AUTUMN BIRD LIFE 243 



tion rations, and the depressing atmospheric con- 

 ditions of the North had given place to a warmer 

 climate, with comparative plenty ; and the former 

 was the cause of the silence, the latter of the song. 



The warblers cease singing during the remainder 

 of their stay with us, after the nesting ; because they 

 are moulting for their long flight, and, consequently, 

 in indifferent health. But, when they reach the far 

 side of the Mediterranean, where another summer 

 awaits them, and a continued supply of their 

 favourite food, they, probably, resume their song ; 

 although there is no reason to believe that they 

 mate, or nest afresh. 



The chimney swallows warble on delightfully 

 till they leave in October. The reason for the ex- 

 ception seems to be that, unlike the other migrants, 

 they do not moult in the autumn; while the air 

 is mild, food plentiful, and all the other conditions 

 of song are present. Their mute season is in the 

 spring, which is their time for changing feather, 

 against the northern passage ; when all the warblers 

 are vocal. 



I know only two birds, in this latitude, which 

 seem able, amid adverse conditions, to maintain 

 sufficient health and spirit for winter song. 



The robin is the autumn bird par excellence. 



