376 BULLETIN 197, UNITED STATES NATIONAL MUSEUJV 



noted, besides the dry grass blades and stems already mentioned : Three pieces 

 of white string, 14, 15, and 241/^ inches in length, respectively; also a number 

 of small white threads of various lengths up to 6^2 inches; 35 detachable bits 

 of down from willow seeds, with many woven in securely; several bits of lichen 

 (Alectoria fremontii) ; small strips of ninebark (Opulaster pmiciflorus) ; three 

 small pieces of old discolored cotton ; and, in the rim, bits of matted cow hair. 

 There being four houses less than one hundred yards from the nesting site, 

 the string, horsehair and cotton were no doubt obtained on or near those premises. 

 The balance of the material could have been secured a few feet from the nest. 

 In weaving the long piece of string, one end must have dropped down, and in 

 picking up the loose end it had been passed under a small twig below the nest, 

 forming a long hanging loop that remained in place during the occupancy of 

 the nest, as shown in the photos. 



The bulk of the nest, if not the entire structure, was built by the female. The 

 male remained in nearby trees, singing at regular intervals, but he was not 

 noted helping at any time. As in the case of the former nest, several days 

 passed after it was finished before any eggs were laid. The first egg in the 

 second nest was noted on June 4. Visited late in the afternoon of the 7th, the 

 nest contained four eggs, the complete set. 



The young willow in which the nest was placed was growing in a small opening 

 about thirty feet from the edge of the old road, and was surrounded by a 

 profusion of green shrubbery that was much to the liking of the vireos. On 

 only two occasions did I note either of the parent birds more than forty yards 

 away from tlie willow after the nest was completed, until the young bad flown. 

 I could not help but note the pretty setting for such an interesting bit of home 

 life. The ground was carpeted with a thick growth of wild sweet pea (Lathyrus 

 panciflonis) which was in full bloom and scenting the air with a sweet odor. 

 One side of the opening was enclosed with buckbrush {Ceanothus sanguineus) 

 and ninebark in bloom ; beyond there were several large yellow pines and Douglas 

 fir trees ; on the other side were service berry bushes, willows, and ocean spray 

 {Schizonoiiis discolor) which extended to a large grove of pine and fir trees in 

 the near distance. In and out through the surroundings were bushes of the 

 large flowering wild rose in full bloom, adding a touch of color to the masses of 

 green and white. 



It will be observed from the above records tliat the western warbling 

 vireo differs decidedly, in its choice of a nesting site, from its eastern 

 relative. The eastern bird builds its nest almost invariably in trees 

 and at a very considerable height, whereas the western bird often 

 builds in bushes or low trees and much nearer the ground. Most of 

 the recorded nests of the western warbling vireo have been placed at 

 not over 12 feet from the ground : and its highest nests, which seem to 

 be exceptional, have been below the average for the eastern bird. 



Eggs. — The western warbling vireo lays from three to five eggs, 

 usually four. These are quite indistinguishable from those of the 

 eastern race. The measurements of 40 eggs in the United States Na- 

 tional Museum average 18.4 by 13.2 millimeters ; the eggs showing the 

 four extremes measure 20.3 by 14.7, 20.1 by 15.0, and 16.8 by 12.2 

 millimeters. 



Young. — Mr. Rust (1920) found that the period of incubation was 

 12 days, performed by both sexes. "If my visit happened in the morn- 

 ing, and the male was incubating, I could almost touch the nest before 



