2 THE STRUCTURE AND LIFE OF BIRDS CHAP. 



their grace and sprightliness. Not even the most 

 dazzling and ethereal of Humming-birds surpasses 

 the Wheatear in beauty. High spirits are another 

 sign of vitality in most if not in all birds. The Thrush 

 will sing by the hour together for pure jollity. With 

 our English birds this is the common way of giving 

 expression to hilarity. Some foreign species hold 

 most elaborate dances, and in all lands the fights 

 among the cock birds in spring are signs of exuber- 

 ant life. To find food and meet the actual needs 

 of the day seems easy enough, so that there is a 

 large surplus of energy to devote to pleasure or 

 rivalry. 



There is nothing in nature more wonderful than the 

 instincts of birds — for the present we must use this 

 much-debated word without explanation— nothing, 

 perhaps, that presents more interesting problems. 

 Take, for instance, the migratory instinct. The 

 Swallow travels to the south of Africa to spend the 

 winter and returns in spring to build her nest, often 

 in the very chimney where she reared her brood the 

 previous year. 



The nests are in many ways interesting, from their 

 beauty, from their wonderful variety — birds belonging 

 to the same family often building quite differently — and 

 from the fact that young birds have to build their first 

 nest without any instruction. Take again the extra- 

 ordinary instinct of the Cuckoo, and the still more 

 extraordinary instinct of her infant progeny. Then, 

 too, there is the death-feigning and wound-feigning 

 instinct. All these, however much they may be 

 studied, can never lose their interest 



