5 o SPRING 



stroyed the wrens that did not acquire this advantageous habit. 

 But further observation shows that if this is the lesson which 

 nature means the wrens to learn, they have not yet fully learnt 

 it. Nests of moss can be found fitted into the crevices of a 

 grey stone wall, where they are distinctly conspicuous ; and 

 by no means all the nests hung among creepers or brushwood 

 are built of materials resembling their surroundings. It seems, 

 after all, that the cases of close resemblance simply arise from 

 the bird using the material which comes nearest. Thus nests 

 among fern are often built of fern leaves, and nests among 

 mossy stumps of moss. 



As April advances, the beautiful nests of the chaffinch and 

 long-tailed titmouse face us with the same problem in a rather 

 different form. The large oval nest of the long-tailed tit is 

 always brightly spangled with white lichens ; and the hardly 

 less beautiful cup of the chaffinch's nest has the same decora- 

 tion, though not invariably. When either of these nests is 

 built in the fork of a lichened bough, or against a hoary 

 trunk, the protective resemblance is very close and effective. 

 But we generally find long-tailed tits' nests hanging among 

 the bare April thorns and chaffinches' among twigs not 

 covered with lichen, or in the green branches of gorse or fir ; 

 and in such situations the coating of lichen makes them 

 additionally conspicuous. Here, too, there seems to be no 

 originally protective purpose in the birds' habit ; the chaffinch 

 and long-tailed tit appear to ornament their nests with silver 

 lichens for the sake of their beauty, just as the bower-birds 

 collect blossoms and shells to decorate their courting-places, 

 and kites prank their nest with rags. 



The long-tailed tit is the earliest nester of its tribe, and 

 sometimes begins to build before the end of March. Other 

 tits wait until the unmistakable week of spring which 

 usually occurs about the middle of the month, when grass 



