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• By February, populations are entirely comprised of adult mice and by June, a <br />substantial fraction of the population is immature (juvenile or subadult). <br />This porportion of adults to juveniles will remain high as summer progresses. <br />The upland sagebrush stands, which lacked diversification within the vegeta- <br />tive community, showed exceedingly poor diversity of [rappable mammals. Deer <br />mice were the only small malmnals captured in this community (Table E-1). The <br />higher location on Williams Fork Mountain generally exhibited the greatest <br />[rappable mammalian diversity as well as highest abundance (Table E-1). This <br />site is a typical mountain shrub community possessing dense coverage of oak <br />and serviceberry interspersed with small grassy openings which contained scat- <br />tered sagebrush and chokecherry plants. <br />Figures E-2 and E-3 illustrate the abundance of small mammals at the Williams <br />Fork Mountains trapping locations relative to [he abundance of the deer mouse. <br />Absolute determinations of abundance are difficult to obtain for small mammals <br />• and relative abundance comparisons are generally employed to characterize <br />fluctuations in numbers over time. In this region where the deer mouse <br />appears as the most conspicuous mammal in [he trapping data through all sea- <br />sons of [he year, i[ is logical to concentrate attention on this species. In <br />formulating comparisons, i[ is crucial to recognize [h a[ small marmaals common- <br />ly demonstrate dramatic fluctuations in population Level over a period of <br />years. <br />2. Medium-sized Mammals <br />The inventory for medium-sized mammals is based on Ecology Consultants, Inc.'s <br />studies and observations and the direct observation of animals, tracks, scats, <br />and identifiable remains by Trapper Mine personnel. <br />A [rack census of watering areas within the proposed mine plan area was con- <br />ducted June 2, 1980. Muddy banks of ponds, edges of seeps, and springs were <br />surveyed by walking clockwise around [he water edge and then re-checked by <br />. walking counterclockwise around the same area. The results of [he census are <br />listed in Table E-2. Location of census sites are shown on Map M19. <br />E-23 <br />