then placed under a brooding bengalese finch (Lonchura striata), 

 whose own eggs proved to be infertile. The egg hatched "within a 

 fortnight or so," but no accurate time record was kept. 



The question of mimetic similarity between the eggs of the pintail 

 and those of its hosts seems to have been avoided because most of 

 the victims (the various species of waxbUls) lay unmarked white eggs 

 much like those of the pintail; however, the pintail is not completely 

 restricted to victims with similar egg types. The tawny-flanked 

 longtail lays eggs varying from bluish green to salmon pink and pale 

 brown pencilled or blotched with purplish gray or brown. The spot- 

 backed weaver lays brown-spotted blue, green, or whitish eggs. The 

 red-coUared whj'dah's eggs are bluish green, tinged with pale lavender 

 gray, and speckled with brown. The streaky seed eater lays bluish 

 or whitish eggs with fine brownish scrawls on them. 



Old accounts in the literature describing the nests and eggs of the 

 pintail (von Heuglin, Stark, Alexander, Teschemaker, 1910b, and 

 others) are erroneous and should be disregarded. A most confusing 

 statement was made years ago by Knauer (1889, p. 396), who ^^Tote 

 that in the Vienna Zoo the pintails diligently built nest after nest, and 



