Nov., 1922 THE DEVELOPMENT OF YOUNG COSTA HUMMINGBIRDS 191 
wards sitting there for some time until the prezumably rightful owner presently 
darted at the intruder and drove her away. The nest was composed largely of 
small achenes bearing soft pappus. Other items noted were fibers, minute leaves, 
feathers and a short piece of string, the whole bound securely to the branch with 
cobwebs. 
One egg was found in this nest on the afternoon of June 6 and another the 
next morning, this before the walls of the nest were entirely filled in. The nest 
was by no means considered complete with the laying of the eggs, but additional 
material was constantly brought, so that at times the eggs were almost con- 
eealed by it. After 14 or 15 days’ incubation the bird disappeared from the 
nest and was seen no more, at least in that vicinity. 
The behavior of the hummingbird on the uest is directly opposite to that of 
many other birds. It does not remain motionless in the hope of escaping notice, 
Fig. 47. Youne Costa HUMMINGBIRDS IN NEST (NO. 1). Azusa, May 18, 
- £921, 
but often flies when approached within 30 or 40 feet. If one stands quietly even 
at a much less distance it will soon return, to leave again at any sudden motion. 
Thus the idea of concealment of the location of its nest does not enter into its 
thoughts or instincts. Those nests which I have found have been so situated that 
a clear outlook could be obtained in at least two directions. The hummingbird 
while incubating seems to require but little time for procuring food, as I have 
seldom found them absent from their eggs, and of course the female is not re- 
lieved by her mate, as is the case with so many birds, nor is she fed by him as 
are the female finches. The owner of the nest shown in figure 49 was more shy 
than usual and it was necessary in securing the photograph to remain at some 
distance, operating the shutter with a thread while reflecting light on the sub- 
