WSP13037

• File Number: 8280.10
• Description: CREST - Colorado River Enhancement Snowpack Test
• State: CO
• Author: Unknown - Crest members/BOR?
• Title: Briefing Document for the Colorado River Enhancement Snowpack Test
• Water Supply Pro - Doc Type: Report/Study

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effects of weather components on big game. "Section 2, Ecological,
Wildlife, and Biocommunities," of this report series states:

"Various weather components seem to influence the activities
of many big game species: 1. game species move to areas of
the most available forage; 2. game species move to areas of
the most nutritious forage; 3. relative humidity affects the
length of rest periods which are longer on more humid days
and shorter on less humid days; 4. animals rest in areas
away from wind; 5. precipitation~ unless accompanied by
wind, does not affect the activity of game species; 6. game
species use higher elevation ranges during dry summers;
7. game species are more observable during dry summers
because of lack of cover and search for preferred food
species; 8. winter snows decrease the availability of total
range, cover, and food; 9. low temperatures decrease activi-
ties,of game species; 10. winds of 15-25 mph and low tempera-
tures cause game species to feed later in the morning;
11. low temperatures and snow depth force the congregation
of animals which increases their susceptibility to predation;
12. food availability eliminates many of the weaker animals;
13. migrational movements from one range to another are
influenced by time and/or weather; 14. spring storms can
reduce the condition of animals and/or reduce the number of
individuals in a population; 15. food habits of some species
change with the amount of precipitation which can be benefi-
. cial or detrimental; and 16. use of south facing slopes for
filod and north facing slopes for protection." [16, p. 8]

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Studies of the response of small mammals to winter snow accumulation in
the San Juan Mountains [10J do not reveal clearly predictable responses.
Lower population numbers seem to occur after winters with late snowpack
and late melt. The proximate cause seems to be springtime shortage of
proper food and a shortened breeding season. Other factors, such as
changes in land use, appear to have a more direct effect on small
mammal populations. The Skywater Programmatic FES states:

. .

liOn the bas i s of the above fi nd i ngs, it is expected that the
Skywater programs of field experimentation will have no
discernible impact on small-mammal populations. The potential
impact of widespread or prolonged application of precipitation
management will probably involve occasional epiSOdes or
circumstances resulting in temporary declines in small-millnmal
populations. Because of the large population fluctuations
that normally occur, declines caused by these infrequent
episodes wil I be difficult to identify or attribute to
specific causes. There appears to be lit:;~ likelihood that
such .applications will significantly affec: the range of
diversity of small-mammal species." [2, D. 3-131j

The effect of additional precipitation on furbearers, reptiles, insects,
and birds has not been considered a controlling fac:or to the well-being
of the various species. Migratory birds would not be affec:ed by

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