Nesting Behavior of the Yellow Warbler. 51 



one, the blind was moved a little nearer to the nest in order 

 to gradually accustom the birds to its presence. Upon visit- 

 ing the nest on the morning of July 2, at 7 :30, it was found 

 that three of the eggs had hatched, and the young, evidently, 

 were but a few hours old. The blind was now brought to 

 within two feet of the nest ; during this operation the parents 

 continued to feed the nestlings. At 4 :15 p. m. of the same 

 day the blind was entered and observations began, which were 

 continued as described elsewhere. On July 5 the blind was 

 moved six or seven inches nearer the nest so as to get a bet- 

 ter view of the feedings and distinguish the young. 



Incubation Period. 

 The last egg hatched at 5 :30 a. m. on July 3 ; while the 

 fourth egg was first observed in the nest at 11 :30 a. m. on 

 June 22. Between these two dates ten days and six hours 

 are counted. It is taken for granted that the egg was laid 

 earlier in the day, perhaps, between four and six o'clock. By 

 adding this calculated six hours, the incubation period would 

 appear to be just about even eleven days. 



Hatching. 

 At about 5 :30 a. m. on July 3 the writer was attracted by 

 a peculiar rolling motion of the egg in the nest, and noticed 

 upon closer observation, that the shell bulged out in a ring 

 around the middle or a little nearer the smaller end ; and soon 

 it began to crack at this place. The egg raised on the small 

 end, leaning against the side of the nest, and the young bird 

 freed himself from the shell by a series of pushes and kicks 

 by the head and feet, respectively. The head escaped from 

 the larger part of the shell and the lower part of the body 

 from the smaller end. The crown of the head and the me- 

 dian line of the back of the nestling were downy. This en- 

 tire process covered a period of less than four minutes. 



Disposal of the Shell. ^' ''^> \'\-%i^ 



The female, bringing a grasshopper, returned to the nest 



immediately after the hatching of the fourth egg. She fed 



