DEFECTIVE CYCLES. 83 



Apr. 3. The male takes his part in sitting and has, so far as I can see, fully accepted 

 the eggs. This impulse to sit has arisen gradually in the course of 6 days. 



As an experiment in mating, I to-day took away female W 1 and put female W 2 in 

 her place. W 2 is the one I first took to be a male, and she is a little lighter in weight than 

 is W 1. W 2 laid one egg on Mar. 31 and the second on Apr. 2. She is thus one day behind 

 W 1 in egg-laying. Both of the birds of the new pair, male and female, are now in the 

 beginning of the sitting period. 



When the new female (W 2) was introduced to the cage of the male at 9 h 30 m a. m. 

 the male chased her around for a time on the floor of the cage. I covered up the box in 

 which the eggs of W 1 had been laid so that the male would not try to sit. 1 After a short 

 time the male went to the opposite box and called. W 2 responded after a few moments, 

 but seemed indifferent and soon left. The male allowed her to walk about on the perch 

 and the box without attacking her. At 9 h 45 m , while sitting on the perch, the male actually 

 induced W 2 to come to him, and she put her beak in his. This looks like dispatch as 

 compared with the behavior of this male toward W 1. Shortly, however, his disposition 

 to attack returned and he drove her about, though not so violently as he did W 1. In the 

 course of the day the male modified his behavior, becoming quite affectionate and attentive. 

 The match is evidently made for good. On Apr. 9, 6 days after mating, female W 2 

 laid an egg. (C 7/15.) 



HYBRID MALE AND MOURNING-DOVE MALE. 



These birds were paired on April 8. The male hybrid unsuccessfully attempted 

 courting during a month. His lack of success was better understood later, when 

 it was learned that his consort was also a male. On May 9 the hybrid began incu- 

 bation on the floor of the cage and sat steadily night and day. He was given eggs 

 on the 15th and accepted them. He persisted in the incubation for a week longer, 

 or until he and his consort were transferred to a cage out of doors. This hybrid 

 had never been mated. The incubating impulse thus developed and persisted 

 without eggs, nest, interchange with a mate, nest-building, or any sexual inter- 

 course with a mate. The cage of this pair was so placed that none of their own 

 species was visible. (Summarized from C 7/48.) 



LEUCOSARCIA PICATA. 



A pair of white-faced pigeons kept up their care of the young until it left the 

 nest at the age of 18 days. Two days later the egg of the succeeding cycle was 

 dropped, but it failed to develop. It is noted that "evidently the close care of the 

 young did not give the male a fair chance to fertilize the egg." (Sh 8/13.) Usually 

 the old birds begin to leave the nest near or at the end of 7 days, and cease covering 

 the young entirely by the twelfth day. In this case the unusual persistence of 

 the incubating impulse of one cycle disrupted the normal activities of the suc- 

 ceeding cycle. 



MOURNING-DOVE MALE AND WHITE-RING FEMALE. 



A male mourning-dove refused to mate properly when paired. He finally 

 courted and united with a female, but took no part in nest-building and incubation. 

 This behavior was repeated in several cycles. The female attempted incubation, 



1 The subsequent record shows, however, that the male made no repeated or prolonged attempt, possibly no 

 attempt at all, to continue sitting in or near the old nest. EDITOR. 



