"Young.--Differs from the adult in having no elongated plumes, and being everywhere browner; feathers of the upper surface tipped with a rufous or sandy-buff spot; feathers of neck and under parts vinaceous-rufous with mesial streaks of white, the whole under surface very thickly streaked." (Sharpe.)
This is the very largest of Philippine herons and it may be known at once by its almost uniform slate-gray color. In a male from Bohol the iris was red; bill black, with some yellow on lower mandible; legs and nails blackish brown. Wing, 440; tail, 170; culmen from frontal feathers, 180; tarsus, 164; middle toe with claw, 126; hind toe with claw, 77.
Of medium size; plumage all white and with long dorsal plumes during the breeding season; primaries exceed the secondaries by length of hind toe with claw; legs and feet black; toes long, culmen much less than middle toe without claw.
Ardea intermedia Wagler, Isis (1829), 659. Mesophoyx intermedia Sharpe, Cat. Birds Brit. Mus. (1898), 26, 85; Hand-List (1899), 1, 195; Oates, Cat. Birds' Eggs (1902), 2, 115; McGregor and Worcester, Hand-List (1906), 32.
Bohol (Steere Exp.); Calayan (McGregor); Mindanao (Everett); Mindoro (Bourns & Worcester); Palawan (Whitehead); Samar (Steere Exp.). Indian Peninsula, Malayan Archipelago, China, Japan.
"Adult male in breeding plumage.--Pure white above and below; the head crested, but having no drooping plumes; long ornamental plumes of back immensely developed, being 430 mm. in length; feathers on the fore neck beautifully developed, 200 mm. long, the webs entirely broken up; bare part of tibia entirely black like the tarsi and toes. 'Bill black, facial skin green; iris yellow; feet and toes black.' (Oates.) Length, about 208; culmen, 74; wing, 317; tail, 137; tarsus, 114; middle toe with claw, 99.
"Adult female.--Similar to the male, but the ornamental plumes not so much developed.
"Adults in winter plumage.--Pure white, but losing the ornamental plumes altogether. 'Bill yellow, with blackish tip.' (Oates.)
"Young.--Entirely like the adults in winter plumage; the texture of the plumage soft and downy, and devoid of ornamental plumes." (Sharpe.)
"Comparatively rare and very shy. Fairly abundant about the Laguna de Naujan in Mindoro." (Bourns and Worcester MS.)