OCR Text |
Show 754 CAPT. F. W. HUTTON ON A COLLECTION OF [Dec 5, about among the trees above his head. The true Mutton-bird had not yet commenced to lay. Mr. Cheeseman also informs m e that none of the young birds were dark-coloured, but closely resembled the old ones in plumage. Mr. Bell says that the winter Mutton-bird breeds from M a y to September and that its egg is rather larger and rounder than that of the true Kermadec Mutton-bird. As all the specimens sent to m e were labelled Sunday Island, the species must occur there too, and some of them may breed later with the next variety, which is the summer Mutton-bird. Indeed this must be the case if the nestling just described really belongs to (E. neglecta. 03STRELATA NEGLECTA, variety. One adult from Sunday Island, August 1888. Length 15-5 inches, wing 11-25, tail 4*5, bid 1*2, tarsus 1*5, mid toe 1*8. The whole of the head, neck, breast, and flanks brownish grey ; darker on the back, wings, and tail. Abdomen and crissum white. Under wing-coverts brownish grey. Bill, legs, and feet as in CE. neglecta. The wings when folded extend about an inch beyond the tail. This variety is very closely allied to the typical CE. neglecta; but, in addition to the colours, it may be distinguished from it by the contour of the line of junction of the feathers with the base of the bill, which runs from the base of the nasal tubes obliquely backward to the gape, and does not descend as in the typical OI. neglecta. If this character is constant there can be no hesitation in admitting it as an incipient species ; but, unfortunately, I have only one specimen. This variety appears to be the true Mutton-bird of the settlers, which is said " to arrive in immense numbers at the end of August or early in September, and to breed all over the main island, but most abundantly towards the tops of the hills. Unlike most of the other Petrels it makes no burrow, but lays its single egg in a hollow at the root of a tree or even anywhere on the bare ground" (Cheeseman). However, it would seem, as already mentioned, that some individuals of the typical form also breed on the main island in September with the variety, for Mr. Bell sent skins of both kinds to Mr. Cheeseman, who understood him to say that both belonged to the summer Mutton-birds; but as he also sent at the same time specimens of OI. phillipi, there is considerable doubt as to what he meant. Mr. Cheeseman himself says, " I find but little difference between the two kinds (whiter and summer Mutton-birds), save that this (winter Mutton-bird) has a more distinct dark band across the breast." It seems probable that w e have here a very interesting example of the evolution of a new species by isolation due to an alteration in the time of breeding of certain individuals of Gl. neglecta. This seems to be a better explanation of the facts, as they are at present known, than the supposition that we have here merely individual |