SOME COMMON BRITISH BIRDS 81 



In the tree-sparrow, on the other hand, the sexes are alike 

 in colour, and therefore indistinguishable externally. From the 

 house-sparrow this species may be readily distinguished by its 

 slightly smaller size, and in having the whole of the crown russet 

 colour, two white wing-bars, and a black patch on the sides of 

 the neck. 



Why, in species so closely related, there should be such a marked 

 dissimilarity in the coloration of the sexes is at present a mystery. 

 And here may be mentioned a " law " as to the coloration of the 

 sexes which is of peculiar interest. As a rule, the sexes are dis- 

 similar, and the male is the brighter. In such cases the young 

 in their first plumage resemble the female. Where the sexes are 

 alike in colour the young either have a livery of their own, which 

 is always dull as in the case of the starling or they resemble 

 their parents, lacking perhaps something of their brilliance, as 

 in young kingfishers. 



In comparing the house- with the tree-sparrow attention 

 should be drawn to the marked difference of disposition of the 

 two species. For the house-sparrow may almost be called a 

 parasite, never leaving the neighbourhood of human habitations. 

 Wherever man has established himself, there, throughout the old 

 world, will the house-sparrow, or some sub-specific race thereof, 

 be found. Pugnacious in character, it drives away other and 

 more desirable species ; and by its numbers makes itself a nuis- 

 ance, since it has developed an insatiable appetite for corn, levy- 

 ing a heavy toll wherever this is grown ; while it makes no ade- 

 quate return in the destruction of noxious insects. Insect food, 

 indeed, is a diet they never partake of, though for a week or two 

 they select this for the nourishment of their young. 



The tree-sparrow, on the other hand, seems to shun the 

 society of man, frequenting rather the pollard willows along 

 the edges of the streams. But it is extremely local in its distribu- 

 tion, and is nowhere numerous. As a matter of fact, it may 

 well be that the retiring habits of the tree-sparrow are rather 

 the consequence of necessity, imposed upon it by the tyrannical 

 house-sparrow. At any rate in some Eastern countries, and 

 especially in China, the tree-sparrow replaces the house-sparrow, 

 and displays the same preference for human habitations. 



VOL. I. 6 



