NO. 4 AVIAN GENUS CLAMATOR — FRIEDMANN 69 



Study of their relatively poorly adjusted host relations in the African 

 part of their range. 



The situation present in the sub-Saharan Clamator glandarius as 

 compared with that in the circum-Mediterranean segment of the 

 species is reminiscent of Thorpe's (1930) biological races in insects. 

 He called attention (p. 189) to instances among species of insects and 

 allied groups in which geographically isolated populations with little 

 or no structural or pigmentary differences were definitely differ- 

 entiated biologically or behaviorally. These he considered essentially 

 the same as subspecies, but in which the racial characters are aspects of 

 the living rather than of the preservable parts of the specimens. As 

 I have already indicated I do not think it advisable to give separate 

 taxonomic or nomenclatorial rank to the two sections of Clamator 

 glandarius, as the size and color characters ascribed to choragium are 

 too slight and the overlap too great to make it a "usable" subspecies, 

 although choragium does reveal a trend toward differentiation, as yet 

 not well developed, and there is in its life history a biological difference 

 in its host relations and in its range of host selections. The very fact 

 that its behavioral character results in relatively poor coordination 

 in its host relations, coupled with the independent fact that its struc- 

 tural modifications are still only faintly developed, suggests that 

 "choragium" is a new, possibly as yet only an incipient, race. 



One further item in the plumage cycle of C. glandarius deserves 

 mention. Its juvenal plumage is blackish on the top of the head and 

 nape, not gray as in the adult. Because of this, Jourdain (1925, p. 

 661) suggested that this might have been produced through adaptive 

 evolution to achieve some degree of resemblance to the plumage of 

 the nestlings of its Palaearctic corvine hosts. Jourdain stressed that 

 the only conspicuous parts of the young bird while in the nest are 

 the crown and nape, and he accordingly discounted the pale tawny 

 chin and throat coloration. However, it may be recalled that the 

 critical moments for the nestling are when the foster-parent comes 

 with food. At such times the young cuckoo, as well as host young, 

 raise their heads and open their mouths widely and clamor for food, 

 and at such moments the throat would be no less visible than the 

 crown and nape. I cannot help but consider Jourdain's suggestion 

 as an "armchair speculation," and it certainly does not apply to the 

 stumid hosts the parasite uses in Africa. On the other hand, Cott 

 (1940, p. 422) was convinced enough to write that the nestling of 

 this cuckoo has a plumage ". . . whose crown has been influenced by 

 natural selection, but whose throat has been neglected — so that while 



