198 BRITISH BIRDS. 



and the eggs, five of her own and the one of the Tufted Duck, 

 cold and covered with grass (in 1906 when the Scoter 

 deserted, the eggs were also covered with grass). She did not 

 resume her sitting, but was apparently alive and well on 

 July 23rd, when I saw a female Scoter on the water a few 

 hundred yards from the nest. On the 26th I photographed 

 the nest and eggs, which latter were somewhat weathered. 

 On breaking the eggs I found that those which were fertile 

 appeared to be about half incubated. The 13th June is a 

 late date for the duck to have commenced laying, but I feel 

 pretty certain that a clutch of eggs I found on the 6th June, 

 which had disappeared by the 13th, was laid by the same 

 bird. 



Herbert Trevelyan. 



NUMBER OF EGGS LAID BY TERNS. 

 I have read with considerable interest the notes on the 

 number of eggs laid by Terns (antea, pp. 90 and 129), but I am 

 quite unable to accept Mr. Gilroy's theory that the number 

 in the clutch is regulated or in any way influenced by the food- 

 supply, especially with birds that depend almost entirely on 

 fish, small fry being particularly abundant during the 

 breeding season within the feeding radius. I think it is 

 generally agreed that climatic conditions play a very important 

 part, and must regulate to a very great extent the size of the 

 clutch. I have frequently noticed during very favourable 

 seasons normal sets predominate and abnormal sets frequently 

 occur, and apparently when food must be scarcer and far 

 more difficult to obtain, we invariably find certain species 

 laying normally large clutches. In Scandinavia the Redwing, 

 Fieldfare, Brambling, Great Grey Shrike, Lapland Bunting, 

 Red-throated Pipit, Rough-legged Buzzard, European Hawk- 

 Owl, etc., all have large broods, while the following species 

 on the average all have larger broods than is the case with 

 the same species in this country : — Chaffinch, Reed-Bunting, 

 Lesser Whitethroat, Raven, Merlin, Moorhen, Coot, Grebes, 

 etc. Colonel Feilden called attention to the large clutches 

 of the Wheatear in the Faroes, while doubtless Mr. Gilroy 

 knows that the Skylark invariably lays five in North Uist, 

 where the food-supply cannot possibly be so plentiful as in 

 the fertile rural districts in the south of England, and where 

 the normal clutch is from three to four, five being exceedingly 

 rare. Age undoubtedly must play the most important part 

 in the egg-producing powers of all birds : the fully adult 

 birds, which would in all probability predominate in a large 



