2o8 THE BIRDS OF THE BRITISH ISLES. 



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bird shows remarkable sense. I saw one Gull drop its cockle 

 ten times in one spot, and another only smashed it after 

 eleven attempts ; in both cases the molluscs were dropped on 

 sand ; yet three different birds, after a first unsuccessful attempt 

 on sand, deliberately carried their cockles to above some flat 

 sandstone rocks and dropped them. These rocks were littered 

 with broken shells. 



The flight of the Common Gull is leisurely, its wing-beats 

 more deliberate than those of the Black-head. It sails fre- 

 quently, careening so as to benefit from every air current, and 

 adjusting iis balance with its tail. It swims gracefully, but 

 only submerges itself when excited by the pursuit of a shoal of 

 fish. Its usual calls are a sharp kak^ kak, kak, an alarm note 

 or threat, and a resounding kyah, but it has other calls difficult 

 to express and impossible to interpret. One note, however, is 

 either a love signal or challenge, but may be heard long before 

 the bird leaves our shores ; the head is lowered and then raised, 

 the bill pointed upwards, and, with the mandibles wide open, the 

 bird gives vent to a series of clarion, laughing cries. 



At all seasons the Common Gull is gregarious, and though 

 isolated pairs are met with in inland locaHties, the nests are 

 usually in a colony on a cliff, an island either at sea or on a 

 loch, or on the moors, even at over 2000 feet altitude. The 

 nest is at times a scratching in short turf or on a ledge, but 

 is often in thick heather or coarse herbage (Plate 90) ; it is 

 seldom lined, but usually walled with grasses, ling, or rushes, 

 and on the cliffs seaweed. Three is the normal number of 

 eggs, which vary greatly in ground colour and markings ; a 

 usual type is olive or buff, sparsely spotted with black (Plate 80), 

 but I have seen unspotted blue eggs. Incubation begins in 

 May, and the first young leave the colony as a rule in July. 

 The nestlings, which like other juvenile gulls vary greatly, are 

 greyish buff, mottled and streaked with black or brown. 



The adult bird in summer has pale grey back and wings, and, 



