Introduction 



Birders in Montana have recorded the presence of 357 species over the past four 

 decades. There are 259 species that regularly breed in the state. The total number 

 of wintering species is 177. An additional 12 species are of hypothetical occurrence 

 (see p. 112), including several species that are expanding their ranges and will likely 

 make their way into a future edition of the Montana Bird Distribution. 



Physiography of Montana 



Montana is characterized by 3 physiographic divisions: the Rocky Mountains of the 

 western third, dominated by high rugged mountain ranges dissected with broad 

 valleys; the central plains where island mountain ranges rise out of the grassy plains; 

 and the eastern half in the Northern Great Plains with rolling grass-covered plains 

 carved by major rivers. 



Vastly different climate and vegetation occur in Montana. Continental air masses with 

 cold, dry winters and hot summers dominate most of the state. Northwest Montana is 

 more influenced by Pacific moist air with moderate temperatures. The plains range 

 between -40°F(-40°C) and over 1 00°F (38°C), with annual precipitation between 8 inches 

 (20 cm) and 15 inches (40 cm). Droughts can be frequent and severe. The Rocky 

 Mountains are somewhat cooler and more moist. Annual precipitation generally 

 increases with elevation, much of it as snow. 



These factors, combined with Montana's geographic position among the Great Basin, 

 Great Plains, and Northern Rockies, contribute to the great diversity and abundance 

 of birds in our state. Land-use practices have also changed the abundance and 

 distribution of our avifauna. Some species (such as the starling) tend to thrive in 

 human-altered landscapes, expanding their range and numbers. Other species (such 

 as the piping plover) require specialized natural habitat and may become increasingly 

 rare or threatened by habitat changes or encroachment of competitors. 



As we view the distribution of Montana birds over time, we will undoubtedly witness 

 the introduction and expansion of some species and the continued decline of others, 

 particularly those that are more specialized. Montana is a large, sparsely-populated 

 state. It is difficult to conceive of high-intensity efforts to atlas birds as in other states. 

 Until the financial and human resources become available, the application of coarse- 

 scale distribution units such as latilongs will continue to be the most feasible. By 

 refining our efforts to the quarter latilong, we will be recording the dynamic phenomena 

 of statewide bird distribution to the best of our current abilities. As additional data are 

 recorded by quarter latilong, we expect this effort to more effectively project species' 

 distribution. 



Latilongs as Mapping Units 



Latilongs are rectangular units formed by successive parallels of latitude and 

 meridians of longitude, each at one degree intervals (see map on back cover). They 

 form a grid pattern across Montana that includes all or parts of 49 latilongs. The 

 average dimensions of each latilong are 47 miles (76 km) wide and 69 miles (1 1 1 km) 



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