The Summer Birds of Shetland. 559 



inland district, wliere this gull is most abundant, is the net- 

 work of lochs lying to the south of Melby, in the parishes of 

 Walls and Nesting. On these lochs, including the loch of 

 Collaster (250 pairs), there are fully 600 pairs. Hewitson 

 fell into tlie error of describing the Collaster gull as the 

 greater black-back, but that bird never bred there, nor does 

 it on any of the lochs of Walls. On the island of ISToss there 

 is a colony of L. fuscus nesting on the ground among some 

 peat hags. At the date of my visit (17th June) there were 

 only 50 or 60 pairs, and at that late date I saw several nests 

 containing fresh eggs, but the people at ISToss Ferry said that 

 earlier in the season they were " in hundreds." They had 

 doubtless left in despair of getting any eggs hatched. 



62. Herring Gull {Larus argentatus), (White Maa). — 

 Exceeding abundant. Every precipitous headland is sure to 

 be occupied by a colony of these handsome birds. On the 

 island of ISToss they are very numerous. I estimated them at 

 upwards of 1000 pairs, and from their habit of nesting on the 

 ledges of the cliffs, and on the almost perpendicular grass 

 slope to the east of the N'oup, they do not suffer so much 

 persecution as the lesser black-backs on the turf inland. 



63. Greater Black-backed Gull {Larus marinus), (Swabie, 

 Baagie). — Single pairs of these magnificent gulls may be seen 

 at many parts of the coasts. A favourite site for the nest is 

 the flat grassy summit of some tall stack, often entirely in- 

 accessible. Frequently the stack is shared with the two 

 smaller species— ^/wscits and argentatus ; all three getting on 

 pretty well together as a rule, though marimis is rather in- 

 clined to bully. The largest colony of these birds in Britain 

 is that situated on the Holm of Noss. The Holm is a 

 detached portion of the island of Noss, and is about 200 feet 

 high, and quite inaccessible since the '* cradle " was removed 

 a few years after Professor Wilson's visit in 1841, so graphi- 

 cally described by the genial " Christopher " in his " Voyage." 

 It is about 1 J acres in extent, and the chasm between is about 

 50 yards across. On approaching the edge of the cliff, the 

 whole colony rises on the wing at once, and an accurate 

 estimate of their numbers is rather difficult to take, but I 

 came to the conclusion there cannot be less than 250 pairs 

 of these huge birds (5 J feet in extent of wing) at this place. 



