138 BIRDS' NESTS 



to an immense amount of modification, and presents 

 an almost endless diversity, not only in the materials 

 of which it is composed, but in the situation in which 

 it is placed. We shall find that the type, although 

 always "open," presents every possible amount of 

 variation in form from that of a shallow saucer to 

 a deep cup, and from the size of a walnut to a 

 gigantic structure containing a cartload or more of 

 material, the latter varying from the softest downs 

 and mosses to sticks and branches several inches in 

 circumference. Its position is none the less variable, 

 for we shall find it in almost every conceivable situa- 

 tion, in trees and bushes, amongst grasses, aquatic 

 vegetation, and herbage of all kinds, as well as on 

 rocks and the ground, or even in water, upon the 

 surface of which it in some cases safely floats. 



In the first place, it may be as well to deal with 

 a few of those simpler forms of open nests made 

 by species belonging to groups already noticed, such 

 as the Anseriformes, Galliformes, and Lariformes, in 

 which the predominant type of procreant cradle is 

 a crude one. The Grey-lag Goose (Anser cinereus), for 

 instance, generally constructs a huge nest — three feet 

 in diameter at the base, and upwards of a foot in 

 height — of branches and twigs of heather, dead rushes 

 and reeds, dry grass, bracken leaves, and turf, and 

 lined with moss, to which is added, as incubation 

 advances, a thick bed of down and feathers. This 

 open nest is built upon the ground amongst tall 



