INSTINCT AND INTELLIGENCE IN BIRDS 97 



both birds instinctively secure the two requisites for successful incuba- 

 tion — even warmth and moisture — though in different ways. 



That the brush turkeys are descended from stock which possessed 

 the instinct of incubation is rendered probable from the fact that they 

 are gallinaceous birds, allied to the curassows, wild turkeys and grouse, 

 all of which build some kind of a nest and brood their young at the 

 present time. Further, the fact that the same mound is used con- 

 tinuously by the same birds, whether by more than one pair or not, and 

 is added to year after year, like the aerie of an eagle, and that in the 

 ocellated megapode, at least, the adults remain in the vicinity of their 

 mound and tend their young after leaving it, all suggest that this 

 mound must be regarded in the light of a nest, however modified from 

 the typical structure. From the stage seen in the ocellated magapode, 

 it is only a step or two to that found in others, where the parents never 

 see their 3'oung, for which they make ample provision, any more than 

 does a turtle or a mud-dauber wasp. 



More aberrant still, but in the same direction, is the behavior of the 

 moleo, in which as in the parasitic cuckoos, other changes have arisen, 

 which would render self -brooding difficult if not impracticable. Their 

 large eggs, six to eight in number, are said to be deposited at the 

 extraordinary interval of ten to twelve days, so that a period of three 

 months would elapse, between the laying of the first and last. Again, 

 unlike the fowls and birds generally, no turning of the eggs during 

 incubation is necessary. 



While nothing is certainly known concerning the history of these 

 peculiar instincts of the megapodcs, it is not unlikely that, as in 

 cuckoos and cowbirds, they have arisen through the modification of 

 earlier and more uniform instincts which the ancestors of all modern 

 birds seem to have possessed in common. 



VOL. LXXVII.- 



