352 FRANCIS H. HERRICK 



bill. Twice I saw this bird bring in a wisp of spiders' silk, 

 and after getting it under one foot, draw out its filDres repeat- 

 edly with her bill, and not only pass them over the t\A'ig, but 

 secure each end in succession to the nest mass. This silk was 

 commonly carried in the mouth, and in such small quantities 

 that none showed when the bill was closed. It was withdrawn 

 wet, and when thus engaged, the bird would at times open her 

 mouth very wide, as if the more readily to be rid of it. The 

 saliva in this species has no marked viscous character, but pos- 

 sibly aids slightly in the treatment of the materials used. Many 

 no doubt would describe the act of pulling out the silk as "de- 

 liberately spinning a thread" for a definite purpose. I regard 

 it as strictly analogous to stripping bark and pulling at the 

 frayed ends of any fibrous material, with the exception of the 

 use of the foot, which is so unusual in passerine birds that it 

 may be simply the result of individual experience ; the use of the 

 mailed foot in all preying species like the eagle and hawk, whether 

 for striking, seizing or holding is primarily instinctive. 



The song of the male vireo was often heard during the entire 

 progress of nest-building. Twice only, as already noted, was 

 he seen to bring building materials, and twice he came up be- 

 hind the female and pecked at her as if in admonition to hurry 

 the work. A somewhat similar observation has been recorded 

 in the European swift. At a very early stage the female would 

 try to sit on the beginnings of her labor, but the loose fibrous 

 mass could not of course hold her, and dropping down she would 

 always catch ^\dth spread ^^ings on the V-shaped crotch. These 

 attempts were frequently repeated until on the second day 

 she was able to hold to the structure and press with her breast 

 against its thin wall. It was common to see her stand at the 

 angle and reaching far down peck daintily at the loose mass, 

 fixing a fibre here, securing another there, but always working 

 rapidly and as we say without "hesitation." 



During the first da}" of this vireo 's work the most striking 

 facts noted were as follows: (i) winding silk and fine bast over 

 the twigs at points about an inch from the angle of the crotch; 

 (2) building downward upon these a loose mass of fiber, perfectly 

 secured but having no resemblance to the future cup-shaped 

 nest; (3) carr3dng the suspension forward, and downward and out- 

 ward at either side of the nest-mass, which gradually takes the form 



