126 WALLACE CRAIG 



3 .35. They try again, not successfully, I think. After fur- 

 ther preliminary reactions, the male makes a slight attempt 

 to perform the sexual act on the perch, but soon desists. 



3 :50. They make an attempt which is apparently successful. 



After this the male quickly learned to copulate with the 

 directness and efficiency which characterize experienced doves. 



He went through the process of incubating the eggs and 

 brooding the young. And in March, 1910, he fathered another 

 brood. But he was always liable to leave the eggs or the young 

 whenever a human being came into the room. He was, there- 

 fore, a very poor sitter and a poor brooder, and his young were 

 not well fed. Since I was hard pressed for room to keep my 

 birds, I felt I could not keep a bird which was worthless as a 

 parent: I gave Jack to the University of Maine, and he was 

 killed and mounted for the museum. 



Billy, No. 23. Hatched September 23, 1907. Father re- 

 moved October 1. Young removed from mother October 29, 

 his 37th day. 



In order to test whether the development of voice in the 

 young dove is at all due to exercise of the voice, I endeavored 

 to prevent this bird from kahing and cooing. I kept him in a 

 room by himself, with a brick apartment building between him 

 and my other doves, and with the room darkened, so far as 

 possible, at night. Kept so for months, he was far more silent 

 than other doves, but he did coo a little, prompted evidently 

 by internal stimuli. On January 6th I took him to a room in 

 the University of Chicago where he could hear one other Ring- 

 dove (Jack), and sometimes Common Pigeons; still he cooed 

 but little. The comparative lack of vocal exercise did not, in 

 any way that I could observe, retard or impair the development 

 of his voice. 



His display behavior appeared very suddenly; so far as I 

 observed, it appeared within three days, March 2, 3 and 4. 

 Billy gave himself to human companionship as heartily as Jack 

 had done, losing all fear of human beings, and showing all the 

 signs of excitement and joy in our presence. 



After his long period of isolation, Billy was introduced to 

 other birds on the same day and under the same circumstances 

 as Jack (see page 122). 



