(1994) Megapodius nicobariensis nicobariensis Blyth.
THE NICOBAR MEGAPODE.
Megapodius nicobariensis nicobariensis, Fauna B. I., Birds, 2nd ed, vol. v, p. 437.
This extraordinary bird is found in all the islands of the Nicobars except Choura and Car Nicobar. Butler obtained them in Battye Malve, while Hume saw traces of their mounds on Table Island from which, however, they now seem to have completely disappeared. The birds of the Great Nicobar and Little Nicobar are of the next following race.
The Megapodes frequent the dense forest growing a little above high-water mark along the shores of, nearly all the islands of the group, never leaving it during the day bat feeding on the shores during the night.
Davison writes of these birds Stray Feathers, ii, pp. 276, 499):— “The Megapode never wanders from the sea-shore, and throughout the day keeps to the thickest jungle, a hundred yards or so above high-water mark. It never, so far as I observed, emerged on to the open grass hills which form so conspicuous a feature in so many of the Nicobars, but throughout the day hugged the belt of the more or less dense jungle that in most places, along the whole coast-line, supervenes abruptly on the white coral beach.”
As regards the nidification, it is impossible to improve on the accounts given, by Davison, together with Hume’s comments thereon. The former notes :—“I have seen a great many mounds of this bird ; usually they are placed close to the shore, but in Bompoka and in Katchall I saw two mounds some way inland in the forest ; they were composed of dry leaves, sticks etc., mixed with earth, and were very small compared with others near the sea-coast, not being above three feet high and 12 or 14 feet in circumference ; those built near the coast are composed principally of sand, mixed with rubbish, and varied greatly in size but average about 5 feet high and 30 feet in circumference, but I met with one exceptionally large one on the island of Trinkut, which must have been at least 8 feet high and quite 60 feet in circumference, It was apparently a very old one, for from near its centre grew a tree about 6 feet in diameter, whose roots penetrated the mound in all directions to within a foot of its summit, some of them being nearly as thick as a man’s wrist ; I had the mound dug away almost to the level of the sur-rounding land, but only got three eggs from it, one quite fresh and two which had the chicks somewhat developed.
“Off this mound I shot a Megapode which had obviously just laid an egg ; I dissected it, and from a careful examination it would seem that the eggs are laid at long intervals, for the largest egg in the ovary was only the size of a large pea and the next in size about the size of a small pea.
“ The eggs are usually buried to 4 feet deep, and how the young manage to extricate themselves from the superincumbent mass of soil and rubbish is a mystery.
“The surface soil of the mounds only is clay ; at about a foot from the surface the sand seems slightly damp and cold, but as the depth increases the sand gets damper but at the same time increases in warmth.”
Commenting on this Hume writes :—“ I saw a considerable number of these mounds. It appears to me that the birds first collected a heap of leaves, cocoanuts, and other vegetable matter, and then scraped together sand which they threw over the heap, so as not only to fill in all interstices, but to cover everything with a foot of pure sand, which consists principally of triturated coral and shells. After a certain period, whether yearly or not of course I cannot say, the birds scrape away the covering sand-layer from about the upper three-fourths of the mound, cover the whole of it over with vegetable matter, and then cover it over again with sand. In the large mound, an old one into which I cut a narrow section from centre to margin, this arrangement was very perceptible ; in it I thought I could trace, by the more or less wedge-shaped portions of pure sand along the base, the remnants of successive outer coverings of sand, the basal portions of which have never been removed, ten or perhaps eleven successive renovations of the mound ; even the central portion was perfectly cool. The vegetable matter had in great part disappeared, leaving only the hard woody portions behind, but showing where it had been by the discoloration, of the sand. The decay of the vegetable matter and the bird’s habit of not removing the basal portion of the sandy covering at each renovation explain why the mounds increase so much more in radius than in height.
“A small mound contained a much greater mass of vegetable matter and was sensibly warm inside. I believe that the bird depends for the hatching of its eggs solely on the warmth generated by chemical action. The succulent decaying vegetation, constant moisture, and finely triturated lime, all combined in a huge heap, will account for a considerable degree of artificial heat.”
Davison thought that only one pair of birds used each mound but Hume thought otherwise, as on one occasion twenty eggs were taken from the same heap and the Nicobarese told Hume that after one pair had started a heap the birds hatched from it returned to it to lay.
As Hume once obtained an egg on a mound, the hole for its intern¬ment still uncompleted, it is evident the bird first lays the egg on the mound and then scratches out the deep hole into which it is dropped, after which the hole is filled in again.
We do not know yet whether the old birds pay any attention to the eggs after deposition or to the chicks when hatched. Butler says (Journ, Bomb. Nat. Hist. Soc. vol. xii, p. 689, 1899) that the young find their way out of the mound unaided. “For one thing the birds could never know when to dig down to save a newly hatched young one from suffocating ; further, the eggs can be hatched by packing them in a box in the material of the mound in which they are found, and Mr. E. H. Man, who hatched a chick on his verandah by this means, told me that it not only extricated itself from the sand, but flew up on the verandah railing directly it was approached.”
Eggs seem to have been taken at various odd times, so it is difficult to suggest what is the breeding season. Possibly it is more or less all the year round, the egga being laid at long intervals which may run from tell to twenty days. Again, though eggs have been hatched in houses by various people, there is nothing on record as to the period of incubation. Judging from examinations made of the ovaries and from the fact, that Hume found twenty eggs in a mound in various stages of incubation, it would appear that a hen lays four or five eggs only hut, at present, this is little more than speculation.
The eggs are enormous for the size of the bird and are in shape long ellipses. The texture is smooth when fresh but often soon becomes flaky, looking as if the surface-colour was coming off in flakes. The grain is soft, rather porous and, for the size of the eggs, the shell is brittle. Newly laid eggs are a really wonderful brick- pink, rosy pink or salmon-pink ; this gradually changes to a dull buff or ochre-brown, often much flecked with white and, eventually, the eggs become a uniform dull white.
Eighty-four eggs average 82.6 x 52.3 mm. : maxima 85.5 x 50.3 and 82.0 x 57.1 mm. ; minima 76.4 x 49.0 and 81.0 x 46.2 mm.
The chicks hatch out fully fledged and at Once join their fellows in the forest, where one sees flocks consisting of birds of all ages.
Whether these birds are monogamous, bigamous or polyandrous there is no evidence and, possibly, they are quite promiscuous.
1994. Megapodius nicobariensis nicobariensis
(1994) Megapodius nicobariensis nicobariensis Blyth.