Perhaps the most convincing evidence of all as to the 

 " instinctive " nature of flight, in nestling birds, is furnished by 

 the mound-birds, of the Malay Region and Eastern Australia. 



These extraordinary birds lay their eggs in heaps of decay- 

 ing vegetable-matter, or in the soil near hot springs ; and there 

 leave them to their fate. They lay very large eggs, it is to be 

 noticed, so large that the growing chick finds nourishment enough 

 within the egg to enable it to pass the ordinary nestling stage 

 while still within the shell. By the time it emerges it has both 

 grown and shed its first coat of nestling-down, and has developed 

 long wing-quills. Having burst its prison walls it wriggles its 

 way up through the loose earth, to the light of day, ready to 

 fight its way in the world unaided. Here, then, there can be no 

 question of " teaching " the young to fly. 



But some birds, at least, do, indeed, receive instruction when 

 on the wing. And in such cases, it will be noticed, their food 

 can only be captured by dexterous movements in full flight. For 

 a day or two, for example, young swallows simply practice flight, 

 to exercise and strengthen their wings. They are fed by their 

 parents when at rest. The next step comes when they are fed on 

 the wing, taking their food as they hover on trembling pinions 

 from their parents beak. In a little while the food is dropped as 

 the parent passes, and the youngsters are made to catch it as it 

 falls. From thence, onwards, they have to do their own hunting. 



123 



