Plumages of Buteo solitarius. 389 



below white, the feathers of the breast and sides tinged 

 with ochraceous^ and everywhere, except on the throat and 

 belly, with brown spots and shaft-streaks ; thighs and tibise 

 faintly barred and streaked with lighter brown. 



The difference between the two stages of the light phase 

 is very great, but a series of twelve specimens shews very 

 clearly the transition from the extremely young bird 

 (probably of the first year) to the final white-headed adult 

 stage. The adult of this phase might well be called the 

 White-headed Hawk. The juvenile is truly a Brown Hawk, 

 as it was called in Cook's time. Successive seasons witness 

 the loss of the heavy brown markings underneath till the 

 almost pure buff of the adult is attained. The younger the 

 bird, the darker the head, and the purer the white of the 

 more brown-streaked under parts. The older the bird, the 

 whiter the head, the fewer and more buffy the brown 

 markings below. 



The colour of the iris corresponds to the general color- 

 ation of the individual, being very light hazel or dark brown 

 according as the bird is light or dark. 



Some excelleut illustrations of this Hawk are given in the 

 'Birds of the Hawaiian Islands' from specimens obtained 

 by Mr. Scott B. Wilson. The buff-coloured bird, however, 

 is of a deeper hue than any specimen which the writer has 

 ever seen, and the head is by no means so white as that 

 of several ia the series before him. Nor has he ever seen 

 a specimen in which the tail-markings are so entirely 

 obliterated as in the specimen figured. 



The first figure, opposite page 1 , is that of a young bird in 

 the juvenile or brown stage, and affords an excellent idea of 

 this stage of the light phase above described. Mr. Gurney, 

 as quoted in the ' i3irds of the Hawaiian Islands,^ was in 

 error in considering the brown plumage to be that of the 

 adult. 



Dark Phase. 



Adult stage. — Above blackish brown. Primaries still 

 darker ; inner webs above the notch whitish and black 

 barred ; secondaries and tortiaries barred across both webs ; 



2d2 



