OCR Text |
Show 322 MR. H. SAUNDERS ON THE STERCORARIINJE. [Mar. 21, that of the Antarctic Skua, it seems to me that only the want of sufficient series of both species for comparison can ever have led to their being united ; for undoubtedly the distinctness of many other birds as species is unhesitatingly acknowledged on much slighter grounds. In the examination of a large series I have never met with any northern Skua with the stout deep bill with its well-marked angle at the gonys which invariably characterizes the southern bird; and if mere colour is taken into consideration, the total absence of rufous both on the underparts, the axillaries, and the under wing-coverts serves to distinguish the Antarctic Skua at a glance. But whilst perfectly distinguishable from A catarrhactes, it presents three interesting variations in the course of its range, which I have been enabled to trace by the aid of a fine series in the British Museum. From Campbell's Island in 54° S., 168° E., up to Norfolk Island, in 29° S. (its most northern known range), past Kerguelen's Island, the Crozets, and up to the Cape of Good Hope, where Layard observed it in April, the specimens all agree in their remarkable uniformity of sooty-brown plumage, there being few, if any, striations even upon the feathers of the neck, whilst the size of some of the examples is enormous, the primaries measuring 16 and 1 7 inches from carpal joint to tips of primaries. The Falkland-Island Skuas, locally known as " Cape-Egmont Hens " and " Sea-Hens," are decidedly smaller, and the acuminate feathers of the neck and shoulders are distinctly streaked with yellowish white, although the general sooty appearance is preserved. But in three specimens obtained during the voyage of the ' Erebus' and ' Terror,' on the edge of the pack-ice, the upper parts are somewhat less dusky than in the Falkland-Island birds, and the tips of the feathers of the breast are tinted with yellowish, though the underparts of the feathers retain their sooty hue, whilst the acuminate feathers of the neck form a complete ring of yellow verging upon golden, and, by contrast with the darker colour of the crown, giving somewhat the appearance of a hood. In general dimensions this form is somewhat smaller than the preceding, and the bill is even more short and stout in proportion ; but the general characters of resemblance are preserved throughout, the under wing-coverts and axillaries being dark smoke-coloured, whilst the lighter hue of the underparts extends no further than the tips of the feathers, and may be due to climatic influences. In their somewhat bleached appearance and the closer texture of the feathers about the base of the bill, these three birds have the appearance of permanent inhabitants of inhospitable circumpolar regions, whilst the Falkland-Island birds seem to be a connecting link between this and the larger form, whose range is principally within more temperate climates, where the conditions of existence are easier. It is most probable that Bonaparte's £. madagascarensis belongs to this species, as the late Commander Spurling saw what he supposed to be a Great Skua off the Comoro Islands, and this would bring its extreme range up to about 12° S., leaving even then an interval of more than 40° of latitude between it and the most southerly known range of S. catarrhactes. Neither has true S. antarcticus been |