'PROCREANT CRADLES' 113 



dead bough ; and the great spotted woodpecker, which is 

 about the size of a starling, sometimes chooses so small a 

 branch that great precision must be needed to keep the 

 tunnel straight in the wood, and prevent it bursting through 

 the thin surrounding wall. The opening of the lesser 

 spotted woodpecker's nest is a small neat orifice looking 

 as if a field-mouse had burrowed into a tree. 



Both the kingfisher and the sand-martin are familiar 

 examples of birds which excavate burrows for nesting in 

 banks of sand and loam ; but they perform the work with 

 implements of very different type. The bill of the king- 

 fisher is sharp, strong, and straight, resembling on a small 

 scale the beak of the heron, and is used for catching fish in 

 much the same way. It looks an effective pick, if an 

 indifferent shovel, and the kingfisher has probably no great 

 difficulty in boring its nesting chamber in a bank of loam or 

 marl by the riverside, which is the situation usually chosen. 

 The soft wide bill of the sand-martin, on the other hand, 

 appears a very weak tool for burrowing a hole two or three 

 feet long in sand which must always be compact and firm, 

 or the tunnel would cave in and imprison the worker. Yet 

 the sand-martin accomplishes it with great nicety and con- 

 siderable rapidity ; and it is surprising what firm and gritty 

 beds it often penetrates. Both birds as a rule bore a fresh 

 chamber every year ; the sand-martin uses an old nest-hole 

 rather more often than the kingfisher. Two more beaks of 

 burrowing birds of very different types are those of the puffin 

 and the burrow-duck or sheldrake. Both are fond of choos- 

 ing a burrow ready prepared by a rabbit, if they can find 

 one, as is also the habit of the stock-dove on sandy shores ; 

 but, unlike the stock-dove, they are able to burrow holes 

 for themselves. The broad bill of the sheldrake is very 

 different from the beaks of both the kingfisher and the 



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