166 PACIFIC COAST AVIFAUNA No. 14 



it is the eoiiDiionest species i'oimd on the shores of Flathead Lake. Breeds in tin' 

 Transition and Canadian zones, in coniferous forests or in forests of eonilVrs 

 and broad-leaf trees mixed. Occurs in migration in the eastern part of the state, 

 where it is regular but not common. The easternmost records of its breeding 

 ;irc from the P>elt Mountains (Williams, ISDOh, p. 292), the mountains of Fergus 

 County (Sillovvay, 1903a, p. 69), and the Hig Horn Mountains (McChcsney, 

 1S79. p. 2:^84). 



The migrations take place in May and September. Dates of spring migra- 

 tion in portions of the state where it does not breed are as follows: Custer Coun- 

 ty, May 31, 1906 (Cameron, 1908a, p. 55) ; Miles City and vicinity, May 11 to 

 June 7, 1902, thirteen specimens (Hedges, coll. Univ. Montana). In regions 

 where this species breeds it nrrivi-s nbout the middle of May. Three years at 



Fig. 34. Nest and eggs of the Olive-b.\cked Thrush. Yellow Bay, 

 Flathead Lake; June 29, 1914. 



Great Falls, give an average of May 15, and tlie earliest Jlay 3, 1892; three years 

 at Columliia Falls average May 19, the earliest JMay 17, 1896 (Cooke, 1907, p. 

 122). In the Belt Mountains it is said to arrive May 10 (Williams, 1890b, p. 

 292). Other dates are : Bozeman, June 1, 1909 ; Norton Gulch, Silver Bow Couu- 

 t.v, May 16, 1910; Anaconda, May 14, 1911 ; Choteau, May 22, 1912; Teton River, 

 l\Iay 28, 1915; and Button. May 27-June 4, 1916 (DuBois, MS). Fall migration 

 takes place from September 1 to October 10 (Williams, 1890b, p. 294). The lat- 

 est date at Columbia Falls is September 23, 1895 (Cooke, 1907, p. 124). The 

 only other definite fall date I know of is from Sun River, September 4, 1912. 



Nesting begins about the middle of June, and eggs may be found from then 

 until the middle of July. The earliest date for a complete set of eggs is Jane 

 ]1. 191)0 (Silloway, liKlla. p. 10), and 1h<' latest is July 19. 1902 (Silloway. 



