176 A HISTORY OF BIRDS 



the bird may almost be said to build a hole ! Turning now to the 

 " Coraciiform " birds we find that the majority breed in holes 

 in trees, or in burrows. The Kingfishers, Bee-eaters, Hoopoes, 

 Owls and the Woodpeckers and their allies serve as good 

 examples in this connection. The Bee-eaters especially deserve 

 mention, since these birds dig for themselves deep shafts sloping 

 obliquely from the surface and descending as much as ten feet, 

 at the bottom of which a slight nest of feathers is constructed. 

 Among the perching birds a considerable number breed in holes, 

 while the most striking burrower is the Sand-martin, whose 

 nesting colonies must be familiar even to those who are not 

 particularly interested in Ornithology. 



It would only be wearisome to describe in detail the nature 

 of the preparations made for the reception of the eggs. Suffice 

 it to say that in the majority of cases little or no nest is made, 

 the eggs, when laid in hollow trees, being deposited on the rotten 

 wood at the bottom of the hole ; but where a burrow is made, 

 in sandbanks, for example, a few leaves or grass are commonly 

 introduced. It would seem, however, that in some cases the 

 practice of nesting in a hole is of comparatively recent date, as 

 for instance, with the Golden-eye and Sheld-ducks, which still 

 make a nest of vegetable matter, lined with down plucked 

 by the female from her breast. * The Kingfishers again differ 

 among themselves. The fish-eating species build no nest, but 

 lay their eggs on the disgorged remains, the hard parts of the 

 fish and Crustacea on which they feed ; but those which feed 

 on insects or fruit appear to lay their eggs on a roughly con- 

 structed bed of leaves and straws (see also p. 192). 



Another and more important aspect of this subject is the 

 fact that not only do the burrowing species exhibit no sort of 

 special adaptation for the work of burrowing, but some even 

 appear to suffer therefrom : the beaks of the Bee-eaters, for 

 example, being quite worn down by their labours, a fact which 

 becomes the more remarkable when we reflect that the most 

 fragile of all these shaft-driving birds, the Sand-martins, appear 

 to suffer in no way by their digging operations, even though 

 they have the smallest of beaks. 



As a rule, probably, the work of excavation is carried on 

 by the aid of the feet, as in the case of the Sheld-duck and 

 Burrowing-owl (^Speotytd), but with the Kingfishers and the 



