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150 PACIFIC COAST AVIFAUNA No. 14 



292. Geothlypis trichas occidentalis Brewster 



Western Yellovvtiiroat 



A very conmion summer resident in the western half of the state, east to the 

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

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

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

 Nests in thickets of willow, wild-rose and other similar shrubs, iii moist places 

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

 almost exactly coincident with that of the oMacGillivray Warbler, both being 

 found east to Fergus County and the INInsselshell River, but the Yellowthroat 

 is much commoner at low elevations in valleys, and much less common in the 

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

 gether. 



The migrations take place in May and September. At Great J^'alls and 

 Columbia Falls the Western Yellowthroat arrives during the second week in 

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

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

 20, 1911, May 12, 1912, and May 28, 1918 (Bailey, MS). The only fall date T 

 have is from Gold Creek, Sei)teml)er 21, 1910. In eastern Montana, where it 

 occurs only in migration, it has been taken at Fort Keogh in spring (Thorne, 

 1895, p. 218). 



While this species undoubtedly nests very commonly, there is only 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 l)elieve that 

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

 out of the nest commonly early in July, and found one such \oung bird, at 

 Homestake, Jefferson County, in late June. 



293. Icteria virens longicauda Lawrence 



Long-tailed Chat 



A common siunmei- resident in eastern ^Montana, occurring rarely also west- 

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

 of the prairie region, and evidently liecomes rare north of the ^lissouri River. 

 West of the center of the state it occurs en-atically, being found for a year oi- so 

 in certain localities, but not persisting there. Tn the eastern part of th(> state 

 it is evidently found chiefly in the Cpper Sonoran zone, but in the western part It 

 sometimes occurs in the Transition. It evidently breeds in thickets of shi'ubs, 

 such as wild-rose, thorn and gooselx^i-ry. The western limits of its couuuon 

 range are Fergus County (Silloway, 1903a. |). (if)) jind the .Musselshell River 

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

 Ravalli). IMissoula County, June l(i. 1900, l)eginning nestinir (Silloway, lOOla, 

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

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

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



