I'j21 BIRDS OF MONTANA 11 



through the writings of early explorers. It is characterized mainly by the ab- 

 sence of certain species, rather than by the presence of new ones. All those 

 mentioned as characteristic of the southern prairie region are lacking or rare 

 here. The region differs from the northwestern prairies by the presence of sage- 

 brush and of the Sage Hen and perhaps other sage-loving species. It also differ.-; 

 in the rarity and perhaps entire lack of the Sprague Pipit and Baird Sparrow, 

 these species being found l)oth east of this region in North Dakota and west of it 

 in the northwestern prairie region (Cones, 1874b, pp. 559-563). It differs ma- 

 terially from the southern prairie region in the greater abundance of ducks and 

 other breeding water birds, especially along the Milk River. 



The northwestern prairie region occupies the western half of Choteau and 

 Fergus counties, nearly all of Toole, Teton and Cascade counties, and the north- 

 eastern corner of Lewis and Clark county. It differs from both the other prairie 

 regions in the entire absence of sage-brush and therefore of such sage-loving spe- 

 cies as the Sage Hen. It lacks the species characteristic of the southern prairies 

 but is enriched by a greater abundance of water birds, such as ducks, grebes, 

 avocets and phalaropes, and by the abundance of the Sprague Pipit, and by the 

 occurrence of the Baird Sparrow^ as a breeding bird. 



Like the prairies, the mountain region may be divided into three faunal 

 areas, the southern, northeastern and northwestern. In each of these three re- 

 gions a division of the areas into mountains and mountain valleys is at once ap- 

 parent. The mountain valleys are flat or rolling country, from 8,000 to 5,000 

 feet in altitude, treeless except along the borders of streams, and in many re- 

 spects similar in character to the prairie region. The mountains are for the most 

 part timbered with coniferous forests and broken into high ridges and peaks, 

 steep slopes and deep steep-sided canyons. They begin at from 3,000 to 5,000 

 feet, and extend up to 11,000 feet in some places. 



The southern mountain region extends from the western limit of tlie south- 

 ern p.rairie region in Carbon and Sweet Grass counties, westward to the western 

 border of the state, and northward to include western ^leagher and Broadwater 

 counties and southern Powell County. The Big Horn Mountains and other 

 smaller areas isolated within the prairie region may also be considered outlying 

 portions of this region. The region crosses the continental divide in Silver Bow, 

 Deer Lodge and Powell counties, the divide here having little effect on the fauna. 

 Whether it should be extended to include Granite and Ravalli counties is uncer- 

 tain. The birds of Ravalli County show a condition rather intermediate between 

 the southern and northwestern mountain regions. The southern mountain re- 

 gion is characterized by southern species, such as the Williamson Sapsucker and 

 the Green-tailed Towhee. The breeding range of the Pink-sided Junco defines 

 it well . 



The northeastern mountain region occupies a narrow strip of country west 

 of the prairies and east of the continental divide. It includes most of Lewis and 

 Clark County, and the mountainous portions of Cascade and Teton counties. It 

 is characterized by lack of the southern and western forms of the other moun- 

 tain regions, and hy the; breeding in small numbers of such northern species as 



