252 U. S. NATIONAL MUSEUM BULLETIN 211 



tightly than others. I do not wish to imply that the same thread that is first 

 thrust through the nest mass or the nest wall is immediately drawn back, but 

 only that some thread or other is blindly seized by the bill and withdrawn. * * * 

 The irregularity of the weave of the finished work shows conclusively that the 

 stitching is a purely random affair, though, for all that, none the less effective. 



Thus in the course of 2 or 3 days' work, a loose, tangled mass of 

 fibers, which will ultimately become one side of the nest, hangs from 

 the supporting twigs. Many long strands dangle from this mass, 

 their ends hanging free. When this stage of the construction is 

 reached, the bird, working from what is to become the inside of the 

 nest, and as Herrick describes her actions, working with "decision 

 and feverish rapidity, with strokes of her bill pushing the threads 

 through the nest body and then catching up the free ends of other 

 strands and drawing them in the opposite direction; with one foot 

 grasping a twig and the other the nest mass, thrusting and pulling, 

 she is now astride the mass and balancing herself with spread wings, 

 now working from above, from below, or at either side; and at each 

 visit she is not only incorporating any new strands that are brought, 

 but gathering up many others which, though fixed at one end, are still 

 hanging free." 



Finally, the bird takes in another twig, or other twigs, for support, 

 outlines the framework of the other side, and then fills it in by weaving 

 with the shuttle movements as before. The long streamers are 

 ultimately worked into the wall of the nest. Herrick speaks of the 

 finished nest as "an indescribable chaos of looped and knotted fibers" 

 that is, nevertheless, "strong, durable, and adaptive." In construct- 

 ing these nests "the female was the chief builder, but the male would 

 occasionally take a share." 



In the late stages of construction "the bird settles down in the nest 

 and shakes all over in an effort to bring the pressure of the breast to 

 bear upon its inner surface; he [in this case the bird was assumed to 

 be the male] rises, turns, settles, and shakes again. These are the 

 typical molding movements, and they are applied all over the lower 

 parts of the pouch, their violence at times being such that the sur- 

 rounding leaves, and even the slender tree itself, are all a-tremble." 



One of Herrick's nests was completed in 4% days. Harry C. Ober- 

 holser (1938) sa3^s the nest "is usually completed in not more than 6 

 days"; Bendire (1895) says: "From 5 to 8 days are usually required 

 for its completion"; while Knight (1908) states that "nest building 

 requires about 15 days." 



The oriole begins to build so soon after its arrival on its breeding 

 ground that the elms, a favorite tree, are barely leafing out when the 

 nest is building. But soon, as the season advances, the leaves afford 

 both protection and some concealment to the nest. In January 1946 



