AVIAN GENUS CHRYSOCOCCYX 105 



More of a sequential, phylogenetic display of change can be found 

 through the genus in the matter of the ventral pattern of the first 

 pennaceous plumage. The young of the first of the three groups of 

 species mentioned above — malayanus, lucidus, basalis, and osculans — 

 are uniformly unbarred grayish-white below from the chin to the under 

 tail feathers; those of the other two groups have the underparts 

 heavily barred in their young, except for meyerii, which agrees in this 

 lespect A\dth the Australasian species, and, in so doing, acts as a perfect 

 "step" or intermediate between the Australasian group and the 

 Asiatic maculatus and xanthorhynchus. In its adult plumage meyerii 

 is already in line with the south Asian species; in its juvenal stage it 

 resembles malayanus, lucidus, basalis, and osculans. 



The variety of expression of migratory behavior is likewise a matter 

 of development within the several species rather than a traceable 

 progression throughout the genus. The great range of migratoriness, 

 from none at all to annual long-distance movements of as much as 

 2000 miles over open seas without landmarks, previous experience, or 

 even communication and guidance between successive generations, 

 is amazing in scope. However, it reveals no continuous pattern across 

 the genus. For that matter, it shows no uniformity even within the 

 same species. Thus, C. lucidus has four races, two of which are highly 

 migratory and two are sedentary. 



The main point of interest in this study has to do with the features 

 of brood parasitism exhibited by the members of the genus Chryso- 

 coccyx and particularly with clues to the course of evolutionary 

 changes in these features that a comparative survey might reveal. 

 The genus could hardly be expected to reveal any evidence as to the 

 origm and basic stages in the development of the parasitic mode of 

 reproduction, since it obviously evolved from a primordial cuculine 

 stock that was already entirely parasitic in its mode of reproduction 

 and that already had developed the evicting behavior in the very 

 young nestling and the egg-removing behavior in the adult. The glossy 

 cuckoos retained, to a greater degree than Cumulus (except for one 

 species, C. pallidus) and than most of the species of Cacomantis, the 

 atavistic habit of feeding fledged young of their own kind and, not 

 unrelated, the sunilar habit of courtship feeding of the adult hens by 

 the cocks. 



The present study shows that the glossy cuckoos have, m the course 

 of their history, greatly enlarged their range of hosts, but that, while 

 domg so, uidividual species of Chrysococcyx have come to concentrate 

 on partly or largely different groups within that broader range of 

 hosts. Thus, C. malayanus is restricted to a great extent to warblers 

 of the genus Gerygone, although one of its races, C. m. russatus, has 

 expanded its fosterer selection to include other hosts as well. C. lucidus 



