THE BUILDERS 49 



than three weeks was finally completed by a lining of 

 feathers, and was apparently ready for eggs when we left the 

 neighbourhood. Probably there is no absolute distinction 

 between the two kinds of nest, but the growth of the nursery 

 out of the bower or playground is still recalled by occasional 

 combinations of the two purposes. 



All the first nests of the year either dispense with con- 

 cealment as ostentatiously as the rook's or magpie's, or attain 

 it by being built inside holes or thick cover. The stock-dove 

 and wood-owl hide their white eggs in holes, and most black- 

 birds and thrushes secure fair protection in an evergreen bush 

 or in the fork of thick boughs. Others seem absolutely care- 

 less, and their eggs and young are usually destroyed by bird- 

 nesting boys or animals, or by the fear of the bird itself to 

 incubate in the publicity which it seemed to court when 

 building. But soon nests appear which display an exquisite 

 harmony with their surroundings, so as to elude all but the 

 sharpest or luckiest eyes, and to delight them when they know 

 the secret. Many wrens' nests are wonderfully elusive in 

 situation and structure. Sometimes they are hung among 

 dead bracken supported by brambles, with the nest half 

 shrouded by dried fronds, and built externally of similar frag- 

 ments of fern. Sometimes a few large growing leaves of the 

 bramble are used to hide the nest in the same way. When 

 the nest is hung among ivy, a few dead ivy leaves may be 

 worked into the shell of moss, so as to assimilate its fabric 

 to the surroundings ; and when it is built in a crevice in a 

 mossy stump, it is almost sure to be built of moss. In such 

 cases as these, the protective resemblance is so close that it is 

 hard to avoid the conclusion that the birds make their nests 

 resemble their surroundings by pursuance of strong instinct, 

 if not by conscious art. If such an instinct of mimicry existed, 

 it would be due to natural selection having vigorously de- 



(1,821) ~ 



