Buceros mindanensis Tweeddale, Proc. Zool. Soc. (1877), 543;
Challenger Report, Zool. (1881), 2, pt. 8, pl. 3.
Hydrocorax mindanensis Grant, Cat. Birds Brit. Mus. (1892), 17,
359; Sharpe, Hand-List (1900), 2, 64; McGregor and Worcester,
Hand-List (1906), 55.
Basilan (Everett, Steere Exp., Bourns & Worcester, McGregor);
Mindanao (Murray, Everett, Koch & Schadenberg, Steere Exp.,
Bourns & Worcester, Goodfellow, Celestino).
Adult.--Plumage as in H. hydrocorax but casque much narrower and bill
with distal two-thirds white. "Naked skin round eye sooty black,
yellow just before the eye, gular skin yellow; iris light yellow
(light green in living bird); feet coral-red; nails dark brownish
gray." (Everett.) Length of male, about 915; wing, 390; tail, 300;
bill from nostril, 155; greatest length of casque, 136; greatest
width of casque, 42; tarsus, 52. Length of female, 863; wing, 365;
tail, 290; bill from nostril, 136; greatest length of casque, 124;
greatest width of casque, 39; tarsus, 48.
"Young.--Upper part of head and cheeks black; feathers on chin and
breast white, blackish gray at base; rest of head, neck, rump,
belly, flanks, and tail-coverts white mixed with rufous; back,
upper wing-coverts, scapulars, and outer secondaries brown, the
three latter widely tipped, and the last named also widely margined
on both webs with white; rest of secondaries and primaries blackish
brown, with a white margin on the outer web, gradually increasing in
width on the outer secondaries; under wing-coverts brownish buff;
middle feathers of tail have basal two-thirds brown, and the rest
the basal half dull chestnut; the remainder of the feathers white;
casque rudimentary. Bill black, yellowish at the tip; naked skin round
eye and on gular region yellow; legs gray-green (in skin)." (Grant.)
"Habits like those of H. semigaleatus. Eyes yellow to brown in female,
light bluish gray in male; legs and feet red; bill scarlet on basal
half, rest yellowish white; bill of young birds black. A male measures
927 in length; wing, 393; tail, 312; tarsus, 54; middle toe with claw,
66." (Bourns and Worcester MS.)