CHANGING THE EGGS. 241 



building, much to the inconvenience and annoy- 

 ance of the original architect, who seemed at first 

 perfectly satisfied with her own fabrication. On 

 other occasions, when the same species of birds 

 were watched in another part of the same island, 

 they seemed to lay and hatch their own eggs with- 

 out any addition by the eggs of others. In the 

 windward district of Tobago, where this ordinary 

 method of incubation was seen, the savannahs 

 and swamps abound with underwood, shrubs, and 

 creepers; while in the leeward part, and especially 

 about Buccoo, scarcely a shrub or a bush is to be 

 seen. It might therefore be thought that probably 

 necessity had driven them to the cocoa-nut palms ; 

 this however does not account for the birds having 

 recourse to a common nest. 



It is a curious fact, that, during the process of 

 incubation, birds are in the habit of changing the 

 situation of their eggs in the nest. It appears that, 

 in some degree, this is necessary to the well-being 

 of the chick, although it is not precisely ascertained 

 what the object of the bird really is. It may be 

 to equalize the warmth, and to ensure the eggs 

 outside the others receiving the same degree of 

 heat as those in the centre of the nest. In arti- 



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