76 BRITISH BIRDS. 



had a Nightingale, which I reared by hand ; it would eat meat out of my fingers, 

 and was quite tame. When the time of departure arrived it became restless, 

 beat about the cage, and knocked its tail to pieces." Now first the bird, 

 which had known no parents and looked to the old bird-catcher for both, 

 discovered that it was a captive, and, feeling the migratory impulse, endea- 

 voured to respond to Nature's lead, which wires and prison bars prevented. 

 A human being might have thought, though the poor bird could not, of the 

 beautiful lines of Lovelace — 



" Stone walls do not a prison make, 

 Nor iron bars a cage ; 

 Hearts innocent and quiet take 

 These for a hermitage." 



This bird was not moved by instinct ; it suffered from positive corporeal 

 pain, i. e. migratory impulse. 



A vague sense of danger sometimes causes movement. Want of light has 

 been said (by a Swedish author, I think) to send birds south. Many come to 

 this country to breed ; others leave it for that purpose : Woodcocks do so,yet 

 not all. The reason why some go and some stay I take to be partly persecution 

 and partly want of food. Also northern visitors stop for a time, while Biitish- 

 born birds move south. When Nature wishes to cause any action, she uses 

 pain and pleasure as agents, which always, as a rule, produce the required 

 result. 



The migratory impulse must be very strong. It is blindly followed by 

 the Quail, which will, if possible, fly through a house or over a mountain 

 rather than turn from its course. " In this respect it resembles the Norwegian 

 Lemming, whose onward journey is stopped neither by lakes nor hills, and 

 some species of ants, whose movements are equally undeviating " (Mr. Gould's 

 ' Introduction to the Birds of Great Britain,' 8vo edit. p. 8). 



All animals have an instinct of self-preservation ; but in the above 

 instance the migratory impulse overcomes it, and is the stronger of the two. 

 Nevertheless the single individual would not run into dano;er of its own accord; 



