12 PACIFIC COAST AVIFAUNA No. 14 



the Bohemian Waxwing and Iludsonian Chickadee. The Montana J unco I'cplaees 

 the Pink-sided as it does in the northwestern region. 



The northwestern monntain region includes the rest of the state. It lies 

 entirely west of the continental divide, from the western boundaries of the north- 

 eastern mountain region and the northern boundaries of the southern mountain 

 region, westward and northward to the limits of the state. It miglit readily he 

 termed the humid mountain region, for it is much more humid i7i climate than 

 any other part of the state. It is characterized by a good many species and sub- 

 species, such as Townsend Warbler, Chestnut-backed Chickadee, Varied Thrush, 

 Merrill Song Sparrow^ and Dusky Horned Lark. It really forms part of a re- 

 gion which includes northern Idaho and northeastern Washington, a region 

 where the rainfall is considerably greater than in surrounding areas both east- 

 ward and westward, and where many Pacific Coast species find their eastei-n 

 limits. A more detailed study of the region, with a greater amount of collecting, 

 ought to bring out many interesting points and probably show some new sub- 

 species. 



The life-zones found in iMontana are the Upper Sonoran, Transition, Cana- 

 dian, Iludsonian and Alpine-Arctic. These zones cross the faunal areas, their 

 boundaries being mainly at right angles to the mountain slopes. The Upper So- 

 noran occupies the areas of lowest elevation, and the Alpine-Arctic those of high- 

 est. Since these zones are better characterized by their vegetation, particularly 

 their trees, than by their birds, I shall give the species of trees which character- 

 ize them in IMontana, to serve as an aid to others in studying this phase of dis- 

 tribution. 



The Upper Sonoran zone occupies the lower valleys of the state, mainly the 

 areas below 4,000 feet in elevation east of the continental divide, and those below 

 3,000 feet west of it. It occupies nearly all of the southern prairie region, and 

 extends in long narrow strips along the rivers to the westward. While the 

 map of life-zones accompanying the 1910 A. O. U. Check-List shows this zone 

 only in the southern prairie region, I am inclined, after a study of Cary 's (1917 i 

 recent paper on Wyoming life-zones, to think that this zone also occupies certain 

 of the valleys in the mountain region which are of low elevation. If such species 

 as the ]\Iourning Dove, Bullock Oriole, Arkansas Kingbird, Lazuli Bunting and 

 (-atbird are characteristic of the Upper Sonoran in IMontana, as they an^ in 

 Wyoming, then there must be many areas of upper Sonoran witliin the moun- 

 tains. I believe that th(^ IMissouri Valley in Broadwater County, and areas along 

 the IMissouri as far south as Three Forks and perhaps up the Jefferson and Madi- 

 son, should be considered Upper Sonoran. I believe this is also true of areas 

 west of the continental divide, up the Hell Gate River at least as far as IMissoula, 

 and on the Pend-Oreille nearly to Poison, and perha])s above Flathc^ad Lake 

 about Kalispcll. However, it seems fjuite certain that the species last named 

 above breed locally in the Transition. As in Wyoming, it is true that the line 

 between these two zones is indefinite and difficult to draw. Tl'erc are no very 

 characteristic trees in this zone. Junipers and cedars, which are characteristic 

 in other regions, nrc scarce, and grow quite as abundantly in the Transition as 

 in this zone. Cottonwoods are the commonest trees, but are also common in the 



