Plumages o/Buteo solitarius. 391 



it would be contrary to the general law in American Hawks, 

 in which, if I am not mistaken, the barring is better defined 

 and more constant in the adult stage. In the series of 

 specimens in the dark phase, however, the barring of the tail 

 is seen to be more of an individual character. In most, 

 though not all, of the adults the barring is well defined. 

 So it is also in most of the juveniles, but in one, the 

 youngest, perliaps, of the series, it is scarcely indicated 

 at all, and the same remark holds good of two individuals in 

 an intermediate stage. 



It is perhaps idle to speculate as to the origin and 

 significance of these two very different phases of plumage. 

 As, however, the dark phase so largely predominates, at 

 least on the rainy and windward side of the island, it has 

 occurred to the writer that the progenitors of this Hawk, 

 when they first came to the island, may have been light- 

 coloured ; and that now, after a long residence, the bird 

 is in process of undergoing transformation into an almost 

 black form. 



In this connexion it is noticeable that white is almost 

 entirely absent from Hawaiian birds, the majority of which 

 incline strongly towards greens and yellows, with a minority 

 which are clad in red and black. Chasiempis alone of the 

 woodland birds exhibits much white in its plumage, and 

 even this bird has less white and is of a deeper and more 

 lustrous brown in the rainy regions of Hawaii than in the 

 drier districts, there being, indeed, two forms or colour- 

 varieties *. 



The feathering of most of the island forms, especially of the 

 Drepanidida, which form the bulk of the indigenous birds 

 both in individuals and species, is exceedingly abundant and 

 compact, and is possessed of deep and lustrous tints, all 

 of which are indicative of a cool and rainy climate, that 

 necessitates a warm covering and confers a rich, though by 

 no means necessarily bright or gaudy, coloration. 



It is to be remembered in this connexion, hoAvever, that 

 there are at least two American Hawks, Buteo swainsoni and 



* A discussion in detail of these colour-varieties will be found in a 

 paper by the author in a recent issue of ' The Auk.' 



