158 CHILDHOOD OF ANIMALS 



to time the male and female relieve one another, and this is done 

 with a quaint ceremony of bowing, and with a careful scrutiny of 

 the egg before it is handed over. Large numbers of eggs are 

 destroyed by the weather, and so great is the desire of these birds 

 to brood that they will steal an egg for this purpose. Probably the 

 eggs are changed so often that family rearing has been replaced by 

 communism. In the sand-grouse and the bustards both parents 

 share in incubation, but in the great majority of the higher types 

 the female alone does the work. 



When the female only broods over the eggs, the male may take 

 no interest in the proceedings, or may remain as a guardian of the 

 nest and hen, or may assiduously feed her. As soon as the female 

 duck begins to sit, the drake flies off and does not reappear until 

 the young are nearly fledged. In gulls, most of the birds-of-prey, 

 swans, storks and rails the male keeps near the nest, and savagely 

 attacks any intruders. In Montagu's harrier and some other birds- 

 of-prey, the cock brings food to the hen, whilst it is almost the rule 

 amongst singing birds for the male to remain with the female and 

 assist in feeding her. The hornbill, which walls up the female in 

 the trunk of a tree during the breeding season, feeds her most 

 diligently, and indeed she would otherwise starve. 



All birds during incubation take a great deal of trouble with the 

 eggs, often turning and rearranging them, sometimes covering them 

 up when they leave them, and often bringing fresh material to add 

 to the nest. It is quite certain that sometimes because they have 

 been disturbed, possibly when some of the eggs have been taken, 

 and sometimes for no apparent reason, they get dissatisfied with 

 the nest, become suspicious and desert it. If a nest be disturbed 

 before its construction is completed, the birds generally leave 

 it and begin a new one somewhere near. In zoological gardens, 

 building birds are very capricious in this matter and will frequently 

 pull a nest to pieces and begin a new one, or desert the old one 

 entirely. When the eggs have been laid, what usually happens, 

 if a disturbance has taken place, is that the nest is deserted, and if 

 it is sufficiently early in the season, a new set of eggs is laid in the 

 new nest. Even when the young have been hatched, desertion is 

 the usual result when the parent has been disturbed or annoyed. 

 In similar cases amongst mammals, the mothers, even although 

 they are not naturally carnivorous, will kill and eat their own 

 young. 



Brood-care of another kind begins when the eggs hatch out, and 



