538 ANIMAL LIFE IN THE YOSEMITE 



at the end of June. Eg-gs are laid on successive days, incubation begins 

 immediately upon the laying of the last egg or possibly before, and is 

 completed in 13 days, the young hatch on the same day, or on two succes- 

 sive days, and leave the nest 8 or 9 da3^s after hatching. The male seems 

 to participate but little in caring for the brood. 



Yellowtiiroats. Geothlypis trichas (Linnaeus) -^^ 



Field characters. — About half size of Junco. Adult male: Forehead and face crossed 

 by a broad band or mask of black, bounded above by white; throat and most of under 

 surface clear yellow; upper surface of body yellowish brown. (See pi. 9i.) Female 

 and young: Yellowish brown above, yellowish white beneath. An active yet reclusive 

 species. Voice : Song of male a set theme given three or four times in slow rhythm with 

 rather insistent delivery, wretch' -et-y, wretch' -ct-y, wretch' -et-y; call note a sharp yet 

 hoarse-sounding tchaclc. 



Occurrence. — Common resident at Snelling and below Lagrange (subspecies scirpi- 

 cold). Transient along both flanks of Sierra Nevada and summer visitant at Mono Lake 

 (subspecies occidentalis) .^5 Lives low in tule marshes and shrubbery bordering streams. 

 Solitary or in pairs. 



The Yellowthroats are birds of marshy places and so are found in 

 numbers at both ends of the Yosemite section, but they are of only casual 

 occurrence elsewhere in the region. Individuals pass through the western 

 foothill country during the migrations. A male bird was noted by us 

 May 29, 1911, in Yosemite Valley near Stoneman Bridge ; and two birds 

 were noted in Yosemite Valley on the morning of September 29, 1917 

 (Mailliard, 1918, p. 16). The lack of suitable cover in the form of dense 

 thickets of willow or of tules probably accounts for the failure of the birds 

 to remain there throughout the summer. 



The YelloM'throats found at Snelling and Lagrange (subspecies scirpi- 

 cola) are the only really resident members of the whole warbler family 

 in the Yosemite section. Suitable forage and cover are evidently sufficient 

 there at all seasons; they remain in full numbers throughout the colder 

 portion of the year. At Snelling 10 were noted in tangles of blackberry, 

 nettles and willows during a 2i/2-hour census on January 6, 1915. Eight 

 were recorded in similar cover at that place during a 3-hour trip on 

 May 26 ; and on May 29 the same year not less than 18 of the birds were 

 noted during an hour and a half in particularly favorable country. 



35 Two closely similar subspecies of Yellowthroat occur in the Yosemite section. 



Western Yellowthroat, Geothlypis trichas occidentalis Brewster, a smaller duller 

 colored race summering in the Great Basin and the Northwest, a transient along both 

 flanks of the Sierra Nevada, and a summer visitant about Mono Lake. It has occurred 

 in the fall migration at Smith Creek, cast of Coulterville, and in spring and fall in 

 Yosemite Valley. 



Tule Yellowthroat, Geothlypis trichas scirpicola Griunell, a larger, longer tailed 

 and more brightly colored subspecies, resident in the San Joaquin Valley and in southern 

 California, was found in both winter and summer at Snelling and near Lagrange. 



