(2239) Dupetor flavicollis flavicollis.
The Black Bittern.
Ardea flavicollis Lath., Ind. Orn., ii, p. 701 (1790) (South China). Dupetor flavicollis. Blanf. & Oates, iv, p. 403.
Vernacular names. Kala-bogla (Hind.): Nal-bogla (Beng.); Ay-jan (Assam); Karu-Nari (Tam., Ceylon); Karawal Koka, Kalu Koka (Cing.); Khaira bog (Nowgang, Assam).
Description. - Male. Whole of the upper plumage and wings varying from dark slaty-grey with a blue-grey sheen to almost black lower cheek mottled buff, chestnut and black or slate; sides of neck bright ochre-yellow; chin and throat white with a line of rufous spots down the middle; fore-neck mixed with slaty-black, deep chestnut and whitish-buff; the long feathers at the base of the fore-neck dark slate with buffy-white margins ; edge of shoulder of wing mottled with white; breast, abdomen and rest of lower plumage slate-grey to brownish-black, with a few white-edged feathers on the centre of the abdomen.
Colours of soft parts. Iris golden-brown to red ; bill reddish-horny, paler and yellowish at the tip and terminal half of the lower mandible, bare skin purple, the eyelids bluer legs and feet dark brown.
Measurements. Wing, 197 to 215 mm., 196 to 204 mm.; tail 63 to 74 mm.; tarsus 61 to 70 mm.; culmen 69 to 82 mm.
Female. The female is more brown above, less slaty-grey; the abdomen is a lighter brown with more white in the centre and the breast-feathers are brown streaked with white and, generally, with some rufous markings also.
Young birds have the upper plumage and wings dark brown, each feather edged with light rufous-brown ; lower fore-neck and upper breast brownish-rufous with darker shaft-streaks and pale edges ; the crown is nearly always more black or slaty-black.
Distribution. Practically all India but only thinly scattered here and there over the greater part. It is not rare in Ceylon and is comparatively common in Malabar and Travancore. In Eastern Bengal it is common and in Assam very common and thence it ranges through Burma to China, the Malay States and islands to the Philippines and Celebes.
Nidification. Doig found these Bitterns breeding during May in Sind but elsewhere they do not commence to lay until June, whilst fresh eggs may be taken up to September. The nest is quite typical of the family but is often placed at some height above the water on cane-bushes, bushes or even bamboo clumps. Most, however, perhaps two out of three, are built among reeds supported by a mass of broken stems. The eggs are nearly always four in number, though Jones took clutches of five and three in China which were incubated; they are of the very faintest sea-green colour possible, clear when fresh but soon becoming dingy. Forty eggs average 41.6 x 31.4 mm. : maxima 45.0 X 33.5 mm.; minima 38.8 X 30.8 and 42.1 x 30.5 mm.
Habits. Very much the same as those of Ixobrychus but more entirely nocturnal. In the breeding-season it has a loud, booming note not unlike that of Botaurus but not so loud or far-reaching. Its diet is almost exclusively fish and frogs and, like the Herons, it has a curious habit of sitting motionless with head and neck stretched out straight, with bill pointing perpendicularly to the sky.