410 University of California Puhlications in Zoology. [Vol. 7 



Meadow (8400 feet). Breeding in Upper Sonoran and possibly 

 higher. 



Habits. — Yellow warblers are not confined exclusively to the 

 willow thickets, and although they do not venture far from water 

 they often do make short excursions into the sagebrush. 



The species has at least two call-notes. One is very close to 

 the "chick" of the chipmunk, while the other, while it may be 

 transcribed by the same syllable, is much weaker. One female 

 uttered this second call-note and shortly afterward a male bird 

 with wings and tail spread came dashing into the tree. He went 

 away in a short time, but upon a second call returned. 



On June 11 a bird was seen collecting willow cotton. The 

 first nest was found on June 5 in a wild rose at Quinn River 

 Crossing. Willow bark was the main constituent of the nest, the 

 lining being of plant down, feathers and horsehair. A single 

 willow catkin had also been worked into it. The cavity was 

 42 mm. (I^^ig inches) in diameter and 38 mm. {1%q inches) 

 deep. The set of four eggs was complete. 



Another nest was discovered on June 16 at Big Creek Ranch. 

 It was located six feet above an irrigating ditch also in a wild- 

 rose bush. The cavity was 44 mm. (134 inches) in diameter and 

 nearly 50 mm. (2 inches) deep. Three eggs, incubation about 

 half completed, constituted the set. 



Males were twice observed feeding their mates. The female 

 followed the male bird and shook her wings, assuming a begging 

 attitude Avhicli was quite linnet-like in character, while the male 

 bird fed her two or three times. During this process the birds, 

 or perhaps only the female, gave utterance to a decidedly chip- 

 munk-like (Eutamias pictus) series of chatterings. Both these 

 birds were fully adult. Perhaps the female does not take time 

 to hunt food during the brooding period. 



A nest in process of construction was noted the same day a 

 few hundred feet farther down the thicket. It was saddled on a 

 wild-rose crotch, three feet above the ground. Shreds of willow- 

 bark were the most prominent building materials employed, these 

 being fastened together with spider web. 



