AVIAN GENUS CPIRYSOCOCCYX 



29 



a race of the same species. Deigrian has suggested that it might be 

 necessary to consider rufomerus and crassirostris as a separate specific 

 group, but this seems unlikely, since the only diagnostic character they 

 have in common and in which they differ from the other forms of 

 malayanus is a deep, metallic, bluish-black subterminal area on the 

 central tail feathers. 



It would seem (and present knowledge does not permit a stronger 

 word) that minutillus may be partly migratory, that these wandering 

 individuals are not breeding birds in the areas to which they roam, or, 

 less likely, that minutillus may have achieved a status of genetic 

 distinction enabling it to "invade" the ranges of rufomerus and of 

 crassirostris without danger of phenotypic swamping. Actually, the 

 whole history of C. malayanus with its high degree of geographic mor- 

 phism suggests that it must have been a geographic "expander" or 

 migrant, but that its members remained as sedentary "founder" 

 groups in the various islands it had encompassed in its expansion. 



In C. lucidus we have another polytypic cuckoo, with four races, 

 two of which are highly migratory {lucidus and plagosus) and two 

 resident where found {harterti and layardi). Much is known of the 

 movements of the two migratory races, as may be seen from the 

 following summary, based largely on the data supplied by IMayr (1932) 

 and more recently and more fully by Fell (1947). The accompanying 

 map is from Van Tyne and Berger (1959, p. 185) based on Fell's report. 



APPROXIMATE 



SUMMER RANGE 



(plagosus) 



Figure 4. Migration of two races of Chrysococcyx lucidus (ex Van Tyne and Berger) 



