654 MR. J, S. HUXLEY ON THE 



The number of Redshanks near the head of the estuary (where 

 alone they really congregated) was never very large. I should 

 put fifty as an outside limit, and from observations on this and 

 other species (e. g. Oyster-catchers), I believe that they are the 

 same individual birds day after day. Therefore, even allowing 

 that only a fraction of the coiirtships which reached the second 

 stage were consummated, yet the number of acts of pairing must 

 have been many times greater than the number of bii-ds ; pro- 

 bably, therefore, each bird pairs several times a day. 



It is thus likely, as Selous says, that the performance of the 

 courtship will vary very much in different circumstances ; there 

 may be satiety or eagerness in either sex, as well as timidity and 

 shjmess in the female, at difi'erent times. Selous addvices the 

 Pheasant to prove that the display of the male may be gradually 

 much abbreviated and scamped after the first few pairings. 



As regards 4, I have very meagre evidence. I can only say 

 that pairing had begun before the 8th of April, and was still 

 going on very vigorously when I left Wales on the 18th. All 

 the other questions I must leave for the present vmanswered. 



Selous' and my observations, however, are in themselves enough 

 to establish one important point, namely, that the actions of the 

 birds which lead iip to each single act of pairing are explicable 

 only on the Darwinian theory of Sexual Selection, or on some 

 modification of that theory. 



On the one liand, there is a very marked display by the male : the 

 fanning of the tail in the first two stages, the lifting and flutter- 

 ing of the wings, and the high-stepping with the legs in the 

 second stage, are all obviously calctilated to show off to the best 

 advantage certain conspicuous markings which are usually con- 

 cealed, while the rattling note of the second stage is to my mind 

 equally to be considered as an excitant. 



On the other hand, there is an equally marked p&wer of choice 

 shown by the female ; it is perfectly clear that if a female Red- 

 shank does not want to pair with any given male, he has no 

 possible means of forcing her to do so. He can only persuade 

 her, or rather attempt to persuade her (by means of his display), 

 and if she is very unfavourable to his suit, she can even prevent 

 him from doing this, by flying off directly he begins. 



Thus, though the male in this particular species has the 

 initiative, the. final decision must rest with the female. 



The chief postulate of Darwinian Sexual Selection therefore 

 holds good in the case of the Redshank : — The females have a 

 power of choice, and the cocks have to go through a display 

 before pairing. Moreover, tlie one certainly seems to stand in a 

 causal relation to the other. 



It is interesting to note, however, that although Sexual 

 Selection is at work, yet it has not produced any appreciable 

 difference between the sexes. This can be explained in one of 

 three ways. 



