(2237) Ixobrychus sinensis sinensis.
The Yellow Bittern.
Ardea sinensis Gmelin, Syst. Nat., i, p. 642 (1789) (China). Ardetta sinensis. Blanf. & Oates, iv, p. 401.
Vernacular names. Jun-Bogla (Hind.); Kat-Bogla (Beng.); Manual Nari (Tam., Ceylon) ; Metti-korowaka (Cing.).
Description. - Male. Upper part of head and crest black ; sides of crown showing grey; chin, throat and fore-neck pale yellowish or buffy-white, the feathers on the sides of the neck mixed pink and rufous, the longest, meeting on the back of the neck, all deep rufous; sides of the head vinous-pink; back, scapulars and innermost secondaries light brown but varying greatly, sometimes yellow-brown, sometimes grey-brown and at other times mixed chestnut, or rufous, and grey-brown; rump dark ashy; tail slaty-black; primaries, primary coverts and outer secondaries blackish; wing-coverts buff, more tawny next the back; long feathers of upper breast blackish edged with buff, generally nearly concealed by the long buff feathers of the fore-neck; flanks, axillaries and under wing-coverts white, lower breast, abdomen and under tail-coverts pale yellow-buff.
Colours of soft parts. Iris orange-yellow; bill pinkish- or yellowish-horny, the culmen darker and browner ; naked skin of face pale greenish or greenish livid; legs and feet pale flesh-colour, more yellow on the joints.
Measurements. Wing 129 to 136 mm. (once 143 mm.); tail 41 to 47 mm.; tarsus 44 to 51 mm.; culmen 52 (once 49) to 57 mm.
Female only differs in having a mesial buff line down the throat and fore-neck and in old birds even this disappears and I have frequently shot pairs of birds exactly alike in plumage.
Young birds are more rufous-brown above with broad buff fringes to all the feathers ; the mesial buff line down the throat and neck is more conspicuous; underparts more heavily streaked.
Distribution. India and Ceylon, East to South China through Burma, the Malay States and Archipelago to the Celebes. In India it is resident in Travancore and Malabar; breeds in Sind during the Bains, is very common in East Bengal, Assam and many parts of Burma, but rare in the rest of India and in the driest parts of Burma.
Nidification. The Yellow Bittern breeds throughout its range from June to September, but rather earlier than this sometimes in Sind. In Assam it is extremely common, though less so than the Chestnut Bittern, whilst its nest is so carefully hidden that it is most difficult to find, the bird sitting motionless though one passes within a few inches of it. Nest and site differ in no way from those of the Little Bittern but the eggs are smaller and in colour a very pale skim-milk green-blue. Forty eggs average 30.9 x 23.7 mm.: maxima 33.7 X 25.0 mm.; minima 27.5 x 22.2 mm.
In China Jones and "Vaughn took eggs in May and June.
Habits. This tiny Bittern is not so exclusively crepuscular or nocturnal as the Little Bittern and I have often seen it feeding by day at the edge of reeds in swamps. When noticed it creeps away quietly into the jangle, taking long, slow steps and furtively looking round to see what is happening. It feeds principally on small frogs and water insects but doubtless eats much the same variety of food as other small Bitterns.