1 



B = r. 2 



where P,- = proportion of species total density in habitat i 

 niche breadth values can range from 1.0 to the total number of habitats sam- 

 pled. All niche breadth values were standardized by dividing the total number 

 of habitats sampled to yield a statistic with a range of 0.0 to 1.0 for com- 

 parative use. 



Niche overlap was calculated by Pianka's (1973) formula to quantify the 

 degree to which species share habitat types: 



Oij =Oji -JiTJ^^ 



where 0-- = G-,-^ = niche overlap between species; and species 

 x]j^ = proportion of species i numbers in habitat k, 

 Xjk = proportion of species i numbers in habitat k. 



Home Range Calculation . Home range dimensions were calculated using the 

 convex polygon index (Jenerich and Turner 1969) for each animal captured three 

 or more times and for which no captures occurred on the periphery of the live- 

 trap grid. The maximum lengths of home ranges were also calculated by measuring 

 the distance between the two most distant capture points for each individual 

 captured three or more times. 



Computer Sorting . Data were sorted by computer using programs written and 

 modified from a program by Renewable Resources Consulting Services (RRCS). The 

 major portion of the population data were compiled using modified version of a 

 package developed by Krebs (1967). Home range calculations were performed by 

 a program available from the IBP at Colorado State University. 



LAGOMORPH SURVEY 



Hares and rabbits were sampled along two roadside routes, one of which was 

 18.7 km (11.6 miles) in length and located entirely within the proposed mining 

 area, the other of which was 27.5 km (17.1 miles) in length and located entirely 

 outside the proposed mining area (map 3). Methods were modified from those of 

 Flinders and Hansen (1973, 1975) and Lord (1963). 



The two routes were run consecutively on each of three days from October 21, 

 to October 29, beginning with the mining area route at 4:00 A.M. and ending be- 

 fore 6:30 A.M. The observer drove the routes at a fairly constant speed, not 

 exceeding 25 km/hr (16 mi/hr), using higli-beam headlights to locate animals. A 

 spotlight was used only when animals could not be identified by headlights alone. 

 An assistant recorded the species and location of all hares and rabbits observed. 

 No attempt was made to calculate density as described by Flinders and Hansen 

 (1973) due to small sampling size and few sampling repetitions; results were 

 intended for use only as an index for later comparisons. 



39 



