1212. Spizaetus limnaetus.
The Changeable Hawk-Eagle.
Falco limnaeetus, Horsfield, Tr. Linn. Soc. xiii, p. 138 (1821): Temm. Pl. Col. pl. 134. Falco caligatus, Raffles, Tr. Linn. Soc. xiii, p. 278 (1822). Falco niveus, Temm. Pl. Col. pl. 127 (1823). Limnaetus horsfieldi, Vigors, Mem. Baffl. p. 649 (1830) ; Gurney, Ibis, 1877, p. 428 ; Hume, S. F. vi, p. 11, note; id. Cat. no. 34 A ; Cripps, S. F. vii, p. 246. Nisaetus pallidus, Hodgs. J. A. S. B. vi, p. 361 (1837), descr. nulla. Spizaetus limnaetus, Blyth, Cat. p. 24; Horsf. & M. Cat. i, p. 32; Sharpe, Cat. B. M. i, p. 272 ; Blyth, & Wald. Birds Burm. p. 63; Hume Sf Dav. S. F. vi, p. 11; Oates, B. B. ii, p. 192 ; id. in Hume's N. §: E. 2nd ed. iii, p. 149. Spizaetus caligatus, Horsf. & M. Cat. i, p. 33; Blyth, Ibis, 1866, p. 241; Hume, Rough Notes, p. 198; Hume & Oates, S. F. iii, p. 26; Armstrong, S. F. iv, p. 297; Hume & Inglis, S. F. v, p. 9. Falco limnaetus, Bernstein, J. f. Orn. 1860, p. 419. Limnaetus niveus, Jerdon, B. I. i, p. 70 ; Godw.-Aust. J. A. S. B. xxxix, pt. 2, p. 93. Spizaetus andamanensis, Tytler, P. A. S. B. 1865, p. 112; Beavan, Ibis, 1867, p. 315; Hume, Rough Notes, p. 203; Ball, S. F. i, p. 52 ; Hume, S. F. ii, p. 142; iv, p. 280. Limnaetus caligatus, Jerdon, Ibis, 1871, p. 246 ; Gurney, Ibis, 1877, p. 425 ; Hume, S. F. vii, p. 198; id. Cat. no. 34; Bingham, S. F. ix, p. 143; Hume, S. F. xi, p. 10. Limnaetus andamanensis, Walden, Ibis, 1874, p. 127; Hume, Cat. no. 34 bis.
Sadal, H., Bengal; Morhaita, Garhwal.
Coloration. Very similar to that of S. cirrhatus, from which the present bird differs in having no crest or only a rudimentary one; the plumage is generally paler, the lower parts in young birds much more commonly pure white, and the head white with brown shaft-stripes; whilst even in the oldest birds some traces of white bars remain on the brown feathers of the thighs, vent, and lower tail-coverts; and the gular and moustachial stripes and the dark spots on the breast are better defined. Soft parts and measurements as in S. cirrhatus, and the feathers of the tarsus, as in that species, terminate at or above the division of the toes, and do not cover the base of the middle toe as in S. nepalensis.
Besides the ordinary form, there is a dark or melanistic variety, the original Falco limnaetus (or Limnaetus horsfieldi). This is blackish brown throughout, the basal half of the inner webs of the quills and the lower surface of the rectrices near their base being grey. Some specimens are chocolate-brown, not blackish, and in these the three black gular stripes—one median, and one at each side—can be recognized. The bill and cere are black. This dark form, at first supposed to be distinct, has for many years by most writers been regarded as identical with the ordinary variety (& caligatus v. niveus), and has been by several naturalists described as the old bird. But in several cases blackish nestlings, the produce of dark-coloured parents, have been observed, in Java by Schlegel and Bernstein, and in Bengal by Cripps ; and whilst it is certain that the dark Coloration is not due to age, the question has again arisen whether this dark S. limnaetus is not a distinct species. Both Gurney and Hume are doubtful as to whether the two phases belong to the same species; but until further evidence is forthcoming I prefer to keep the two together, as in Buzzards a similar melanistic phase is common. Whitehead, in Labuan, shot from the nest a female in ordinary plumage, paired with a black male (Ibis, 1889, p. 71).
A small insular form (S. andamanensis, Tytler) occurs in the Andaman Islands, precisely resembling ordinary S. limnaetus in everything except size (length in a female 25.5 ; tail 10.25; wing 14.25; tarsus 3.6).
Distribution. Throughout the sub-Himalayan forests as far west as Kumaun and probably to Kashmir; throughout Lower and Eastern Bengal, Assam, and the Burmese countries, the Malay Peninsula, Sumatra, Borneo, Java, and Flores. The dark variety has been found in Lower Bengal, the Malay Peninsula, Sumatra, Borneo, and Java. The supposed occurrence of S. limnaetus in the Indian Peninsula is doubtless due to specimens of S. cirrhatus in moult having been mistaken for it.
Habits, &c Precisely similar to those of S. cirrhatus, except that the breeding-season is from February to June, chiefly in April and May.