AVIAN GENUS CHRYSOCOCCYX 81 



these very distinct egg types (in the relative frequency of their ac- 

 ceptance or rejection by the hosts), it is not possible to evaluate this, 

 the most striking distinction achieved by these two closely related 

 species. The degree to which both species use hosts that construct 

 domed or covered nests, with the consequent low level of illumination 

 surrounding the eggs, is one factor that obscures the evolutionary 

 value of the two diverse egg patterns. In the case of open nests this 

 factor would not be present, and since many eggs of both species are 

 deposited in such nests, the problem is open to further study. It is 

 hoped that it may be investigated by AustraUan ornithologists, and 

 the results should be of much interest. 



Mode of Egg -laying by Adult Cuckoos 



Mode of deposition 



While egg deposition is undoubtedly accomplished by direct laying 

 into the host nests in the great majority of mstances, no one has ever 

 reported an eye-witness account of it. This is not evidence against it; 

 it is merely the usual absence of direct observation that appUes even 

 to our knowledge of nonparasitic birds that are much easier to watch. 

 At the same time, some writers have concluded that, when parasi- 

 tizing certain types of nests, especially the small, semipendant ones 

 of some of the sunbirds, the glossy cuckoos may have to place the eggs 

 in them with their bills after having first laid them on the ground 

 nearby. Baker (1942, esp. pp. 122-132) reviewed all the data known 

 to him concerning European and Indian cuckoos and concluded that 

 he could find no "evidence to prove or disprove the contention that 

 one of the methods adopted by Cuckoos to place her egg in the nests 

 is by carrying it in her beak to the place she has chosen for it. I think 

 it is fuUy proved that she would not use this method if she could lay 

 in the nest direct or could project it into it through the entrance, 

 while supporting herself on the nest, or a twig, or something else. It 

 does happen, however, that Cuckoos' eggs are found in a great num- 

 ber of nests in which it would seem impossible to have placed them by 

 any other means than by the beak. 



"Personally, I think it is highly probable that this method is very 

 frequently adopted. ..." 



This kind of assumption has been made in the literature for some 

 of the glossy cuckoos in Africa, Australia, and Asia, but in almost 

 all instances it is unsupported by actual observations. However, in 

 the case of two of the Australian species, C. malayanus russatus and 

 C. basalis, there are on record some pertinent observations for each. 

 Because of the great interest attached to them they may be repeated 

 here. 



