BIRDS' NESTS 313 



part, is surrounded by a thick rampart, a sort of 

 fortified enclosure composed of thorny twigs se- 

 curely intertwined. One would take the whole thing 

 for a shapeless mass of brushwood. Through this 

 rampart, on the side that is most strongly defended, 

 an opening is left of just sufficient size to admit of 

 the mother's entrance and exit. It is the only door 

 to the aerial fortress. 



"Let us turn now to a bird that builds upon piling. 

 It is a warbler of large size, called the great sedge- 

 warbler or river-thrush. It selects a cluster of four 

 or five reeds that project above the surface of a 

 pond, with their stalks rooted in the mud under the 

 water and growing near together. These slender 

 piles, the tops of which the bird brings into such 

 proximity as may be desired and fastens with con- 

 necting strands, are made to bear an interlacing of 

 flexible materials, such as rushes, bark-fibers, and 

 long blades of grass. It is a basket- weaver's job, 

 with a framework of reeds as a basis for the struc- 

 ture. Finally, in this basket, which is made much 

 longer than wide, is placed the nest proper, a warm 

 little bed of cotton-like down, spiders' webs, and 

 wool. 



"But this abode resting on piles above the water is 

 exposed to two dangers, — the swaying of the reeds 

 which, bent over by the wind, might incline the nest 

 so that it would spill its contents either of eggs or 

 of young birds; and secondly, the spring freshets, 

 which might rise so high as to submerge the nest. 

 These dangers, however, have been foreseen by the 



