150 SKETCHES OF BIRD LIFE. 



used vary according to circumstances, and are some- 

 times replaced by materials which, from their colour 

 or appearance at a distance, serve more effectually 

 to conceal the nest from view. Thus at White- 

 house, near Belfast, as recorded by Thompson, the 

 Chaffinches which built in the neighbourhood of 

 two cotton-mills always made use of cotton in the 

 construction of their nests. The mills were a 

 quarter of a mile distant from each other, and all 

 the nests of these birds erected in the intervening 

 plantations, as well as in the immediate vicinity of 

 the mills, exhibited the foreign product, not only as 

 lining, but exteriorly. One would have supposed 

 that its conspicuous colour would have betrayed 

 the presence of the nests, and thus disturb the 

 theory that birds select materials for their nests 

 which assimilate in colour to the objects by which 

 they are surrounded ; but it appeared on inquiry 

 that in the locality in question the use of the cotton 

 tended rather to aid concealment, as the roadside 

 hedges and neighbouring trees were always dotted 

 with tufts of it. The nest is always an open, cup- 

 shaped structure, generally placed upon the branch 

 of a tree close to the stem, sometimes with the stem 



