INSTINCT AND INTELLIGENCE IN BIRDS 



87 



chips, carry them to the chosen site, and go through the instinctive 

 moulding and turning movements in the most approved and character- 

 istic manner. The male even mounted the female, and was borne on 

 her back like a circus-rider, in his evident attempt to perform an act 



Fig. 21. /Ekie of Eagle occupied Fifteen Yeaes, and nearly twice as tall as 

 broad ; the predecessor of the nest shown In Fig. 20 In dead sycamore, three and 

 one half feet in diameter at base ; top of nest 77 feet from ground. 



which is usually necessary. In this case, however, eggs were not des- 

 tined to appear, and the new nest was eventually given up. This 

 sporadic attempt at nest-building, while there are still chicks to be 

 nursed, illustrates what we have described as the conflict of opposing 

 instincts. 



At the beginning of the breeding season in the gull, old nests are 

 frequently reclaimed, and possibly by the same birds, though this has 

 not been determined, or a new site is chosen, and a new nest built. 

 If an addled egg is left after the others have hatched, " repairs " to 

 the nest are frequently undertaken, and the old egg is either incubated 

 for several days longer or it is buried out of sight. A pair of gulls, 

 which was watched from the tent, had a single chick, and this one 



