18 BEHAVIOR OF PIGEONS. 



THE "JUMPING OVER" PHENOMENON. 



This aspect of the mating behavior is nowhere mentioned in the manuscripts, 

 although Professor Whitman had commented on it in conversation with his students 

 and associates. The following account has been given by Dr. Riddle, who has 

 since studied and analyzed this bit of behavior in terms of degree of sexuality in 

 pigeons. 



If one follows closely the mating behavior of many pairs of presumably normal doves 

 it will be found that, in addition to the "mounting" by the male which is followed by a 

 consummation of the copulation, both male and female doves occasionally exhibit quite 

 definite motor activities of a similar or related sexual nature. The erotic male, for 

 example, will sometimes jump quickly over the back of the female. In many such cases 

 there is no attempt whatever to take the copulating position, but it seems to be the 

 reaction normal to a male in a state of submaximal sex-stimulation; perhaps the reaction 

 is associated with a weakly stimulated consort as well, for the latter usually thereafter 

 stoops more intently, or otherwise invites the promised union with more ardor than 

 before. The male, too, most commonly concludes his "jumping over" with a completed 

 copulation. 



It will be found, moreover, that an occasional female will sometimes mount the male. 

 Possibly it is a sexually unresponsive male, with a lagging response, that is thus humil- 

 iated; but so far as the writer has observed, it is also usually a female that is tubercular 

 that thus discounts the prerogatives of the male. In our experience, however, we have 

 not yet seen a female "jump over" the male. This latter reaction seems, among the pure 

 forms under consideration, to be a more distinctly masculine reaction than is that involved 

 in the mounting which precedes copulation. And this, we shall see in a moment, is true 

 once more among hybrid females when these are mated with each other. There it has 

 been shown that masculine females will "jump over" other females when the latter assume 

 strongly feminine attitudes. 



The study of the sex-behavior of hybrid females has been developed into a method of 

 arranging a group of sisters proceeding from a sex-controlled mating 1 in a quantitative 

 series of more and less "masculine" females. Concerning this situation we will, however, 

 make only a short statement here. It has been found that females from a mating so 

 arranged as to produce nearly all males from the stronger germs of the spring and early 

 summer, and nearly all females from the eggs of late summer and autumn, are not equally 

 feminine, as measured by their copulatory and "jumping-over" behavior. The first 

 females of the season, and from the relatively stronger germs generally, function more 

 often as males in copulating with their sisters hatched later in the season from weaker 

 germs. These same females, from stronger germs, also readily and often show the "jump- 

 ing-over" reaction, whilst this reaction has never been seen in many of the otherwise 

 most feminine females ; and it has been very infrequently seen in any of the more feminine 



ones. 



BILLING AND "FEEDING" BY THE MALE IN MATING BEHAVIOR. 



There is a widespread custom among pigeons to precede the sexual act by 

 what is known as billing. 2 In this act the male presents an open beak into which 

 the female inserts her own. This process is of longer or shorter duration, and 

 varies greatly for the different species. During this process there is evidence for 

 a regurgitation, by the male, of a small amount of food into the beak of the female, 



1 These matings are described in Volume II. 



2 This process is well known in the various varieties of domestic pigeons. The phenomenon is also referred to 

 in the materials cited in Chapter X. 



