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Henry Mountains. LaSal swaraer ranges preduced 2,149 kg/ha fresh weight <br />of available forage while similar ranges on [tie henrys produced only <br />1,314 kg/ha. forbs account fur 52% of the forage on LaSal summer <br />ranges, but only 12% of the forage on ran€es cf comparable elevation on <br />tl~e Henrys. Tl~e data suggest that the characteristics of the forage <br />found on the summer range, especially the quantity and quality of forbs <br />ex•~rt important influences on productivity of these herds. <br />The important point ill~.strated by this study is that forbs are a significant Eactor <br />in tl~e diets of does and fauns on s~rs¢er ranges. Secondly, the quality and quantity <br />of sunener range were the major influences on doe-faun counts in the study areas. <br />:~~ditionally, Wallr,.o et al. 01977) compiled data that suggests when nature ani~¢als do <br />not gain adequate weight in the sums;ier season they are Less likely to survive on a <br />winter diet dominated b}• shrubs. <br />A mule deer diet study based on observational data was conducted by Carpenter, et al. <br />(1979) in north central Colorado. These investigators found the following: <br />"During a 30-day grazing trial, six mule deer (Odocoileus <br />hemionus hemionus) at pasture altered their food selection <br />significantly as availability of forage changed. At the begin:iing <br />• of the trial when forbs and grasses were abundant, they comprised <br />better than 50% of the diet, but by the end of the trial when <br />these preferred forages were less abundant, grass and forb <br />declined. Shrub use increased and forb and grass use decreased <br />as snow depths increased. Results support the conjecture that big <br />sagebrush (Artemsia tridentata wyomingensis) in excess of 30% in <br />the diet is detrimenl-al [o mule deer nutritional health." <br />The above study was conducted between January 19th and February 17th, 1972, on big <br />sagebrush winter range. Figure 1 shows the percent of total diet contributed by each <br />species of forage over the 30-day period. Figure 2 compares the percent of each life- <br />form consumed as snow depths increased. <br />The quality of the summer diet is apparently a major factor in the survival of mule <br />deer adults and fawns over the winter. 1lorrover, in the studies cited, the preferred <br />-5- <br />• <br />