416 The Philosophy of Birds 3 Nests. 



its nest generally of moss, a material always found where it 

 lives, and among which it probably obtains much of its insect 

 food; but it varies sometimes, using hay or feathers when 

 these are at hand. Books dig in pastures and ploughed fields 

 for grubs, and in doing so must continually encounter roots 

 and fibres. These are used to line its nest. What more natural ! 

 The crow, feeding on carrion, dead rabbits, and lambs, and 

 frequenting sheep-walks and warrens, chooses fur and wool to 

 line its nest. The lark frequents cultivated fields, and makes 

 its nest, on the ground, of grass lined with horsehair — mate- 

 rials the most easy to meet with, and the best adapted to its 

 needs. The kingfisher makes its nest of the bones of the fish 

 which it has eaten. Swallows use clay and mud from the 

 margins of the ponds and rivers over which they find their 

 insect food. The materials of birds' nests, like those used by 

 savage man for his house, are, then, those which come first to 

 hand; and it certainly requires no more special instinct to 

 select them in the one case than in the other. But, it will be 

 said, it is not so much the materials as the form and structure 

 of nests, that vary so much, and are so wonderfully adapted to 

 the wants and habits of each species ; how are these to be 

 accounted for except by instinct ? I reply, they may be in a 

 great measure explained by the general habits of the species, 

 the nature of the tools they have to work with, and the ma- 

 terials they can most easily obtain, with the very simplest 

 adaptations of means to an end quite within the mental capa- 

 cities of birds. The delicacy and perfection of the nest will 

 bear a direct relation to the size of the bird, its structure and 

 habits. That of the wren or the humming-bird is perhaps 

 not finer or more beautiful in proportion than that of the 

 blackbird, the magpie, or the crow. The wren, having a 

 slender beak, long legs, and great activity, is able with great 

 ease to form a well- woven nest of the finest materials, and 

 places it in thickets and hedgerows which it frequents in its 

 search for food. The titmouse, haunting fruit-trees and walls, 

 and searching in cracks and crannies for insects, is naturally 

 led to build in holes where it has shelter and security ; while 

 its great activity, and the perfection of its tools (bill and feet), 

 enable it easily to form a beautiful receptacle for its *eggs and 

 young. Pigeons, having heavy bodies, and weak Teet and 

 bills (imperfect tools for forming a delicate structure), build 

 rude, flat nests of sticks, laid across strong branches which 

 will bear their weight and that of their bulky young. They 

 can do no better. The Cajorimulgidce have the most imperfect 

 tools of all, feet that will not support them except on a flat 

 surface (for they cannot truly perch), and a bill excessively 

 broad, short, and weak, and almost hidden by feathers and 



