AVIAN GENUS CHRYSOCOCCYX 27 



Meliphagids) are all such as would make the islands suitable for the 

 glossy cuckoos. It is not easy to account for their disappearance as 

 breeders in the Solomons, as would be necessary if we were to assume 

 that they once were there. 



On the other hand, Fell (1947, p. 513) took the opposite view and 

 considered that if the southern, breeding range of C. I. lucidus and C. I. 

 plagosus were considered to be the old home of the two subspecies, 

 then their present migration routes, corresponding as they do with 

 the southeast trade winds, might be looked upon as a consequence of 

 the direction of these strong air movements. He went on to suggest 

 that one might consider the ancestors of these birds (typical lucidus) 

 to have been sedentary New Zealand birds, just as two other races of 

 the species (layardi and harUrti) are sedentary to this day, "and that 

 the migratory habit arose as a consequence of recent glacial conditions 

 rendering New Zealand inhospitable in winter. A similar history 

 might have occurred in Tasmania . . . ." 



It still seems to me more probable that the southern races of lucidus 

 were tropical in origin and then spread southward to their present 

 breeding ranges from which they returned to lower latitudes each 

 year. To say, as Fell does, that New Zealand is inhospitable in the 

 mnter can only mean that it is inhospitable to a tropical or semi- 

 tropical bird. 



Before discussing the migratory habits of each of the glossy cuckoos 

 it is necessary to recall that in the case of parasitic birds such as these 

 the adults may leave the breeding area long before the young of the 

 year and that the latter have little or no contact with the former 

 until they meet in the "wintering" grounds. In other words, the birds 

 of the year cannot possibly have any guidance, either directly or 

 indirectly, from older individuals of their own kind. Thus, Dove 

 (1925, pp. 43-44) noted that in Tasmania the adults of C. lucidus 

 plagosus and of C. basalis leave for the north about the end of Febru- 

 ary, but that the young of the year remain well into April. In discuss- 

 ing the New Zealand nominate race of C. lucidus, Mayr (1932) was 

 moved to vTite that "the migration of this species is very amazing, 

 and requires a perfect functioning of the entu'e 'instinct' appara- 

 tus. . . . On the average the young birds depart . . . later than the 

 adults. Nobody shows them the migration route, as their foster 

 parents (Gerygone and Ehipidura) are sedentary. ..." 



One other aspect of migratoriness should be mentioned before we 

 review the pictiu-e in each species of Chrysococcyx. We shall see that 

 in a number of these species part of the population is migratory and 

 part is not. In the case of three African species, klaas, cupreus, and 

 caprius, that breed in South Africa as well as in the equatorial portions 

 of the continent, the southern populations are definitely migratory 

 while their more northern relatives are not. Inasmuch as there is no 



