Big Sagebrush and Big Sagebrush/Grassland 



While no census plots were located in this habitat, the roadside counts 

 revealed a low diversity and abundance of birds. Small mammal 

 biomass was relatively low to average (table 37). Characteristic species 

 include: 



Yearlong Residents : sage grouse*, desert cottontail. 



Summer Residents : sage thrasher*, vesper sparrow*, lark sparrow. Brewer's 

 sparrow*. 



Silver Sagebrush and Silver Sagebrush-Grassland 



A breeding bird census plot located in this habitat showed the highest 

 species number and total density of all habitats sampled; biomass and species 

 diversity were high but not as high as the coulee plots. Small mammal traplines 

 revealed variable species diversity and moderate to high biomass, while live- 

 trapping grids showed wery high late-summer small mammal biomass. Characteristic 

 species include: 



Yearlong Residents : 

 harvest mouse. 



sharp-tailed grouse, sage grouse, deer mouse, western 



Summer Residents : western meadowlark, lark bunting. Brewer's sparrow. 



Vesper sparrows were much rarer than in big sagebrush-dominated habitats. 

 Brewer's sparrows were more common than reported by Swenson (1978), and attained 

 densities similar to those obtained by Best (1972) and Feist (1968). Where this 

 type occurs as low coulee shrub, species composition is similar. 



Grassland ( Including Saltgrass, Little Bluestem, and Western Wheatgrass ) 



Grassland habitats, including several distinct community types, were the most 

 extensive habitats in the mine study area. Bird and mammal study plots and trap- 

 lines showed relatively low to moderate diversity and density. Bird diversity and 

 density were exceptionally low on a western wheatgrass plot which was nearly grazed 

 barren by grasshoppers. Characteristic species include: 



Yearlong Residents : horned lark*, deer mouse, pronghorn. 



Summer Residents : burrowing owl*, western meadowlark, lark bunting, savannah 

 sparrow, grasshopper sparrow, McCown's longspur*, chestnut-collared longspur*. 



Winter Residents : common redpoll, lapland longspur. 



Horned larks and chestnut-collared longspurs were most common on heavily grazed 

 rolling upland grassland, as found by Owens and Myers (1973) in Alberta; western 

 meadowlarks and lark buntings were most common where scattered low shrubs (especially 

 silver sagebrush) occurred. Savannah sparrows were only found in relatively lush, 

 moist bottomland grasslands. 



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