62 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I46 



to migrating . . ." The most that may be said in the case of this 

 cuckoo is that fledgling feeding is yet to be proved. 



The mere act of courtship feeding, as shown in the jacobin 

 cuckoo, is in itself an atavistic behavior, and if it should eventually be 

 found to be coupled with even occasional feeding of fully fledged 

 young (other than by mistaking them for adult females) this 

 would further strengthen the suggestion that Clamator is a fairly 

 primitive genus of parasitic cuckoos. 



PLUMAGE VARIATIONS AND THEIR SIGNIFICANCE 



Before we discuss the polymorphisms which have been well es- 

 tablished in two of the four species of Clamator, jacobinus and levail- 

 lantii, it is necessary to review the extent and the nature of the 

 variations found in the "normal" plumages as well as in their 

 melanistic phases. 



Although not pertinent to the immediate problem of polymorphism, 

 the plumage variations of the climax species C. glandarius also may 

 be described and discussed in this section of the paper, as they have 

 pertinent evolutionary implications as well. C. coromandus calls for 

 no comment here. 



Clamator levaillantii 



The "normal," i.e., the white-breasted, plumage has the entire un- 

 derparts from chin to vent white, with black streaks on the chin, 

 throat, breast, and upper abdomen, these streaks narrowing to shaft 

 lines on the feathers of the sides, flanks, and undertail coverts, the 

 streaks heaviest on the throat and upper breast ; all the rectrices with 

 broad white tips crossing both webs, and with a white patch on the 

 outer eight primaries, this patch not visible from above in the closed 

 wing because of the overlapping secondaries ; under wing coverts white 

 with very variable amounts of black markings. The entire upper 

 surface of the head and body is solid black. 



Here we find variations in the mental and pectoral stripes from 

 specimens in which these dark marks are narrower than the white 

 interspaces (the lateral portions of the feathers are here involved) 

 to others in which the dark marks are broadened to the degree that 

 they become practically coalesced to form almost solid black areas on 

 the chin and upper throat. Although no geographic races of the 

 stripe-breasted cuckoo are recognizable, much attention has been paid 

 by authors to the degree of the variation, especially in the heaviness, 

 the length and width, and the darkness of the blackish stripes on 



