56 A. H. Hamer 



understood. If I am asked why the would-be trespasser or inter- 

 loper should take heed of the warning song, colour or display; 

 my answer is, observation shews that the morale bestowed upon 

 the possessor by settled possession of territory appears among birds 

 tio be irresistible. The turkey-cock's display is palpably of a warn- 

 ing and threatening nature, and has no apparent influence on the 

 hens. There does not seem to be any difficulty in interpreting 

 the display of other birds in the same way. It is nothing out of 

 Nature's way if displays are also induced by excitement in the 

 presence of a mate. In my observation such displays are chiefly 

 induced in the excitement of first meeting a mate, a circumstance 

 which would naturally stimulate the territorial instinct. 



Real communication between the sexes is by quite different 

 methods, i.e. by soft sounds and endearments to which both 

 respond, and these are sympathetically recognised by ourselves 

 for what they are without any doubt. 



On our theory, then, the tails of the peacock and the argus 

 pheasant are their respective territorial banners; the brilliance of 

 the former has been developed by natural, not sexual, selection in 

 relation to its natural surroundings, and the *' eye pattern ** is one 

 excellently adapted for catching the eye of an intruder. 



Another difficulty of sexual selection is stated as follows: 

 "Sexual choice certainly cannot account for the remarkable or- 

 namental colours of the males of many fishes in the breeding 

 season, for in many cases the female may not even see the male 

 which fertilizes her already laid eggs. Eigenmann on the other 

 hand, notes the utter absence of such ornamentation among cave 

 fishes which live in the dark, and argues that where they do 

 appear, therefore, they must be due to visual selection." (Lull. 

 1917. p. 122). If these fishes are territorial as e.g. the 

 stickleback, our theory solves this difficulty. (C). 



We may now glance at some familiar examples of non-terri- 

 torial birds. Such are rock-doves, starlings, rooks, jackdaws* 

 our Cape weaver bird, and the sparrow. All except the last are 

 birds of strong flight, which is obviously necessary when a num- 

 ber radiate from one centre at nesting time. They have no vivid 

 warning colours. In each case the adoption of nesting sites in 



