146 The Wilson Bulletin — No. 88 



strands (40-60 mm.) of rather coarse gray hair, and longer 

 strands (150-200 nnn.) of somewhat finer auburn hair, seemed 

 to indicate two sources of material. There were a very few 

 still coarser black hairs, which may have been horse hairs. 



The presence of this material in the Pine Siskin's nest is 

 of interest and significance. This bird is accustomed to nest 

 in localities Avhere such material is probably not available. 

 We find here, then, an instance of its abilit}^ and readiness 

 to adapt itself to new surroundings and conditions of 

 environment. 



This pair of birds was evidently overtaken witli the breed- 

 ing instinct before the bulk of the species had moved north- 

 ward from this locality. Finding a suitable site in the spruce 

 trees, no doubt accentuated the developing instinct. Con- 

 struction was begun, and a foundation of the normal type wa.s 

 built from the pine twigs. Then in searching for the softer 

 material in the immediate vicinity, which included a human 

 liabitation, they came across a supply of human hair, which 

 they were able to recognize as suitable for their purpose. 



There are, in this instance, two notcAvorthy facts. The 

 establishment of a record of the breeding of the Pine Siskin 

 in the state of Iowa ; and the interesting modifiability of habit 

 in response to external conditions. 



Sioux City, Iowa. 



