COLIMA WARBLER 127 



Nesting. — Two nests, both in the Chisos Mountains, have been de- 

 scribed. The first (discovered in 1932) was lodged between small 

 rocks and deeply imbedded in dead oak leaves on the sloping bank 

 of a dry stream bed. A dense ground cover of vines and other her- 

 baceous plants arched completely over it, leaving an entrance only 

 on the northwest side, toward the stream. The nest had a basic struc- 

 ture of loosely woven fine grasses, the outside reinforced with pieces 

 of green moss and the rim with strips of cedar bark; the cavity (5 

 centimeters across the rim and 4 centimeters deep) was lined with 

 fine grass, a little fur, and a few hairs (Van Tyne, 1936). The other 

 nest, which was "on the ground, under a little bunch of oak leaves, 

 at the edge of a talus slope, almost at the very base of the cliffs" 

 (Sutton, 1935) , was similar, but its basic structure included dry leaves, 

 and the site was concealed by only a partial canopy of leaves (Van 

 Tyne and Sutton, 1937). 



Nest building was observed in the Chisos Mountains on May 7, 1932 

 (Van Tyne, 1936) : 



As I was crossing the dry stream bed about a hundred yards below Boot 

 Spring, I suddenly saw within twenty-five feet of me a female warbler with 

 nest material in her bill. I stopped instantly and, remaining motionless, was 

 greatly relieved to see the warbler continue undisturbed by my presence. In 

 a moment she dropped to the ground and entered the nest, which was on the 

 sloping right bank of the stream about sis feet back from the margin of the 

 rocky stream bed. After working for about twenty seconds the warbler left 

 the nest and flew down the stream bed a hundred and fifty feet. In twelve 

 minutes she was back mth more nest material to repeat the performance. 

 Subsequent excursions for building material during the ensuing hour were of 

 three, twelve, six, and twenty-two minutes' duration. Each time she worked 

 at the nest only fifteen to twenty seconds, until the last trip (at 11:43 A. M.) 

 when she worked about two minutes and then departed, probably to feed, for 

 she did not return again while I watched. Each trip to the nest had been made 

 undeviatingly, without any hesitation, from tlie stream bed or from the forest 

 to the west. Alighting almost directly above the nest, without a pause she 

 dropped through the branches by three or four stages and promptly entered the 

 nest, placed the material, and snuggled down working it into place. After a few 

 moments she seemed to have completed this to her satisfaction, and, leaving 

 the nest, she flew up to the branches ten or twelve feet above, fed for a few 

 moments on the insects among the fresh green leaves of the little oaks and 

 maples, and went away for more material. 



When it was evident that the nest building was over for the time I went over 

 to the nest and, examining it more closely, found that it was nearly built. The 

 following day. May 8, it seemed to be finished. 



Eggs. — Two complete clutches have been found, each containing 

 four eggs. Four eggs collected and measured were 18 by 13.3, 

 18 by 13.5, 18 by 13.5, and 18.5 by 14 millimeters. They were creamy 

 white, speckled, and blotched in a wreath at the larger end with 

 "vinaceous fawn," "light brownish drab," and "cijinamon drab," 



