(1758) Spizaetus cirrhatus limnaetus.
THE CHANGEABLE HAWK-EAGLE.
Falco limnaetus Horsf., Trans. Linn. Soc, xiii, p. 138 (Java). Spizaetus limnaetus. Blanf. & Oates, iii, p. 351 (part.).
Vernacular names. Sadal (Beng.); Morhaita (Garhwal).
Description. Similar to S. c. cirrhatus but generally paler, especially on the underparts and with very little crest, the longest feathers seldom exceeding an inch and often being quite rudimentary. The brown of the abdomen, vent, etc., seems to be always more or less barred with rufous-white or white. In the young birds the lower parts are often pure white, entirely devoid of any spotting or barring.
Colours of soft parts as in S. c. cirrhatus.
Measurements. Wing 400 to 438 mm.; tail 240 to 267 mm.; tarsus 100 to 103 mm.; culmen 39 to 41 mm.
A melanistic form of this race is very common and is found throughout its area. In this form the whole plumage is dark brown, in some practically black and in others more a chocolate-brown. In these latter traces of dark central streaks and of barring show faintly through the brown; the base of the tail is greyish above and there is considerable white mottling on the base below. Both the melanistic and the common form have been taken from the same nest.
Distribution. The sub-Himalayan Terai from Garhwal to Eastern Bengal and Assam ; Burma and the Malay Peninsula to Borneo, Java and Sumatra.
Nidification. This fine Eagle breeds in the plains of Assam and Bengal and in the Terai and Burmese bills from the foot-hills up to some 6,000 feet but more often between 1,500 and 3,000 feet. The nest is like that of the other races but the birds nearly all select as sites trees overhanging streams. These are usually in forest but occasionally in the open and Cripps took one nest from a large tree in a market-place. The egg, one only is laid, is a greyish-white, very rarely faintly speckled with a few reddish freckles. Ten eggs average 69.8 x 51.9 mm.: maxima 72.3 X 52.0 and 70.6 x 54.0 mm.; minima 62.0 X 51.2 and 67.0 X 48.2 mm. Two abnormally large eggs taken by myself and laid by the same bird in two consecutive years measure 74.1 x 55.6 and 76.2 x 56.5 mm. Hopwood, Fielden and others found the breeding-season in Burma to be January to April and Whymper and I took eggs in India in these same months.
Habits. Those of the species.