(1763) Spizaetus alboniger.
Nisaetus alboniger Blyth, J. A. S. B., xiv,p. 173 (1845) (Malacca). Spizaetus albiniger. Blanf. & Oates, iii, p. 354.
Vernacular names. None recorded.
Description. Upper parts and sides of head, crest, neck, upper back and lesser wing-coverts black ; browner on the lower back, wing-coverts and quills; primaries blackish at the tips, with a few narrow bars of blackish and with white mottlings on the bases of the inner webs below the emargination ; tail blackish-brown, a narrow pale tip and a broad grey band next to a broad black subterminal one ; lower parts white, a central black streak from the chin to the throat; the breast and upper flanks with broad black streaks; abdomen, flanks and under tail-coverts with bars of black, much broader than the white; thigh-coverts with bars of black and white about equal in breadth; under wing-coverts and axillaries black and white.
Colours of soft parts. Iris yellow; bill black, the base tinged with grey or plumbeous; cere black ; legs and feet yellow. The feathering of the tarsus extends well on to the base of the toes as in the other species of this genus.
Measurements. Wing 315 to 323 mm.; tail 217 to 242 mm.; tarsus about 84 mm.; culmen 28 to 32 mm. There are hardly any sexed skins in Museums but there cannot be much difference in size in the male and female.
Young birds are exactly like the young adults of Spizaetus n. nipalensis but have chin and cheek-stripes less developed, the black streaks on the breast broader and generally more rufous on the abdomen.
Still younger birds have the whole head, neck and upper back fulvous, except for the longer crest-feathers which are black ; the upper parts are pale brown with broad white edges ; the tail has four dark bars with intermediate paler grey-brown bars; below the plumage is pale fulvous, whiter on the throat and chin, darkest on the vent and tinder tail-coverts ; the ear-coverts and sides of the neck are generally a darker, rather more rufous, fulvous.
Distribution. From the South of Tenasserim, through the Malay Peninsula and South-West Siam to Borneo. Nidification. Nothing recorded. Habits. Those of the genus so far as is known.