94 THE COMMON TREE-WARBLER. 



those of the Passerine birds are extremely 

 difficult to discover, and there are not wanting 

 zoologists who declare that these birds, comprising 

 the bulk of living species on the globe, are so 

 closely related, inter se, that they really constitute 

 but one great Family. 



The Common Tree- Warbler, therefore, having 

 plain-coloured young, scarcely differing from its 

 parents in tint, is a true Warbler, and we know 

 that after spending the winter in Africa, the bird 

 will renew its plumage in its southerti home, and 

 arrive in Europe resplendent in its freshly-donned 

 livery. None of our Thrushes undertake such a 

 journey. No Song-Thrush or Blackbird, Ring- 

 Ouzel or Fieldfare, crosses the Equator during 

 its winter wanderings, and the Mediterranean 

 countries are far enough travel for the above- 

 named Thrushes, if they would escape from the 

 snow which envelops their nesting-homes in the 

 cruel winter of the north, and forces them to fly 

 south in search of food. It is, perhaps, well for 

 them that they require no change of dress in 

 spring, for their bodies must suffer in the severe 

 struggle for existence during the winter, and 

 moulting must be an exhausting process, so that 



