INSTINCT OF THK CUCKOO. 311 



The extraordinary strength of the newly-hatched birds is ac- 

 counted for by the size of the egg, since in so large a volume 

 it is reasonable to suppose that the young ones would be much 

 more developed than is usually the case. 



Even where architectural skill is totally wanting, and no nests 

 are built or no leaf-mounds raised, the birds evince an admi- 

 rable care for the welfare of their future progeny. 



The sea-lark contents herself with laying her four eggs in a 

 small cavity on the ground, but places them with the small 

 ends touching each other as a centre, so as to occupy the least 

 possible space, and thus to be more easily hatched. No mathe- 

 matician could have solved the problem in a more perfect 

 manner ; and is not this instinct, after all, as wonderful as that 

 which prompts other birds to construct the most complicated 

 dwellings ? Even the auk, who lays her single egg upon the 

 bare edge of lofty rocks hanging over the sea, invariably selects 

 the safest spot against wind and weather ; and though numbers 

 of birds may be breeding on the same ledge, yet no confusion 

 ever takes place, for every mother, guided by an unerring in- 

 stinct, knows her own egg, and is able to find it among 

 hundreds. 



The parental instinct of birds might be supposed to have 

 reached its lowest ebb in the cuckoo, who never hatching her 

 own eggs, deposits them in the nests of other and smaller birds, 

 such as the hedge-sparrow, the titlark, or the water-wagtail ; 

 but it would be doing the parasitical intruder injustice to 

 attribute this shifting of her own burden upon the shoulders of 

 another to a peculiar coldness of disposition, or to a culpable 

 neglect of duty ; for as the caterpillars on which the large bird 

 feeds do not afford sufficient nourishment for a rapid evolution 

 of germs, the cuckoo lays but one egg every eight days, from 

 the beginning of June to the middle of July, and it surely 

 would be a grievous task were she obliged to incubate during 

 the best part of the summer. But a most admirable instinct 

 has taught her to seek a substitute for a duty she is unable to 

 perform herself; and it is not the least wonder of this strange 

 history, that the eggs of the cuckoo are of an unexampled 

 smallness, so as to differ but little in size and appearance from 

 those of the skylark and titlark, though the disparity of the 

 bulk of the birds is very great. Thus we see that though the 



