110 BRITISH BIRDS. [vol. ix. 



doubt intended, but the sittijig (Julls male rushed at one 

 of the Grow.s with upraised wmgs and ])ut liini to instant 

 flight : the other Crow was also driven off. The Gull 

 contmued to incubate the egg for most of the afternoon, 

 thougli the bird left the ne.st for a short time now and 

 again and sat near. This nest eventually held three eggs. 



On another island where a blind had been erected, 

 some time was spent on May 14th watching the birds 

 ])elonging to two nests. The first nest held two eggs. 

 The Gull stood near it for some time after the boat left, 

 two Crows then came along : the bird at once covered the 

 eggs. It sat some time and then went off. returnmg again 

 shortly after. 



The second nest held one egg (eventually both these 

 ilests held three). One of the Gulls, after standing near 

 for some time after the boat left, covered the egg : it left 

 it for a minute or so, more than once, but soon returned. 

 Some time later the other bird came to the nest and 

 covered it for a few seconds. It then went off', and the 

 bird which had previously been incubating mounted it 

 and coition ensued : therefore it is evident that the 

 male was takmg a share in incubation during the laying 

 period. After a few moments a Crow Hew over once or 

 twice : the male called uneasily and then went to the 

 nest and inculcated. Later, the female went on to the 

 nest and remained until a disturbance among the Gulls 

 put her and her mate off in flight. 



On May IGth these nests were again kept under 

 observation. At the first nest one of the Gulls soon 

 commenced to incubate after quiet liad been restored ; 

 ^fter a while its mate came and uttered the '' chaHenge"" 

 call : the sitthig bird at once left and the other w alked 

 on and incubated. The nest now luld three eggs. Later 

 the bird left the nest for a short time; a Crow .settled 

 near : both CJulls at once flew up to tlie nest and one of 

 them soon went on. The Cvow walked nearer to the 

 nest, when the non-incubating bird at once flew towards 

 it and drove it off'. It was frequently noted tluit when 



