The harriers or marsh hawks are noticeable among birds of prey for their slender form, long slender legs, and slow flight. Adult birds can be easily identified but the immature specimens present considerable difficulty. Species. (Adult.) a1. Upper parts black; tail silvery gray; lower breast, abdomen, and crissum white. b1. Throat and fore breast white streaked with black. ... spilonotus (p. 211) b2. Throat and fore breast black. ... melanoleucos (p. 214) a2. Upper parts dark brown; tail bluish ash. ... æruginosus (p. 215) (Immature.) a1. Facial ruff complete across the throat; smaller, tarsus about 70 mm.; wing, 340 mm. ... melanoleucos (p. 214) a2. Facial ruff incomplete; tarsus about 90 mm.; wing, 400 mm. b1. Lighter; general color more rufous-brown. ... spilonotus (p. 212) b2. Darker; general color more chocolate-brown. ... æruginosus (p. 215) 173. CIRCUS SPILONOTUS Kaup. ASIATIC MARSH HAWK. Circus spilonotus Kaup, Cont. Orn. (1850), 59; Sharpe, Cat. Birds Brit. Mus. (1874), 1, 58; Hand-List (1899), 1, 245; Blanford, Fauna Brit. Ind. Bds. (1895), 3, 388; Oates, Cat. Birds' Eggs (1902), 2, 236; McGregor and Worcester, Hand-List (1906), 40. La-uin', Manila; ma-na-o', Calayan, all species of small hawks. Batan (Edmonds); Calayan (McGregor); Luzon (Heriot, Whitehead); Mindanao (Platen); Mindoro (Everett); Palawan (Whitehead, Everett); Sulu (Guillemard). Eastern Siberia; in winter to China, Indo-Burmese countries, and Malay Archipelago. Adult male.--Above black, nape and hind neck narrowly streaked with white; feathers of lower back and rump tipped with ashy gray or white; sides of head and ear-coverts black; lower parts white; chin, throat, and breast with bold black shaft-streaks; primaries black, white for basal third; alula, primary-coverts, and secondaries ashy white with blackish shafts; secondary-coverts black, more or less mixed with ashy white; under coverts and axillars white; tail ashy white; upper tail-coverts white. Iris bright yellow; legs dull yellow; cere waxy green; bill and nails black. The above specimen from Tarlac Province, Luzon, measures, 520 in length; wing, 410; tail, 230; culmen from base, 33; tarsus, 92; middle toe with claw, 63. Younger male.--Color pattern similar; upper parts brown; white streaks on head and neck more numerous; under parts white with wider streaks of reddish brown which are also present on flanks and abdomen; primaries black, some of them barred with ashy white; wing-coverts brown with less white than the adult; primary-coverts and alula ashy white but with blackish brown bars; under wing-coverts white, streaked with blackish brown; axillars white, streaked and barred with reddish brown. Length, 533; wing, 400; tail, 235; culmen from base, 32; tarsus, 80; middle toe with claw, 61.