DISPLAY OF THE MALLARD IN RELATION TO PAIRING 83 



existent sequence of events, any struggle for breeding 

 territory which may take place in the Mallard must be 

 subsequent to pairing. 



To the question : does sexual selection exist in the 

 Mallard ? the appreciable facts seem to be sufficiently clear 

 and specific to allow of a definite reply. What appears 

 to the writer to be the leading points may be thus 

 summarised : 



Courtship is social, and a choice of mates so far 

 theoretically possible. 



While rivalry is apparent between individuals of the same 

 sex, its incidence is quite insufficient to prevent choice of 

 mates. 



The drake appears to respond equally to any duck, except 

 in so far as display by the latter is an excitant. He accepts 

 the attentions of any duck which may court him (during 

 which display is absent in both, with the exception of the 

 characteristic head-dipping of the duck), or at least discrimi- 

 nation is not apparent. True selection in his case is therefore 

 doubtful. Once mated, however, he repulses other ducks 

 who may approach him. 



The female likewise responds indifferently to display 

 before pairing ; but the series of events through which 

 pairing is attained is initiated by her courtship of an 

 individual drake ; and her choice is normally accepted. If 

 this be so, then sexual selection in the Mallard is an 

 actuality. 



The secondary query : by what influences is the female's 

 choice affected ? is much more problematical ; and here it 

 seems almost hopeless to look for definite evidence in the 

 field ; one can only approach the subject indirectly. I 

 suggest that the factors are to be sought in one or more of the 

 following three positions, which perhaps represent the most 

 generally held though usually intended as mutually exclusive 

 views of the numerous writers who have discussed the 

 general subject of sexual selection. 



1. The female's choice is "accidental," i.e., when in the 

 mood for pairing she accepts or selects any male who 

 may chance to be in near proximity. 



