50 Proceedings of the Royal Physical Society. 



therefore rather a surprise to me when in 1896 Messrs 

 W. Eagle Clarke and T. G. Laidlaw reported, that on 13th 

 June they had found between 20 and 30 pairs of Lesser 

 Black-backs nesting on the Eock, and not more than 6 to 8 

 pairs of Herring Gulls.^ In 1897 the Black-backs were 

 again present in force ; on 12th June I estimated them at 

 not less than 25 to 30 pairs, and found quite a number of 

 their nests. The Herring Gull was represented by 2 or 3 

 pairs only. On 24th June 1899, however, when my next 

 visit was made, I found the old proportions restored — there 

 were 15 to 20 pairs of L. argentatus, but not more than 4 

 pairs of L.ficscus could be detected. And so matters stood, 

 I was told, at the beginning of the nesting season of 1901, 

 the year the erection of the lighthouse was begun ; but 

 when I was on the island with the Berwickshire ISTaturalists' 

 Club on 19th June, very few of the larger gulls remained, 

 the majority having been scared away by the workmen. 

 The establishment of a lighthouse on the Bass probably 

 means its gradual desertion by these gulls, which, nesting 

 as they do on the grassy top, are now liable to continual 

 disturbance. There seemed to be very few about the Eock 

 last summer — from the deck of the steamer I could make 

 out only 3 or 4 Herring Gulls and a single Lesser Black- 

 back flying around. [1905, If ay 27. — Landed on the Bass 

 to-day: found just two pairs of L.fuscus nesting, and 15 to 

 18 pairs of argentatus. — W. E.] 



All the evidence I have been able to gather on the 

 subject having now been given, what conclusions can be 

 drawn from it ? It clearly proves two things, namely — 

 (1) that the naturalists who visited the Bass during the 

 first half of last century were unanimous in regarding the 

 Black-backs that then bred there as belonging to the 

 greater species, Lams niarinus; and (2) that since about 

 1860, however, the lesser species, L. fiiscus, alone has been 

 ascertained to nest there. 



1 The Lesser Black-backed Gull is included among the birds breediog 

 on the Bass in an article by Mr Eagle Clarke in Pollock's "Dictionary o( 

 the Forth," 1891, but he had not, he tells me, personally visited the Rock 

 at that time. 



