Vol. XVII 

 1917 



] Alexander, White-winged Black Terns in W.A. QQ 



In this connection I may point out that the presence of birds 

 in full adult plumage in Western Australia suggests that the 

 New Zealand and Cape York records, which Mathews does not 

 accept, may be genuine. 



(2) Birds in intermediate plumage. — Probably 80 per cent, of 

 the birds were in this plumage. The head and body were white, 

 with black patches, varying in amount to some extent on different 

 individuals, but not as much as one would expect if the birds were 

 really in transition from winter to summer plumage. Moreover, 

 the birds did not appear as a whole to become any darker during 

 the month during which I frequently saw them, and this just at 

 the time of year when one would suppose they would be acquiring 

 their breeding-plumage (April and May). Judging from their 

 sexual organs, these birds were all immature. The wings were 

 grey, with a white patch on the shoulder, beneath with a large 

 black patch, as already mentioned ; the tail pure white ; bill black ; 

 feet red. 



(3) One specimen obtained was like the above in every respect 

 except that the tail was grey. It is stated by Mathews that the 

 females have grey tails, the males white. All the birds of group 

 (2), both males and females, obtained by us had white tails, 

 except this one specimen. The British Museum Catalogue says 

 that this species is distinguished by its white tail. 



(4) Birds in immature plumage. — About 20 per cent., or perhaps 

 more, of the birds agreed with the others in size, colour, and shape 

 of bill and feet and proportionate lengths of quill-feathers. Their 

 plumage was, however, quite different. They were grey above, 

 with brownish mottlings on the feathers of the head and wings ; 



■_ tail grey ; under parts, including under surface of wings, pure 

 white ; feet red ; bill black. It is only owing to their structural 

 similarity and their constant association with the other birds 

 that I regard them as individuals of the same species. Almost 

 certainly they are in first year's plumage. 



In my opinion the first year's plumage is (4), the second year's 

 plumage (2), and the adult in summer plumage (i). I conclude 

 that the birds that visited Western Australia were almost all 

 immature, and that the few adults among them had already 

 assumed their summer plumage by April, when they reached us. 

 The bird described under (3) I suggest was a second-year bird, 

 which had exceptionally retained the first-year coloration of the 

 tail. These suggestions are made with much diffidence, as orni- 

 thologists who have had the opportunity of examining numerous 

 skins from all parts of the world have reached different con- 

 clusions. I would point out that many members of the family 

 Laridce have two distinct immature plumages before reaching the 

 adult form, though I am not sure whether this is the case among 

 the Sternince. 



In conclusion, I should like to appsal to Australian writers 

 not to use the most inappropriate name of White-winged Tern 



