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THALASSIDROMA LEUCOGASTER, Gow.

White-bellied Storm Petrel.

Thalassidroma leucogaster, Gould in Ann. and Mag. of Nat. Hist., vol. xiii. p. 367.

 

Tus bird is about the same size asthe Thalassidroma melanogaster, but possesses two characters by which it
may at all times be distinguished from it: these are, the total absence of black down the centre of the abdo-
men, and the shortness of its toes. I encountered it very generally over the South Indian Ocean, where I have
reason to believe that it ranges over all the temperate latitudes between the Cape of Good Hope and Cape
Horn, and it is not unlikely that it may inhabit similar latitudes in the South Atlantic. It was also noticed
by His Excellency Governor Grey, who procured and transmitted specimens to the British Museum. |
killed specimens of a nearly allied species within the tropics of the South Atlantic, which differed in being
of a larger size and in having a patch of greyish white on the throat; these differences will doubtless prove
it to be a distinct species, and I mention this in order that the two birds might not be confounded by sub-
sequent voyagers or writers on the subject. I have presented a specimen of the larger species, killed by
myself at the Equator, to the British Museum, where it is always accessible for comparison and other scien-
tific purposes.

Like the 7. melanogaster, the White-bellied Storm Petrel is a fine and powerful species, fluttering over
the glassy surface of the ocean during calms with an easy butterfly-like motion of the wings, and buffeting
and breasting with equal vigour the crests of the loftiest waves of the storm; at one moment descending
into their deep troughs, and at the next rising with the utmost alertness to their highest points, apparently
from an impulse communicated as much by striking the surface of the water with its webbed feet as by the
action of the wings. Like the other members of the genus, it feeds on mollusca, the spawn of fish, and any
kind of fatty matter that may be floating on the surface of the ocean.

Head and neck deep sooty black; back greyish black, each feather margined with white ; wings and tail
black ; chest, all the under surface and the upper tail-coverts white ; bill and feet jet-black.

Some slight variation appears to exist in the extent of the sooty colouring of the neck ; in some specimens
it merely descends to the base of the throat, while in others it spreads over the chest, but never down the
centre of the abdomen.

The figures represent the birds of the natural size fluttering over the surface of the waves in a calm.

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