158 BIRD BEHAVIOUR 



in the egg appears to be able to proceed in some 

 cases without any extraneous heat, such as is cer- 

 tainly generated in the Brush-Turkey's mound by 

 the decaying vegetable matter. More than a 

 dozen years ago, some eggs of the Nicobar Megapode 

 were taken from a mound in the islands and put 

 on board the Government ship Elphinstone. Here 

 they were allowed to lie about on deck in a bucket, 

 and when the ship got up to the British settlement 

 in the Andamans they were put away in a cup- 

 board ; nevertheless some chicks at all events 

 hatched out and were reared, and I saw these at the 

 Calcutta Zoo, where they were sent when full 

 grown. It would appear, however, that the tem- 

 perature in these Megapodes' mounds is not high, 

 the part where the eggs are buried being if anything 

 cool to the touch. 



The Mound-birds are a group with a long incu- 

 bation-period, the Brush-Turkey, a bird of the 

 common Fowl's size, taking six weeks ; the incuba- 

 tion-period of birds being a group-character or 

 minor habit, differing in length according to the 

 family to which the bird belongs, but, in the case 

 of birds of the same family, being generally in 

 proportion to the size of the species, large birds 

 generally taking a longer time than small ones. 



Thus, among our familiar tame birds, the Fowl, 

 as most people know, takes three weeks, the Turkey 

 and Peacock a month ; the common Duck takes a 

 month, the large Muscovy Duck five weeks, the 

 Goose four, the Swan six. Both the Duck and 



