1921 BIRDS OP MONTANA 103 



of the I'oothills. It is eouiiiion throughout tlie Transition zone, and is found in 

 the Canadian, where areas suited to it occur in that zone. It is common in White- 

 tail Park, Jefferson County, a large grass area within the Canadian zone, situ- 

 ated at an elevation of 7100 feet. 



The migrations take place in late ^larch or early April, and in October or 

 November. West of the divide it is so common in winter that migration dates 

 cannot be determined with certainty. In Custer County, eighteen years give an 

 average arrival of March 30, with the earliest, March 20 (1907), while the aver- 

 age of fall dates is October 20 (Cameron, 1907, p. 399). Other dates are: 

 Bozeman, March 19, 1909, and ]\Iarch 19, 1911 ; Helena, March 20. 1911 ; Clio- 

 teau, April 4, 1912; Highwood, March 27, 1914; Button, April 11, 1915, March 

 17, 1916, and April 6, 1917 (DuBois, MS). Fall dates are: Bozeman, November 

 17, 1908; Three Forks, October 17, 1909; Button. October 11. 1916 (Bubois, ]\IS). 



The Western ^leadowlark is a regular winter bird in the lower valleys west 

 of the continental divide, such as the Bitterroot Valley and the valley of the 

 Flathead River about Kalispell. East of the divide it occurs in winter in scat- 

 tered localities and in small numbers. It is reported to winter in Custer ( 'Ounty 

 (Cameron, 1907, p. 400), in Gallatin County (Saunders. 1911a, p. 40^ at Helena 

 (Saunders, 1911b, p. 108), and at Billings (Thomas, .MS). 



Nesting begins the latter half of May. and eggs may be found from then 

 until late June. Young are leaving the nests from the middle of -June until 

 early in August. Whether there are two broods or not is not apparent, as there 

 seems to be no general break in the finding of eggs. The earliest nest on record 

 is one from the Bitterroot Valley, May 12, 1911, and tlie latest record of nesting 

 is that of young unable to fly, August 10, 1908, in the same locality (Bailey, 

 MS). The latest eggs are June 28, 1874, on Porcupine Creek (Coues, 1874b, [>. 

 603), but it is probable that eggs may be found much later than this. 



198. Icterus galbula (Linnaeus) 



Baltimore Oriole 

 A rare summer resident of extreme eastern Montana. Tliree specimens 

 were taken by Br. Hayden on the Yellowstone and at the mouth of the Powder 

 River in 1856, one of w^hich is dated August 4 (Baird, 1858, p. 549). Mr. 

 Thomas wrote me that he saw a bird of this species at Glendive in August, 1909. 

 These appear to be the only records. 



199. Icterus buUocki (Swainson) 



Bullock Oriole 



A summer resident of the prairies and lower mountain valleys, breeding in 

 Cottonwood groves along streams, mainly in the Upper Sonoran zone. Common 

 in eastern JMontana, and becoming rare westward, but found throughout the 

 state in suitable localities. Rare at elevations above 4000 feet in the northern 

 part of the state, and above 4500 in the southern. Because of this, this species 

 is not recorded from southwestern ^lontana west of Gallatin County, where the 

 valleys are nearly all above 4500 feet. The only place where I have found it 



