NOTES 309 



sidering that the weather was fine throughout the month of July. 

 The failure of the food supply of these interesting birds is a subject 

 of a very speculative nature. It has been suggested, for instance, 

 that the presence in these waters of immense shoals of mackerel, 

 together with unusual quantities of whiting and the ubiquitous 

 'dog,' may have been an important factor in diminishing the supply 

 of sand-eel (the principal food of the young Tern), and this seems to 

 be a very reasonable supposition. The fact however remains that not 

 a single young bird has been observed on the wing this season. The 

 Terns — which seem to be all of the ' Arctic ' variety — were present 

 this year in increased number, having evidently found ' The Rock ' 

 a safe nesting place during the last few years." — John S. Tulloch, 

 Lerwick. 



Spring Moult of Gulls. — I have been cognisant for many 

 years of the fact that, so far as I know, all Gulls moult in spring, 

 but I should like to give the credit to the man who first fully 

 went into the moult of the Black-headed, Common, and Kittiwake 

 Gulls — viz., Blake-Knox in the Zoologist, 1866-68. He was the 

 first to record in detail the sequences of plumages in these birds, 

 and recorded their spring moult, and he was, I consider, far ahead 

 of his time on this subject. His Letters on Ornithology, which 

 seem to be much overlooked, can profitably be read to this day. 

 They deal with moults, plumages, and habits of sea-birds, though 

 I do not think all his deductions on moults are accurate. Besides 

 recording the spring moult of Gulls, he was the first, so far as 

 I am aware, to point out that these Gulls in the second winter 

 and summer may be distinguished from adults by the dark markings 

 on the primary coverts and bastard wing, and he says that 

 they do not breed in this plumage, thus accounting for the apparently 

 adult birds which are seen during the breeding season away from 

 breeding colonies. This appears to me a likely explanation, and 

 though I believe occasionally Black-headed Gulls one year old 

 will breed, the vast majority at this age, and possibly also at 

 two years old, do not. From the result of "ringing" this species 

 it has been recorded {British Birds (mag.), vol. viii., p. 209) that 

 birds one or two years old have been found dead in a breeding 

 colony, but this of itself cannot be taken as proof of breeding 

 at this age, though it is of course suggestive. All doubts might 

 have been laid aside had the bodies been competently examined. 

 There is no guide from "ringing" in the case of the Common 

 and Kittiwake Gulls, and we are still in the dark as to whether 

 Blake-Knox is correct in his surmises regarding non-breeding birds 



