112 NATURE-STUDY 



nests. The coarsest material is placed on the foundation 

 and at the outside. Many birds put a lining of horse-hair or 

 feathers on the inside of the nest. The eider duck's nest is 

 chiefly of feathers plucked from the breast of the mother, and, 

 when the nest is left, the eggs are carefully covered with 

 feathers. 



The various materials are carefully woven together, the 

 bird using its bill for the purpose. Even the mud is carried 

 in the bill. The general form of the nest is moulded by the 

 bird's pressing the material into shape with its body. Watch 

 a robin building a nest, and you will see the bird frequently 

 squatting down and turning about in it to give the materials 

 the desired shape. 



Birds often display considerable ingenuity and discretion 

 in the choice of a location for the nest. Some seabirds, on 

 inaccessible islands and cliffs, do not need much of a 

 nest for the protection of the eggs and young; but where 

 enemies are liable to intrude, the nest must be made incon- 

 spicuous or placed in a safe location. The red-winged black- 

 birds, marsh wrens, and bobolinks find safety by building in 

 the swamps and marshes. The first makes a large, loose nest of 

 marsh grasses, woven together and fastened to reeds or cattails. 



A number of birds live in hollows in trees or stumps, as 

 the wren, flycatchers, nuthatches, brown creepers, chicka- 

 dees, and bluebirds. Woodpeckers dig out their own hol- 

 lows in dead trees by means of their stout chisel beaks. 

 Their nest is lined only with wood chips. Owls are often 

 found in large hollows in decayed trees. 



The crevices and ledges of cliffs are selected by many birds, 

 especially on the seacoast by sea-fowl. Phoebes and cliff 

 swallows also lodge in such places. 



