DEFECTIVE CYCLES. 79 



Once he picked a straw out of the nest and carried it away. The record was normal for the 

 remainder of the day. 



Mar. 6. The male did not offer to go on the nest during the entire day. The female 

 was off and on many times. She was frequently led to resign by the male coming to the 

 box, but she was mistaken as to his purpose. He paid no attention to the nest when she 

 left it, except to tear it to pieces and walk roughly over the eggs. I removed the eggs early 

 in the forenoon to another pair, and gave him a pair of old discarded eggs. The female 

 kept on the nest all day, except for short intervals when she left expecting the male to do 

 his part. Several times the male visited the nest and tried to satisfy his passion on his mate, 

 thus forcing her off the nest. 



This strange and sudden desertion of the nest by the male was accompanied by attempts 

 to get out of the pen, by flying again and again against the window and then against the 

 wire screen. He appeared extremely restless, and his whole behavior was very different 

 from what it had been hitherto. 



Is it possible that too rich food brought his course of incubation to a premature close 

 and stimulated him to renew the cycle of his paternal functions? Is it the same cause in 

 the case of the crested pigeons which leads them to desert their nest after 6 or 7 days? 

 I notice that the desertion of the nest in the latter case begins with a sexual union. When 

 this has happened the birds may keep on for a day or two in care of the nest, but gradually 

 they leave it for a longer and longer time, and in the course of two or three days they cease 

 to return to it. The union may be stimulated by too much hemp seed and (once started) 

 it brings the incubation course to an end and introduces a new cycle. 



On Mar. 8 I found that the female had broken one of the old eggs given to them and 

 I removed the other. As soon as she left the nest and began to receive the male he quieted 

 down and eagerly called her to the nest-box. This shows that he is fully prepared for a 

 new course. (R 18.) 



CRESTED-PIGEON MALE AND RING-DOVE FEMALE. 



FIRST CYCLE. 



This pair had an unusually long courting period. It covered 11 days in addition 

 to a period of unknown length which preceded the record. The incubation period 

 began on January 20, and ended on February 8, a period of 20 days. As in the 

 preceding pair (passenger X ring), the incubation activities continued over a long 

 period, in spite of a number of abnormal conditions the absence of the act of 

 laying, the absence of eggs, lack of interchange with her mate, and the solici- 

 tations of the male. The incubation, furthermore, extended over into the period 

 devoted to the care of the young, so that the latter part of the activity continued 

 also in spite of the absence of the young, and during a period of need for feeding 

 them. Evidently the incubating impulse did not even arise in the case of the male. 



On Jan. 9 I expected the female (GF 1} of this pair to lay for the first time. I found 

 her on her nest at 3 h 50 p. m. and kept watch in order to get the exact time. She behaved 

 as if she was just ready to lay. She came off the nest at 4 h 30 m , flew to the floor, and then 

 took her place on the perch beside her mate until 5 h 45 m . At 5 h 45 m , after dark, she went 

 to the nest-box and sat quietly until 7 h 50 m , when she got up on the edge of the nest-box 

 and soon stepped upon the perch close by. She remained on the perch all night, returning 

 to the nest early next morning. She evidently went through the preliminaries to laying, 

 but was a little premature in her actions. 



Jan. 10. To my surprise the female pays little attention to her nest, at the time 

 she should take the nest and lay. She was on the nest early in the morning and during 



