404 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loe 



Inasmuch as this matter of removing an egg often involves the eating 

 of it by the didric, it may be noted that Caldcr (1951, p. 36) watched 

 a hen didric enter a nest of a thick-billed weaver {Amblyospiza 

 albifrons), emerge with an egg in its bill, and then eat the contents. 

 No cuckoo's egg was in the nest when it was examined a iew minutes 

 later, but it would seem that this weaver may have been intended as 

 a fosterer. It would not be surprising if someone were to find it to 

 act in this capacity. 



In the disputed matter of adaptive similarity between the eggs of 

 the cuckoo and those of its victims, the recently amassed data are just 

 as conflicting as was the older information. Reed noted a definite 

 simila^rity between didric eggs in nests of the red bishop bh'd and 

 those of the host, while Skead found noticeable contrast between didric 

 eggs and those of the builders in nests of Cape wagtails and Cape 

 weavers. 



Evicting Habit 



The evicting habit in this cuckoo still presents unsolved problems, 

 but the following data, subsequent to my earlier account (Friedmann, 

 1949a, pp. 179-181), are of interest. No one has yet seen a didric 

 chick in the act of ousting either eggs or young from the nest. The 

 evidence from which eviction is assumed to have taken place is merely 

 the fact that eventually the parasite is usually the sole occupant of 

 the nest. Assuming that the young cuckoo is responsible for the 

 disappearance of the other nest contents, Skead (1952, pp. 7, 9) found 

 that a nestling didric in a Cape wagtail's nest "tolerated" the two 

 eggs of the host for two days after it hatched, when one egg was found 

 below the nest and the other was out of the nest early the next 

 morning (i. e., after 2}^ days). In a Cape weaver's nest there were 

 two weaver's eggs when the didric hatched; the next day one of the 

 weaver's eggs hatched, but the following day both it and the unhatched 

 egg were gone, leaving the didric as sole occupant. In a spectacled 

 weaver's nest there was one egg of the host when a didric hatched; 

 both remained in the nest for two daj^s, after which the cuckoo was the 

 only occupant. From these three examples it appears that 2 or 2)^ 

 days may be the usual time for the "eviction" (or disappearance from 

 the nest) of the cuckoo's nest-mates. However, this is by no means 

 universal, as Reed (cit. supra) found in the case of a parasitized nest 

 of the red bishop bird. When the didric hatched there were two of 

 the host's eggs and one of its chicks in the nest, while four days later 

 the nest contained three chicks of the bishop bird and the young 

 cuckoo. Unfortunately, Reed's observations ended at that point. 

 However, in another nest of the same host species he found a didric 

 about four days old as the sole occupant. At 1 :30 p. m. he placed 

 two eggs of the bishop bird in the nest; by 6 p. m. (4^^ hours later) 



