PARENTAL CARE AND NEST-MAKING 297 



quill-feathers of the chicks are sometimes so long that they 

 can fly at birth, so everything works well. 



The mounds of the mound-birds, where part of the 

 warmth is due to fermenting vegetation, suggest the masses 

 of vegetation gathered by grebes and some rails. The birds 

 do not shirk the patience of brooding in their half-floating 

 nest, but they seem to trust partly to the heat of decom- 

 position. It is interesting to think of this inter-regnal co- 

 operation, an inter-twining of threads in the web of life, for 

 the Bacteria which are so often the minions of death are here 

 helping indirectly to foster young life. 



Nests in Holes,— From burying it seems natural to pass to 

 burrowing, and there are many birds that lay their eggs in 

 holes or tunnels, the excavation of which is more or less their 

 own work, though the holes of rabbits and the hke may also 

 be utilised. At the end of its long tunnel the sand-martin 

 makes a scanty bedding of roots and feathers collected from 

 far and near. The kingfisher makes in its hole a strange nest 

 of undigested fish bones. Rabbit-holes are sometimes 

 utilised by sheld-duck, even to a depth of ten feet or more, 

 but the bird also burrows of itself. The pufHn may utilise a 

 natural hole or it may burrow in loose soil. 



Just as some birds find a hole in the ground and utilise 

 or improve it, while others make the hole themselves, so it is 

 in regard to holes in trees. The woodpecker carves out a 

 hole in the decaying stem, while the nut-hatch usually finds 

 a hole and improves upon it by plastering up the entrance 

 so as to leave only a narrow doorway and by collecting the 

 scales of cones and fragments of bark to make a dry bed 

 within. A nut-hatch may have 10,000 tiny pieces of bark in 

 its nest, which represents a prodigious industry. 



The climax in the way of utilising holes in trees is seen 

 in the hornbills. A hole may be deepened if it is too 

 shallow or its floor may be raised if it is too deep. In some 

 cases the powdery dry earth obtained from the broken-down 

 hills of the termites is utilised for the bedding. The female, 

 who is weak and moulting at the time, enters the hole, and 

 the male narrows the doorway with resinous stuff and other 



