COMMON AND ARCTIC-TERNS 87 



shaped hollow in the ground, and adding the lining. The latter, 

 as we have seen, may be omitted. In order to make the hollow, 

 the bird pushes its breast into the ground and turns slowly round, 

 using its legs at the same time to scrape out the sand, gravel, 

 or soil. I have often seen birds of both species engaged in this 

 work. They are easily recognised even at a distance by their elevated 

 white tails, which look as if they were planted in the ground. Four or 

 five or more scrapes are made before the final selection is made. In 

 the case of both species, again, the operation is often accompanied by 

 the posturing already described in connection with the feeding of the 

 hen by the cock. While one bird is turning round and round, the 

 other may be seen standing head up, tail up, wings part spread, in an 

 attitude of condescending attention. When the first bird steps out of 

 the scrape, the other patters up to it, eyes it a second, and steps in 

 and proceeds to rotate. The posture is assumed by both sexes, when, 

 that is, they are interested. One will occasionally stand idly by while 

 the other is busy. The working bird not infrequently pecks in a 

 somewhat spasmodic fashion at bits of sand or other objects within 

 reach, as it rotates, and throws them down by its flanks. On one 

 occasion I saw a common-tern, presumably the male, descend with a 

 fish, strike the usual attitude, then almost immediately step into 

 a scrape and start rotating, the fish being still in his beak. His 

 mate stood by posturing. After a repetition of the performance, 

 both took flight. 



The operation of lining the nest I have not seen, but judging from 

 the usually careless appearance of the finished work, the material is 

 simply brought in the beak and dropped into place, also sometimes 

 out of place. It is no doubt subjected to the process of rotation above 

 described. 



The common-tern starts laying a little earlier than the Arctic, 

 the exact date depending upon latitude and season. It generally falls 

 towards the beginning of June, and in Scotland later. The former 

 usually lays three, and the latter two eggs. In the case of both 



