In young birds of both sexes the upper plumage is a more or less dark brown, inclining in some individuals to chocolate colour, and in others to black, each feather of the back, wing, and tail coverts tipped with a lighter and more rufous brown. The chin, neck, breast, thighs, and whole under plumage is more or less dull creamy white, streaked plentifully with longitudinal blotches of dark brown, which are thin and small at the neck, but become broader and bigger as they approach the lower part of the breast, dying away again towards the vent. The tail is greyish brown on the upper surface, tipped with more or less rufous white, and barred with five or six rather irregular and rather faint bands of darker brown. The under part of the tail is very faint brownish grey, barred with a somewhat darker hue of the same colour. The sides of the head and neck are dull creamy white, streaked with very small dashes and markings of dark brown. On the under side of the eyebrow, passing round the eyelids, is a patch or streak of very dark brown, and a broad streak of the same colour or of black reaches like a moustache from near the back of the upper mandible backwards for an inch. The legs, feet, cere, and eyelids vary from light blue-grey to greenish yellow and pale ochre; beak, light bluish grey, darkening to black at the tip; claws--called always by falconers "talons"--black, as in other hawks of all kinds. In the first moult the brown of the whole upper plumage is replaced by a slatey blue, each feather from the shoulders to the end of the tail barred transversely and tipped more or less distinctly with a lighter shade of blue-grey. The slate colour on the crown and side of the head, including the moustache, is of a dark hue. The under plumage, instead of being streaked longitudinally with brown, becomes at the first moult spotted and splashed with markings of dark grey, which are partly transverse and partly shaped like an arrow-head or tear-drop, especially on the throat and gorge. At each successive moult these spots and markings become more transverse and bar-like, and also narrower and more sparse on the parts nearest the chin, until in very old birds they disappear on the chin and throat, leaving a blank surface of pure creamy white. Even before the first moult the feet and legs begin to assume a yellow colour; and by the time the first moult is over, they and the cere and eyelids have changed to a more or less decided yellow, which as the bird grows old develops into a rich gold.