452 



ANIMAL LIFE-HISTORIES 



the addition of new material. As to my own observations, the 

 birds scrape together a new heap every year, as a rule, if not 

 always. They, however, begin this work four or five months 

 before laying the eggs, a provision which is very much to the 

 purpose. For mighty erections of this sort, the material for which 

 has to be carefully so gathered and chosen that the right tempera- 

 ture may develop in their interior, cannot be raised at a moment's 



bidding. Plausible 



as this appears to 

 ourselves, we must 

 admire the wonderful 



instinct prompting 

 the animals to make 

 such preparation for 

 eggs to be laid more 

 than three months 

 later." In New 

 Guinea and North- 

 east Australia the 

 place of the Scrub- 

 Turkey is taken by 

 another mound - 

 builder (Megapodius 

 tumulus, fig. 969), of 

 smaller size, the 

 mounds of which 

 may be as much as 

 ten feet high, with 

 a correspondingly 

 large diameter. The 

 nest is largely made of sand, and Semon describes one he 

 observed in Wednesday Island, which appeared to be constructed 

 of this material only. He suggests that the greater heat of the 

 sun in this warmer latitude renders the employment of vegetable 

 matter unnecessary. The chicks of all these non-incubating birds 

 emerge from the egg in a very perfect condition, and are soon 

 able to fly. 



The vast majority of flying birds incubate their eggs, the old 

 reptilian plan having been superseded. This is one of many 

 results which have followed from the successful solution of the 



Fig. 969. Mound of a Megapode (Megapodius tumulus}, much reduced, 

 as seen from above and in section 



