SEA-BIRDS AND PLOVERS. 379 



One of the nests containing three eggs had also a stone about 

 the size of an egg placed in the middle of it. A clutch of three 

 averaged 1'61 in. by 1*16 in. ; but measurements of two isolated 

 clutches are not much on which to base arguments. I did not 

 notice any nestling Terns. 



Lesser Tern (S. minuta). — Walney Island. I found one 

 colony of these birds on a part of the beach. I examined two 

 nests containing two and three eggs respectively. Both nests 

 were on the shingle, just above high-water line ; and the clutch 

 of two eggs was amongst some large pebbles, really only just 

 lying in the depression caused by the shape of the stones, 

 without any attempt at scratching out a hollow. There was no 

 kind of lining in either case, the eggs being laid on the bare 

 stones. 



Ravenglass. Here there was also a colony of Lesser Terns 

 breeding on a shingly piece of beach to the north of the 

 estuary of the Esk. I did not search for nests, but I accidentally 

 found a single egg laid on the pebbles in a small hollow just 

 above high-water mark. 



I saw no nestlings of this species. 



Black-headed Gull (Larus ridibundus). — Walney Island. 

 There are large colonies of these birds at each end of the island, 

 both on the sand-hills and on the moss. The coarse grass 

 growing on the sand-hills forms little ridges and steps on the 

 sides of the hummocks, and make a favourite resting-place for 

 the Gulls' nests, which are thus built, as it were, in terraces. 

 The dead blades of the grass give the bulk of the building 

 material that the birds require, and with it they make, as a rule, 

 a fairly substantial but shallow cup-shaped nest, resting directly 

 on the sand. Amongst the colonies on the moss there will often 

 be nests with a considerable foundation of rubbish and dead 

 sticks, varying from a few inches to a foot in height. The 

 biggest I noticed measured fully two feet across the base, and 

 was a good twelve inches high. The rule with the nests on the 

 moss was to have a foundation of sticks under the cup of grass, 

 while the method in the sand-hills was for the cup of grass to be 

 laid right on the sand without any materials underneath it. The 

 inside measurements of the nests varied from 6-7 in. diameter 

 by l£-2 in. deep. Most of them had clutches of three eggs. 



2a2 



