530 ANIMAL LIFE IX THE YOSEMITE 



immatures of both sexes share in common the white stripe above and 

 behind the eye, the white line from bill down side of throat, the two light 

 wing bars, the white margined tail and, best of all, the hiack streaking 

 on the sides of the otherwise pure white under surface. The back is bluish 

 gray in all, 



A striking similarity in markings exists between the Townsend and 

 the Black-throated Gray warblers. One is an exact replica of the other 

 save that the yellow of the former is replaced by white in the latter. This 

 parallelism extends to all ages and both sexes. The Townsend Warbler 

 is only a transient here. 



The Black-throated Gray ^Varbler arrives in the Yosemite region by 

 April; it was already present in Yosemite Valley on April 29, 1916. It 

 continues here until early fall, several being seen in company with some 

 Audubon Warblers, along the Glacier Point trail, on September 25, 1915, 

 The latest seasonal occurrence known is of a single bird recorded near 

 Feliciana Mountain southwest of El Portal, on October 30, 1915. East 

 of the mountains near Williams Butte two of these warblers, doubtless 

 migrants, were seen in a mountain mahogany bush on September 16, 1915, 



The population of this bird seems to fluctuate markedly from year to 

 year. During a 50-minute walk up the Yosemite Falls trail to Columbia 

 Point on June 4, 1915, 14 of these birds were recorded. A similar climb, 

 through the somewhat lighter growth on the Sierra Point trail. May 16, 

 1919, revealed only one singing male, and elsewhere in the Valley, in the 

 latter year, the numbers of this species were unusually small. 



The Black-throated Gray Warbler is not a particularly active species 

 and its slow movements combined mth a 'disruptive' pattern of coloration 

 sometimes render it difficult to see against the sunlit foliage of the oaks. 

 The bird inhabits largely the crovm and middle foliage and so does not 

 often come into plain view. The song of the Black-throated Gray Warbler 

 is a rather lazy, drawling utterance, deep-toned rather than shrill. Wee-zy, 

 wee-zy, wee-zy, wee-zy-weet ; tsewey, tsewey, tsewey, iseivey-tsew ; zuee, 

 zuee, zuee, soop; si-si-weezy, weezy we-tsv/ ; oweze-weze-weze-weze-chur, are 

 syllabifications written by us at different times when individual birds were 

 singing close at hand. There are modifications in the song; sometimes the 

 terminal syllable is omitted and again only three of the two-syllabled notes 

 are given. The ordinary call is a rather low, one-syllabled chit. 



Near Smith Creek, east of Coulterville, a nest of the Black-throated 

 Gray Warbler was seen on June 5, 1915. It was placed 5 feet 6 inches 

 above ground in a mountain lilac (Ceanothus integernmus) bush against 

 a main stem. Outside, the nest measured 214 inches both in diameter and 

 height. There were 4 young birds only 2 or 3 days old. Upon our 

 approach the female flushed and made off, with the brokon-wing ruse 



