1903 Moffat. — The Spring Rivalry of Birds. 163 



on a part of the Missel-thrush's property. When such is the 

 animosit}' shown by birds in spring against individuals who 

 are not of their own species at all, it is not hard to understand 

 how the rivalry of those which are of the same species 

 gradually results in a certain parcelling out of the country, 

 and substitutes arithmetical for geometrical progression as the 

 normal avian birth-rate. 



There remains a collateral point on which I think I should 

 touch. The advocates of what is called Sexual Selection will 

 probably say, in opposition to what I have tried to advance, 

 that it offers no explanation of the beautifully ornamental 

 plumage in which so many male birds are arrayed, or of the 

 sweet flow of song with which, in a still larger number of cases 

 they delight our ears in spring. If the great difficulty of a 

 cock-bird in spring is to gel a plot of ground, andhis prospects 

 of matrimony are dependent on that, why, it will be demanded, 

 should he need to have a fine voice or fine feathers ? If his 

 difficulty is to make himself pleasing to somebody else, the 

 explanation is simple. The song and bright plumage of a 

 cock-bird are, on this theory, the charms by which he estab- 

 lishes his place in the heart of her to whom he pays court. 

 But how do they help him to win a plot of ground ? 



Well, as regards song, it has long been a subject of contro- 

 versy whether or not it is addressed to the female at all. So 

 far as outward indications go, male birds appear to address 

 their songs primarily to one another. We hear them answer- 

 ing one another from field to field, sometimes from hill to hill, 

 and the song partakes so strongly of the nature of a challenge 

 that a great many birds actually sing while they are fighting. 

 The Robin almost habitually does so ; and the Wood-pigeon's 

 peaceful " coo " — as it sounds to our ears — is often uttered in 

 the midst of a deadly combat. I have also heard Thrushes 

 singing their loudest in the thick of a fray ; and Mr. Charles 

 Witchell, the author of the Evolution of Bird-Song has 

 noticed the same habit in the Tree-pipit, Chiffi^haff, Willow- 

 warbler, and Golden-crested Wren. But it is still more usual 

 for song to provoke to combat, and here I think the general 

 rule is accurately stated by the ornithologist Couch, who 

 observes that '' in a wild state birds of the same soecies will 

 not sing near each other, and if the approach be too close, and 



