8o THE SCOTTISH NATURALIST 



perhaps significant that action No. 5 which is the most 

 frequent and developed of those shown by the duck is 

 invariably assumed by the drake immediately after coition. 

 The other display-actions occasionally exhibited by the 

 female include Nos. 1 and 6. 



It is worthy of notice that the autumn development of 

 " nuptial " plumage in the Mallard coincides with the incep- 

 tion of display and related behavour ; that is to say, the 

 correlation of seasonal ornamental plumage with display, 

 characteristic of birds in general, is not interfered with by the 

 seasonal abnormality in the acquisition of the said plumage 

 in the present species. True display is localised, being 

 practically confined to water ; it is entirely a social 

 phenomenon, and (with the exception of No. 5) it is absent, 

 so far as I have seen, in truly paired birds. Thus in the 

 Mallard, contrary to what obtains in many species, there is a 

 difference in kind between pre-pairing and nuptial " play." 1 



The general features of display are as follows : A 

 number of birds of both sexes swim restlessly to and fro 

 within a circumscribed area, the drakes for the most part in 

 attitude No. 1, from which they proceed from time to time to 

 No. 6, and, perhaps less frequently, No. 2. Further develop- 

 ment is largely, though not exclusively, dependent upon the 

 behavour of the ducks, tending to abeyance in face of in- 

 difference or lack of display in the latter sex. On any sign of 

 excitation in the female, however, such as display - action 

 No. 5, the drakes are instantly stimulated to respond by 

 actions 2, 3, 4, and 5, and more especially the two last of 

 these. Despite the extreme sensitiveness of the inter- 

 sexual behaviour response, these displays, in either sex, have 



1 It might be of interest to discover how far display is maintained in 

 artificial breeds of the Mallard. It remains complete, or almost so, in 

 the Call-duck, which is chiefly monogamous. As to the polygamous 

 farmyard varieties, I have noticed it in the Indian Runner, although 

 it is, I think, of infrequent occurrence. I do not recollect ever seeing it 

 in the Aylesbury. On the other hand, the side-dipping motion of the 

 head in the female, which in the wild bird is common both to courtship 

 proper and to the nuptial period, remains in full force in the domestic 

 races, as do also the actions immediately related to coition, such as the 

 head-bowing of both sexes. 



