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<br />12. food availability eliminates many of the weaker animals; <br /> <br />13. migrational movements from one range to another are <br />influenced by time and/or weather; 14. spring storms can <br /> <br />reduce the condition of animals and/or reduce the number of <br /> <br />individuals in a population; 15. food habits of some species <br />change with the amount of precipitation which can be benefi- <br /> <br />cial or detrimental; and 16. use of south facing slopes for <br />food and north facing slopes for protection.1I [16, p. 8] <br /> <br />Studies of the response of small mammals to winter snow accumulation in <br />the San Juan Mountains [10] do not reveal clearly predictable responses. <br />Lower population numbers seem to occur after winters with late snowpack <br /> <br />c <br /> <br />and late melt. The proximate cause seems to be sprintime shortage of <br />proper food and a shortened breeding season. Other factors, such as <br />changes in land use, appear to have a more direct effect on small <br /> <br />mammal populations. The Skywater Programmatic FES states: <br /> <br />liOn the basis of the above findings, it is expected that the <br /> <br />Skywater programs of field experimentation will have no <br />discernible impact on small-mammal populations. The potential <br />impact of widespread or prolonged application of precipitation <br /> <br />management will probably involve occasional episodes or <br />circumstances resulting in temporary declines in small-mammal <br /> <br />populations. Because of the large population fluctuations <br /> <br />that normally occur, declines caused by these infrequent <br /> <br />episodes will be difficult to identify or attribute to <br /> <br />specific causes. There appears to be little likelihood that <br /> <br />32 <br />