i6o THE BIOLOGY OF THE SEASONS 



lays its eggs on the shingle, where they are so like rounded 

 pebbles that they are most effectively lost to ordinary 

 vision; and Professor Newton points out the interesting 

 fact that even when the bird lays its eggs on grassy 

 uplands, it still " paves the nest hollow with small stones." 



One of the most charming of ground nests is that of the 

 eider-duck, where a thick quilt of down is accumulated 

 that can be drawn over the eggs when the mother-bird 

 goes down to the sea for food. 



In not a few birds the only care is to bury the eggs a 

 way of securing their safety that recalls suggestively the 

 habits of some reptiles, such as crocodiles, which are 

 historically antecedent to birds. The New Zealand kiwi 

 puts its single big egg in a hollow among the rhizomes of 

 the tree-fern ; the female ostrich lays her eggs in a hole 

 which the cock scrapes in the sand, and both birds share in 

 brooding. Some Mound-birds or Megapods bury their eggs 

 in the sand and leave them, while others heap a huge hot- 

 bed of dead leaves over the spot . Dr. Alfred Russel Wallace 

 has told us that many mother Megapods in Celebes come 

 from a distance of 10 to 15 miles to the vicinity of certain 

 warm springs, where they like to lay their eggs. A huge 

 mound is built, 5 to 6 yards high, 30 feet round, and many 

 mothers co-operate. After they have laid their eggs on 

 the mound they depart, leaving the eggs to hatch all un- 

 tended. If they stayed they would find difficulty in getting 

 enough to eat, for they feed upon fallen fruit ; and there is 

 no need for them to stay, since the young birds have a quite 

 unique adaptation the quill feathers are so long to start 

 with that the chicks can fly away from the mound on the 

 very day of their birth. 



Grebes and some rails collect pieces of water-plants and 

 " form of them a rude half-floating mass, which is piled on 

 some growing water-weed"; and while they do not shirk 



