SEXUAL SELECTION IN BIRDS. 203 



another, each couple going side by side, then turning, as 

 Partridges do, the two that were pursued now pursuing in their 

 turn. This may be enmity, but it has more the appearance of 

 social excitement — whichever of the two it is, it looks most 

 bizarre. As I say, as yet there has been no unmistakable sign 

 of hostility, but now two of the birds, belonging to opposite pairs, 

 fly twice or thrice at each other, in a way which should settle 

 the question. Yet this, too, may be social excitement, or the one 

 thing may pass into the other. Say, however, that it was 

 fighting — as, whatever its origin, it was — and it follows that 

 these birds fight in couples, which is surely an interesting 

 characteristic. True, the females may not actually come to 

 blows — the sexes unfortunately are indistinguishable — but, at 

 any rate, they help in the leading-up part. I am sure that both 

 sexes were represented in the above episode. This, however, is 

 an important point, for if the female bird is able to drive off any 

 male she may not care about, or to help a successful rival to do 

 so, we can the better see how her choice — assuming her to have 

 one — might be made effective. I will therefore quote from my 

 notes of last year, in which the co-operation of the female with 

 the male — her own husband — in a case somewhat similar, is 

 demonstrated. 



July 5th, 1905. — Whilst I watch I have a good illustration of 

 how a pair of married Oystercatchers may act, together, against 

 any third party. Twice has such a de trop individual, by associ- 

 ating itself with the male, got close to the nest, on which the 

 female, leaving it, walks up to them, and, placing herself beside 

 her mate, they both, as it were, pipe a warning, whilst advancing 

 upon the intruder. This, if he does not go, develops into an 

 attack. In the first case, here, it did, when he soon flew off. In 

 the second this happened before an actual attack was necessary. 

 Having watched this pair of birds for many days, I could feel 

 assured that the one then, and almost always, on the nest was 

 the female. If, then, it be asked, " How, in bird life, can the 

 female get rid of a distasteful suitor, who is yet stronger than a 

 more attractive rival?" we can answer, "By joining with this 

 rival against him," for the facts above noted make this, at least, 

 possible. 



April 11th, 1906. — Two Redshanks, after pairing, run, in an 



