78 BEHAVIOR OF PIGEONS. 



being forced from the nest and driven to the perch. Apparently the only possible 

 stimulus of the incubating impulse in this case must be found in the previous activ- 

 ities of courting and mating. The author makes no specific reference to the male. 

 In all probability the incubating impulse was not awakened in the male. 



The previous cycle was broken up by driving the female from the nest at night. 

 The new cycle began on the 6th; on this date she first took the perch at night of 

 her own accord and sexual unions first began to occur freely. The later records 

 are given in the following excerpts: 



Feb. 7. -The female takes her place on the perch to-night for the second time 

 without help. 



Feb. 8. L 2 went on the perch to-night, of her own accord, for the third time. 



Feb. 9. L 2 is again on the perch. The male tried to induce her to build a nest 

 to-day, but she did not stop long. 



Feb. 24. After sitting on the perch at night for a week or so (since Feb. 6), the 

 female again returned, now some days since, to sitting at night without laying. I have 

 driven her off every night, and have sometimes had to cover the nest to keep her off. Still 

 she has kept on trying to sit up to the present. On Feb. 25 she abandoned sitting at night 

 and of her own accord took the perch. The same occurred on the nights of the 26th and 

 27th. On Feb. 27 she spent some time making a new nest, and on the 28th she spent nearly 

 the whole forenoon receiving straws, the male working almost continuously. (R19.) 



THIRD CYCLE. 



In this cycle the male's incubation record was normal for 3 days. He then 

 began to deviate from normal conduct by making sexual advances to his mate. 

 This sexual impulse arose gradually and increased in strength. Its origin can not 

 be due to any external objective conditions, and the author attributes it to much 

 rich food. The sexual impulse does not at first entirely destroy or terminate his 

 impulse toward incubation; it merely interferes with the normal expression of the 

 latter. Incubation was probably not terminated entirely until the female began 

 to respond and unions resulted. The female continued the incubation activities 

 for 9 days in spite of the advances of her mate, his defective participation in incu- 

 bation, the substitution of a set of old eggs, and the breaking of one egg. The 

 removal of the second egg was apparently the final stimulus necessary to break 

 up the cycle. This cycle is described with much detail in a diary record. It began 

 on February 25, and after a short mating period the first egg was laid on March 1, 

 between 4 and 6 p. m. The second egg was delivered at 9 h 48 m a. m. on March 3. 

 The record was entirely normal for both birds until 5 p. m. March 4. The devia- 

 tions of the male and the termination of the cycle are described in the following 

 excerpts : 



Mar. 4. At 5 h 02 m p. m. the male tried to crowd into the nest. He fondled the head 

 of the female and appeared to take great delight in his paternal caresses. He pressed so 

 hard to get possession of the nest that I felt anxious for the eggs. He continued to sit 

 beside the female until long after dark, until 8 h 45 m p. m., and then took aplace on the edge 

 of the nest-box, close by the female and with his head turned towards her. 



Mar. 5. At 6 h 27 m a. m. the female came off the nest, and the male flew up to the 

 nest and back to the floor of the pen four times. He seemed undetermined what to do. 



