124 THE BIRDS OF BRITISH GUIANA. 



coloring. Cases of such birds, shown in the British Guiana 

 exhibit in the Columbian Exposition, have been a revelation 

 and a marvel to visitors who, at the same time that they 

 can hardly believe such brilliant tints to be natural, yet 

 realize that they could not be produced by artificial means. 

 In many cases this brilliance is only characteristic of the 

 adult males, the young males and the females being both 

 alike, and of quite sober plumage. Cases such as the Bell- 

 birds {Chasviorhynchus), the Cotingas {Cotifiga, Xiphole?ia, 

 etc.), the Firebirds {Fhxnicocerais), the Cock-of-the-rock 

 {Rupicola), the Humming-birds {Trochilidce) , etc., will at once 

 occur to you. In other cases, the males and females are 

 colored equally, or almost equally, brilliantly, such as the 

 Scarlet Ibis {Eudocimiis ruber) the Macaws (Ara), the 

 Jacamars {Galbulidce), the Bill-birds {Rhatnphastcs), and 

 others, though in many of these cases the young birds of 

 both sexes are quite different in color from the adults. 



The peculiarity of tint in many of our species is well 

 worthy of notice — the pure white of the males of the Bell- 

 bird {Chasinorhynchus albus) ; the variegated grays of the 

 Giant Goatsucker {Nyctibius grandis) ; the intense green tints 

 of the Parrots {Chrysotis) ; and the rainbow-colored Tanager 

 (CalUste tatad). Sexual relations (as in the first case), and 

 protective (as in the second and third), evidently serve tc 

 explain the advantages of such coloring. 



While on the subject of coloring, it is interesting to note 

 that certain tints, in certain of our birds, can be entirely and 

 permanently changed by the application of heat. Thus the 

 purple tints on the throat, breast and body of Cotinga cayana, 

 C. cccrulca^zxidi Xipholcna pompadora, C2,vi be changed to a 

 brilliant red by exposing them to heat in such a way as to 

 affect those feathers without singeing — an indication of the 

 possibilities in nature under changing thermal conditions ! 

 Here, too, must be recalled the change produced in so many 

 of the Green Parrots by the native peoples of Guiana, who, 

 by feeding these birds on a special diet, consisting largely 



