NATURAL SELECTION 73 



Between the crises there is peace and happiness. There is 

 often, it is true, an unceasing alertness well suited to an atmos- 

 phere of danger. But the alertness seems due to an unfailing 

 protective instinct, not to nervous anxiety. A curlew has no 

 nerves. Moreover there is no painful memory of past perils 

 till something arises to recall them. Of this we may feel 

 reasonably sure, since animals express the emotion of fear in 

 a way that admits of no misinterpretation. 



The commonest crisis of all is that which comes in early 

 youth. When in the nest, the young sparrow lives like a fight- 

 ing cock, caterpillars are brought to him by the score. But 

 when he emerges he must very soon begin to fend for himself, 

 and if he fails in energy or nous he will soon be no more. But 

 should he succeed in surviving this time of trial, he may live for 

 some years vigorous and joyous. A hard winter may mean 

 another crisis for him. If he survives this, being good at finding 

 food where others would starve, or getting more than his fair 

 share by hard fighting, it means that in ordinary weather he will 

 have a surplus of energy. 



The young swallow has hundreds, or perhaps thousands, of 

 flies and gnats brought him daily while he is still in the nest. 

 When he is first trying his wings his parents will come along- 

 side and in mid-air put flies into his mouth. But this soon comes 

 to an end. He must forage for himself or starve. This is his 

 first great trial, but soon another is upon him. He must either 

 find his way to Africa and spend the winter there or die in 

 England. Supposing that he reaches his destination, the winter 

 time in the south has probably no very great danger for him. 

 But in the spring an uncontrollable instinct comes over him. 

 He must fly northward and face storms and all the dangers of 

 travelling. Here there is another crisis. If he survive this, 

 it is probable that the path of life will be smoother for him. 

 Experience has robbed migration to a great extent of its dangers. 

 Food is plentiful both in his summer and winter homes, and 

 there are not in the present day many hawks, in his northern 

 home at any rate, that can catch him. 



For our birds at home a hard winter is a trying time, not so 



