44 



BRITISH BIRDS 



is general ; and as no one has said that they hibernate, like swal- 

 lows and cuckoos, they must go to other lands beyond the sea. 

 That they make a greater mystery of their departure than other 

 migrants is all that can be said (at present) about the matter. In 

 spring, in like manner, we do not see their coming : they are again in 

 the shrubbery, from which they have probably never been missed, 

 being such shy, skulking birds. 



Nesting begins in March, the site selected being the centre of a 

 hedge, or a thick holly or other evergreen bush, or a mass of ivy 



FIG. 19. THROSTLE'S NEST. 



against a wall or tree. The nest is built of dry grass, small twigs, 

 and moss, and plastered inside with mud, or clay, or cow-dung, and 

 lined with rotten wood. This is a strange material for a nest to be 

 lined with, and is not used by any other bird ; the fragments of 

 rotten wood are w r etted when used, and, being pressed smoothly 

 down, form a cork-like lining, very hard when dry. Four or five 

 eggs are laid, pale greenish blue in ground-colour, thickly marked 

 with small deep brown spots, almost black. Two, and sometimes 

 three, broods are reared in the season. 



