76 THE SCOTTISH NATURALIST 



information as I have indicates the continuance of poor 

 seasons for another decade, followed by a short period of 

 relatively populous ones, then many of the birds were 

 harassed into leaving. The latest phase in the history of the 

 colony is a return of the Gulls in force to these moors. The 

 number present on Auchencorth Moss on 30th May 1919 

 (a dry season) was a surprise to me. Hundreds of screaming 

 gulls were in the air, and on two "mossy" parts of the moor 

 their nests were to be seen in scores. There could scarcely 

 be less, I estimated, than 250 pairs on Auchencorth ground, 

 and beyond it there would be quite another 100 pairs. 

 From a West Linton man, who had gathered as many eggs 

 as his fishing-basket would hold, I learned that the birds 

 were present in like numbers in 191 8, but not quite on 

 the same ground. This year (4th June) they seem to me as 

 plentiful but more scattered. It is worthy of note that the 

 Black-headed Gulls began to leave the White Moss, near 

 West Linton, about 191 5, and had practically deserted it 

 by 1919.^ This probably explains the recent increase at 

 Auchencorth and the adjacent moors. 



Western section of TJireipmuir Reservoir, at the foot of 

 the Pentlands, near Balerno. The extension of Threipmuir 

 Reservoir on to the meadow beyond the pine-wood was 

 carried out about twenty-five years ago, and as the area 

 of sedges and other marsh vegetation increased in extent it 

 gradually attracted the attention of the Black-headed Gulls 

 of the neighbourhood, and in due course a colony was 

 founded. Eggs were first seen, Mr Davidson (keeper) tells 

 me, in 1905 or 1906, and for some years the colony was 

 small; recently, however, it has increased greatly. In 191 6 

 I noted it as a large colony, and in May 191 9 I set it down 

 at 250 to 300 pairs. In the latter year the keeper lifted 

 fifteen dozen fresh eggs on loth May, besides many on 

 other dates. This year (8th May 1920) the birds appear to 

 me to be no less numerous. 



^ The gullery on the White Moss, near West Linton, was a very 

 large one for twenty years. In 1897 Mr R. Godfrey spoke of it as the 

 most populous in our district. At the end of April 1902 my son thought 

 there could not be far short of 1000 pairs, and my own observation in 

 June 1904 seemed to support this estimate. According to the 

 keeper's statement the Gulls came to this Moss in 1893. 



