THE NATURAL HISTORY OF NESTS 



bedding is added ; or to the magpie's, where the 

 erection is fenced round with thorns. 



An offshoot in a different direction is represented 

 by birds that make burrows or tunnels or excava- 

 tions of some sort, getting as far as possible into 

 private life. In its safe retreat the sand-martin 

 makes a scant bed of roots and feathers collected 

 from far and near. The kingfisher makes a stranger 

 one of undigested fish-bones . Sheldrakes and puffins 

 often utilize rabbit-holes. The woodpeckers carve 

 out holes in decaying trees ; the nuthatch plasters 

 up part of the doorway. In the case of the horn- 

 bills, the female is weakly and moulting at the 

 breeding-time, and the male shuts her into a hole in 

 a tree-stem. The floor may have to be deepened, 

 or it may have to be raised with dry earth from the 

 termitaries. The doorway is built up, too, so that 

 intruders are readily kept out, while the hole is 

 large enough to let the male bird's bill in. It is 

 on him that the labour devolves of -finding food for 

 his mate, and afterwards for his family as well. He 

 is often worn thin with his other-regarding exer- 

 tions, while the female bird becomes fat. Some- 

 times, the story runs, the male bird dies without 

 having the reward of even seeing his children. 



Cases, like that of the hornbill, where there is 

 some building as an accessory to the nest, point the 

 way to definitely built nests, such as those of the 

 swallow and the house-martin. The swallow's is 

 the more primitive of the two it is made of mud 

 strengthened with pieces of straw ; it is like " half 

 a deep dish," open at the top ; it is built against 



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