Vj21 birds of MONTANA 11 



tliroutjli the writings of early explorers. It is eharaeterized mainly by ttie ab- 

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

 mentioned as characteristic of the southern prairie re.uion are lacking or rar^^ 

 here. The region differs from tlie northwestern [irairies by the presence of sage- 

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

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

 these species being found both east of this region in North Dakota and west of it 

 in the northwestern prairie region (Coues, 1874b, pp. 55n-r)(i:!). It diffei's ma- 

 terially from the southern prairie i-egion in the greater alnnidance of ducks and 

 other In-eeding water birds, especially along tlie ]\Iilk River. 



The northwestern prairie region occupies the w'estern half of Chotean 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 s]ie- 

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

 but is enriched by a greater abundance of water birds, sueli as ducks, grelies. 

 avocets and phalaropes, and l)y the abundance of the Sprague Pipit, and l)y 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 valh ys is at once aji- 

 jiarent. The mountain valleys are flat or rolling country, from :!,(HHI to ."i.OOd 

 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 jteaks, 

 steep slopes and deep .steep-sided canyons. They begin at from .'^,000 to 5.0f)0 

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



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

 ern prairie region in Carljon and Sweet Grass counties, westward to the \vestern 

 border of the state, and northward to include western Jleagher and Broadwater 

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

 smaller areas i.solated 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. 

 Wliether it sliould be extended to include Granite and Ravalli counties is uncer- 

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

 the soutliern 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 narrovv- sti'ii-i of country west 

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

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

 is characterized by lack of the soi;thern and western forms of tlie other moun- 

 lain regions, and by the breeding in small numbers of such northei'n species as 



