BREEDING BIRD CENSUS 



Five breeding bird census plots were established to sample bird populations w 

 of three representative habitats (grassland, sagebrush, coulee complex) in and 

 near the proposed mining area (map 3). Grassland and coulee plots were laid out 

 in pairs. Each pair consisted of one plot on, and one plot off the proposed min- 

 ing area. These plots were 25.0 ha or 500 X 500 m (61.8 acres) in size and were 

 separated by 1 km (0.6 mi) or more. The sagebrush plot, however, was 24.0 ha 

 or 800 X 300 m (59.4 acres) in size and overlapped the boundary of the proposed 

 mining area. The grids were paced using a transit or hand compass, and staked 

 at 100 m (328 feet) intervals using wooden lath. Corners were permanently marked 

 with steel posts or, where a fence intersected the plot, with red spray paint. A 

 census was taken of each plot eight times during the period April 28 through 

 August 17, 1977 using standard territory-mapping methods (Hall 1964, Rough 1947, 

 Robbins 1970, Van Velzen 1972). The percentage of habitat composition of the 

 five census plots is shown in table 5, and the census schedule is shown in 

 Appendix F. Biomass estimates were based on published accounts of bird weights 

 (Baldwin and Kendeigh 1938, Poole 1938, Stewart 1937, Wiens 1973), specimens 

 taken during this study^and Montana-taken specimens housed at the University of 

 Montana, Montana State University, and Conner Memorial museums. 



INSECT STUDIES 



During the summer field season it became apparent that grasshoppers exert a 

 significant influence on grassland ecosystems, and may in fact be the predominant 

 herbivore in certain vegetation types. Work on pollinating insect study design 

 was therefore deferred in favor of a plan of study to sample grasshopper popu- ^ 

 lations. Preliminary plans were made to sample grasshopper density, biomass, age 

 structure, and diversity in various vegetation types several times during the sum- 

 mer. The possibility of using nets, pitfalls, or vacuum sampling techniques was 

 investigated. However, progress on insect studies was terminated upon notifi- 

 cation of the decision by Dreyer Brother's, Inc. to delay initiation of further 

 studies. 



SMALL MAMMAL STUDIES 



Live Trapping 



Two pairs of live-trapping grids were established to sample small mammal 

 populations in each of the representative grassland and sagebrush habitats in 

 and near the proposed mining area (map 3). Each pair consisted of an experimental 

 plot on the proposed mining area, and a control plot off the proposed mining area. 

 Each of the four plots consisted of 100 trap stations in ten rows of ten spaced 

 at 15 m (49 ft) intervals. Plots were surveyed using transit and chain, and all 

 stations were marked with wire surveyors' flags. One Sherman live trap 10 X 7.5 

 X 23 cm(or 3.9 X 3.0 X 9.1 inches) was placed at each station during trapping 

 periods. Traps were baited with peanut butter and rolled oats and furnished . 

 with synthetic cotton for nesting material at the beginning of each trapping 

 period and whenever necessary during the trapping period. All grids were trap- 

 ped for three consecutive days in April and again for four consecutive days each 

 month from June through October. Each live-captured animal was numbered by toe g^ 



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