150 PACIFIC COAST AVIFAUNA No. 14 



292. Geothlypis trichas occidentalis lirewstei' 



Western Yellowthroat 



A very fonuiion suiiinicr resident in the western half of the state, east to the 

 western part of the prairie region. Apparently rare in the more eastern part of 

 the prairie region, and occurring there only in migration. B.reeds throughout 

 the Transition zone, on the prairies, and in the mountain valleys and foothills. 

 Nests in thickets of willow, wild-rose and other similar sl-rubs, in moist places 

 along streams. The breeding range of the Western Yellowthroat in Montana is 

 nlmost exactly coincident with that of the JIacGillivray Warbler, both being 

 found east to Fergus County and the ^Iiisselshell River, but the Yellowthroat 

 is much cominoner at low elevations in valleys, and ;nuch less common in tlio 

 mountain foothills. In many localities, however, the two species are found to- 

 gether. 



The migrations take place in May and September. At Great Falls and 

 Cohunbia Falls the Western Yellowthroat arrives during the second week in 

 May (Cooke, 1904a. p. 119). Other dates are: Sedan. Gallatin County, May 21. 

 1909; Silver Bow, May 21, 1911 ; Choteau, May 19. 1912; Bitterroot Valley. May 

 20, 1911, Jlay 12, 1912, and May 28, 1913 (Bailey. IMS). The only fall date I 

 liave is fi'om Gold Creek. September 21. 1910. In ea.stern ^lontana. where it 

 (ii'cnrs only in migration, it has been taken at Fort Keogh in spring (Thorne, 

 1895, p. 21S). 



While this species undoubtedly nests very commonly, there is onl.v one rec- 

 ord of the taking of eggs in the state. This pertains to a set of four fresh eggs 

 taken at Flathead Lake, June 29, 1901 (Silloway. 1901a, p. 34), I believe that 

 this date is a little later than that of the average nest, for I have noted young 

 out of the nest commonly early in July, and found one such .young bird, at 

 Homestake. Jefferson County, in late June. 



293. Icteria virens lons^cauda Lawrence 



Long-tailed Chat 



A conmion siunmer resident in eastern ^Montana, occurring rarely also west- 

 ward to the western limits of the state. It is common only in the eastern part 

 01 the prairie region, and evidently becomes rare north of the Missouri River. 

 West of the center of the state it occurs erratically, being found for a year or so 

 in certain localities, but not persisting there. In the eastern part of the state 

 it is evidentl.v found chiefly in the Upper Sonoran zone, but in the western part it 

 sometimes occurs in the Transition. It evidently breeds in thickets of .shrubs, 

 such as wild-rose, thorn and gooseberiy. The western limits of its common 

 range are Fergus County (Silloway. 1903a, p. 65) and the Musselshell River 

 (Allen. 1874, p. 52). Records west of this point are as follows: Selish (now 

 Ravalli). Jlissoula County, June 16. 1900. beginning nesting (Silloway, 1901a. 

 p. 70) ; Big Fork, Flathead Lake, summer of 1903 (Silloway, 1904a, p. 12) ; Gal- 

 latin Valley, seen a number of times, one season only (Lundwall, MS) : and 

 Collins, Teton County, two, June 4. 1916 (DuBois, MS). 



