202 The Irish Naturalist. [August. 



glossy. No. 3 is the smallest. Its " frill" is least developed, 

 and the feathers show almost no sigii of g^loss. The im- 

 portance of these facts will be discussed presently. 



The ground is now somewhat cleared, so that an attempt 

 may be made to answer two much vexed and contended 

 questions, i. For what function is the " ruff" or " frill "" 

 developed ? 2. Why are its feathers of such rich and varied 

 colours in different examples ? The first question has been 

 fullj^ dealt with, and in connection with it many explanations 

 have been offered. When Darwin first enunciated in a definite 

 way his theory of Sexual Selection^ he took the Ruff among 

 other birds as a tj'pical example to illustrate the " I^aw of 

 Battle." The males (poh'gamous in nature like many 

 gallinaceous birds) fight for the possession of the females. 

 Space does not permit me to describe the combat.^ Sufiice 

 it to say that the neck feathers are erected resembling a 

 shield, which is supposed to protect the more tender parts. 

 The shield-like function of the "ruff" feathers has been 

 pointed out by Montagu, subsequently mentioned b}^ Darwin, 

 and advocated by others. But that this is not the main 

 function of these feathers is shown by the following facts : — 



Firstly. — The nature of the " frill" feathers. They are soft^ 

 wav>% and offer but little protection. 



Secondly. — Their position. Assuming even that the}' protect 

 tender partSy some of the most vital parts are exposed to 

 danger, for the shield is absent over the head and face and 

 wattles, regions which in other fighting birds are frequently 

 injured. 



Thirdly. — According to Montagu every feather, as well as 

 those of the "frill," is more or less distended. Hence it is 

 likely that the cause of this general erection is one simply 

 of anger or excitement.^ 



Fo2irthly. — Ruffs fight at other times of the year. Why are 

 they not always protected by a neck shield ? 



1 "Descent of Man," p. 360. 



- Macgillivray, " Hist. Brit. Birds," vol. iv., 1852. Also Yarrell "British 

 Birds," vol. iii., p. 427 to 434 ; and other standard manuals. 



3 J. T. Cunningham points out that erection or display of feathers is 

 often invariably associated with excessive development. (Sexual Dimor- 

 phism, 1900, pp 108-154-155.) 



