AVIAN GENUS CHRYSOCOCCYX 



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Figure 3. Probable evolutionary dispersals of Chrysococcyx: 1. dispersal, from 

 Malaysian area to Australia and New Zealand, facilitating the differentiation 

 of lucidus, basalis, ruficollis, and osculans; 2. secondary movement, to New 

 Guinea with the development of meyerii; 3. third dispersal, to southern Asia 

 with the development of maculatus and xanthorhynchus ; 4. fourth dispersal, to 

 Africa with the differentiation of flavigularis, klaas, cupreus, and caprius. 



Migratory behavior 



In an evolutionary study such as this, migratory behavior poses 

 two separate problems. The fii-st is the evolution of migration paths 

 and habits within the group; the second has to do with the effects of 

 seasonal movement on further evolution within the members of the 

 genus. A number of authors have emphasized the role migratoriness 

 plays in gene dispersal and have stated that it tends to reduce the 

 chances for subspeciation by mixing up tbe populations from several 

 breeding areas while in the common nonbreeding, "wintering" gi-ounds 

 each year. Mayr (1963, pp. 417-418) has mentioned the high incidence 

 of monotypic species in the migratory North American warblers, Pa- 

 rulidae, as a case in point. He has also noted that the equally migratory 

 buntings, Emberizidae, on the other hand, show great geographic — or 

 racial — variability, but suggested that this may be due to the fact 

 that they are ground-living birds, perhaps more critically exposed to 

 selective pressures by predators and by microclimates than are the 

 largely arboreal Parulids. The glossy cuckoos are largely arboreal, but 

 they do not present a clear correlation of monotypy with migratoriness 

 or, on the other hand, of pol3^typy with sedentariness. Thus, three 

 species {ruficollis, meyerii, and flavigularis) are monotypic and non- 

 migratory; four others (basalis, osculans, maculatus, and caprius) are 

 monotypic and migratory; the most higlily polytypic species (mal- 



267-562—68 3 



