Terriiorialism and " Sexual Selection " 59 



(D) Weavers often build in a tree away from water, near 

 grain fields from choice. (F.H.H.). 



(E) or after sunset as our Cape robin does. (F.H.H.). 



Addendum. 



Since writing the above I have had the pleasure of reading 

 Mr. Howard's "Territory in Bird Life" in which the idea of 

 territorialism is worked out in detail. 



There can be no doubt that territory plays a great part through- 

 out animate nature and territorialism must have a great influence 

 on the psychology of animals, including man. 



The point I wish to suggest is that colour in birds (also no 

 tloubt in fishes and other animals) as well as song is an adjunct 

 of territorialism and I may summarise as follows: — 



1 . Terntorialism may be assumed. 



2. Fights "a outrance" in nature occur seldom. The animal 

 feeling itself subject to superior moral or physical weight usually 

 retires and, besides this, Nature encourages the settlement of dis- 

 putes by bluff, and the assertion of morale orally and by attitudi- 

 nising. The closest tussles occur during the re-settlement of 

 territorials before a breeding season when neither combatant has 

 attained the morale bestowed by possession. 



Observation tells us that a bird rearing its young on a defended 

 territory is left more or less at peace, that such intruders of its own 

 species as appear are driven off easily by the morale of the " man 

 in possession." Common sense tells us that constant fighting would 

 interfere too much with the business in iife of the animal and 

 defeat the ends of territorialism. 



3. It has already been suggested that one of the uses of 

 song in birds is to warn off trespassers from the territory and I 

 now suggest that colour and plumes serve the same function. 

 The red on a robin's breast is admirably adapted to catch the 

 eye as he moves through the bush. The sugar bird flies over 

 his territory shaking the plumes of his tail. The ostrich parades 

 his boundaries waving the white plumes of his v/ings. 



4. Selection would act from the fact that by such degrees as 

 the territory is kept clear without actual fighting so would the 

 young be more efficiently raised. 



