\ 



144 PACIFIC COAST AVIFAUNA No. 14 



ward with swainsom. Recorded as follows : Fort Keogli, breeds, young taken 

 July 24 (Thorne, 1895, p. 218) ; Custer and Dawson counties, common migrant, 

 noted 31ay 16, 1899 (Cameron, 1908a, p. 49) ; .Miles City, six skins dated from 

 .May 11 to June 8, 1902 (Hedges, coll. Univ. Montana). The last mentioned spe- 

 cimens have recently been compared by Dr. Bishop and myself witli liirds in the 

 former's collection. They are typical of the eastern race. 



273. Vireosylva gilva swainsoni (Baird) 



Western Warbling Vireo 



A common summer resident throughout the western part of the state, inte)-- 

 grading eastward, in the prairie region, w^ith gilva. Breeds in cottonwood groves 

 of the prairie region and mountain valleys, and in aspen groves of the moun 

 tains, in the Transition and C'anadian zones. Occurring up to 7000 feet in \\\r 

 southern part of the state, and to 6500 in the northern. Reported by all ob- 

 servers, and one of the commonest summer birds in tlie mountains, where it is 

 particularly characteristic of the aspen groves. 



The migrations take place in ]\Iay and August, the species arriving about th<' 

 middle of I\Iay at low elevations, but in the mountains often not until Jmie. At 

 (.'olumbia Falls, three years give jMay 16 for the average and May 14, 1895, the 

 earliest (Cooke, 1909b, p. 80). Other dates are Bozeman, June 1, 1909; German 

 Gulch, Silver Bow County, May 28, 1910; Bozeman, May 28, 1911; Bitterroot 

 V^alley, May 6, 1911 (Bailey, MS). Fall dates are: Bozeuum. August 10, 1908, 

 ;ind August 16, 1909; Gold Creek, Powell County, August 27, 1910; Belton, Aug- 

 ust 27, 1915 (DuBois, MS). 



Nesting takes place in June and July. The earliest nest on record is one 

 at Flathead Lake containing three fresh eggs June 15, 1900. Another at tliis 

 same locality contained three young June 23, 1900 (Silloway, 1901a, p. 19). 

 The latest nest I have record of is one on Little Pipestone Creek, Jefferson Coun- 

 ty, which contained four eggs July 13, 1910. 



274. Lanivireo solitarius cassini (Xautus) 



CaSSIN VlREO 



A summer resident in the northwestern part of the state, west of the con- 

 tinental divide, occurring rarely in migration east of the divide in the moun- 

 tains. Breeds chiefly in tlie Transition, in Douglas fir and tamarack forests. 

 Records: First reported from the state from Columl)ia Falls (Cooke, 1909b, p. 

 168), where the average arrival is April 28, the earliest April 26, 1895, and a 

 date of fall migration, September 12, 1895. Breeds at Flathead Lake commonly 

 (Saunders, 1915b, p. 111). A nest at Yellow Bay, Flathead Lake, found jiartly 

 huilt June 22, 1916. The young flew July 25 (Sloanaker, MS). Taken at 6000 

 ieet near Corvallis, September 10, 1909, by Vernon Bailey (Bailey, MS). Sev- 

 eral seen on Willow ('reek, Powell County, September 12 aiui 1.'?, 1910 (S;nm 

 ders, 1912a, p. 30). One seen on the West Fork of the Sun River, east of the 

 continental divide, September 3, 1912 (Saunders, 1914a, p. Ml"). 



