Plumaffes of Buteo solit2iYi\x.s, 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 tibiae 
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 nnderneath till the 
almost pure /bnf£ 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. Tlie 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 in 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 ' Birds 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 tertiaries barred across both webs ; 
3d2 
