218 WALLACE CRAIG 



This great transformation is determined by the entire social 

 situation which changes the dove from the status of the un- 

 mated (or it may be from some other stage in the brood cycle) 

 to the status of matehbod. No one factor determines it— not 

 the mechanical stimulation of the neck feathers, nor the act 

 of billing (which was one of Harper's suggestions), nor even 

 copulation. As to the preening of the neck feathers: I once 

 tried persistently preening the neck feathers of a dove which 

 refused to accept such action as from a mate : she showed no 

 laying attitude and laid no eggs. A dove which has been ab- 

 ruptly separated from her mate and given a strange male, 

 though that male preens her neck feathers and plays up to 

 her perfectly, may remain quite unstimulated. Conversely, the 

 females which were paired with their own sex, as above men- 

 tioned, preened one another very little as compared with males ; 

 yet they accepted each other as mates, and they laid eggs. 

 As to billing: These females mated with females again illus- 

 trate, for they billed but little and imperfectly, in some cases 

 not billing at all. And in the case of the birds induced to lay 

 by hand, there was of course complete absence of billing. As 

 to copulation : That this is not a necessary factor is proved by 

 the cases in which the female was induced to lay by preening 

 the feathers of the head and neck. Bartelmez (1912, p. 290) 

 mentions that a female may lay even when the male stimulat- 

 ing her is in another cage. Conversely, there are cases in which 

 a pair copulate regularly, yet the female does not lay. And in 

 some such cases the cause seems unquestionably to be that the 

 female is dissatisfied, as with her nest or other circumstances, 

 hence does not get into the laying attitude above described, 

 and consequently does not ovulate. I think that in some, though 

 not in all cases, one could prevent ovulation in a mated female 

 by persistently following her and turning her out of any corner 

 where she began to settle in the laying attitude. 



Data which will be given at length in other articles, show 

 that there is a difference in this respect between young doves 

 which have never mated and old doves which have been breed- 

 ers for years. The inexperienced are more ready to enter into 

 abnormal matings, — as, with their own sex, or with alien spe- 

 cies, or with the hand, — or to lay without a nest. They lay 

 eggs in conditions under which an old experienced dove would 



