(2099) Gygis alba monte.
THE INDIAN OCEAN WHITE TERN.
Gygis alba monte Mathews, Birds of Australia, ii, p. 443 (Nov. 1st, 1912) (Seychelles). Gygis Candida. Blanf. & Oates, iv, footnote, p. 326.
Vernacular names. None recorded.
Description. A narrow ring of feathers round the eye black remainder of plumage pure white; shafts of primaries and tail-feathers dark brown.
Colours of soft parts. Iris brown; bill black, the basal half blue; the legs and feet yellow.
Measurements. Wing 223 to 239 mm.; tail 105 to 111 mm.; tarsus 11 to 12 mm.; culmen 36 to 40 mm.
Nestling in down. Black.
Distribution. Indian Ocean, breeding in the Seychelles.
Nidification. The White Tern breeds in the Seychelles during November, laying a single egg which is deposited on a branch of a tree. There is no nest but the egg is placed either in some small hollow or ledge of a branch or on the lichen and moss with which it may be covered. Nor is an absolutely horizontal branch always selected and, so long as the egg will stay where laid, almost any spot seems good enough, at any height from ten to sixty feet. The parent birds, both sexes, sit very close, refusing to move off their eggs until almost touched and if there is any wind are still more loth to leave. The young ones remain on the branches until fledged, looking like black balls of fluff as big as their snow-white parents. The eggs are quite unlike those of any other Gull or Tern. In shape they are very broad ellipses, whilst the ground-colour varies from almost dead grey-white to very pale greyish-pink, buff or dull yellow. The markings vary considerably. The primary ones consist of blotches, scriggly lines or spots of black, or some shade of reddish-brown with secondary blotches and spots of grey. The markings of both kinds are distributed freely over the whole egg but in many are more numerous at one end, in a few cases forming ill-defined caps or rings. Forty eggs average 40.2 x 30.7 mm.: maxima 44.5 X 31.1 and 42.0 x 32.1 mm.; minima 35.9 x 29.3 and 39.7 x 28.1 mm.
Habits. Similar to those of the Noddies, but faster, lighter and more elegant on the wing.
A specimen of this bird obtained in the Bay of Bengal is in the Leyden Museum. Hume thinks he twice saw this species in Indian Seas, whilst in 1897, when on my way home to England, a White Tern twice came about our steamer between Madras and Colombo.