C2 Y)\^'\Q,YiT, Moults and Plumages of Gulls and Terns. \jti 



with an extensive prenuptial moult, which acquire adult plumage 

 at the first postnuptial, and (2) the larger species, with a more 

 limited prenuptial, which acquire few if any signs of aduh plum- 

 age until the second postnuptial change. The postnuptial moult, 

 beginning directly after the breeding season, proceeds more 

 rapidly than the prenuptial, which is rather a leisurely affair, 

 beginning sometimes, especially in the case of the Gulls, as early 

 as mid-winter. Young birds regularly by an incomplete post- 

 juvenal moult pass into a first winter plumage which, among the 

 Terns, is scarcely different from the adult winter dress ; among 

 the smaller Gulls it is recognizable in most species by black- 

 banded tails and dusky cubital bands, the remains of juvenal 

 dress, and among the larger Gulls it is of quite a different pattern 

 and color from the mature plumage of adults. The postjuvenal 

 moult seldom manifests itself before the end of September or 

 much later, and in the larger species proceeds so leisurely that it 

 sometimes appears to overlap the first prenuptial, beginning as 

 early as February or March. 



It is an interesting question whether young birds breed before 

 their second summer. A considerable number of immature birds 

 of different species are certainly found in summer south of their 

 breeding range, but their numbers do not seem to warrant the con- 

 clusion that all young birds do not breed the first summer. It is 

 more probable that they are the less vigorous individuals of the 

 species. They have been credited with remaining in winter 

 plumage, but this impression needs qualification, for I have ex- 

 amined, while fresh, eight specimens of the Arctic Tern {Sterna 

 paradisted) , and three of the Kittiwake Gull {Rissa tridadyld) , 

 which show clearly evidences of a recent prenuptial moult, only 

 instead of assuming nuptial dress they have reverted to the winter 

 plumage. I secured these birds on Sable Island, Nova Scotia, 

 between June 5 and 11, 1894, and dissection showed that they 

 were neither breeding nor about to do so. The Terns were of 

 course in the plumage once described as " Sterna port/andica,'" 

 and were easily distinguishable among thousands of Common, 

 Arctic and Roseate Terns already breeding, by their white fore- 

 heads, dusky cubital bands, short tails and black feet and bills. 

 Attention was often drawn to them by their single harsh croak 



