2025-06-30_PERMIT FILE - C1981019

• Permit No: C1981019
• IBM Index Class Name: Permit File
• Doc Date: 6/30/2025
• Section_Exhibit Name: 2.04 Information on Environmental Resources
• Media Type: D
• Archive: No

RULE 2 PERMITS

Rule 2 Permits 2.04-64 Revision Date: 6/4/25
Revision No.: MR-264
other transects, these were trapped for three consecutive nights in the spring of 1976. These
transects were conducted to collect data on small mammal response to the removal of cover in the
habitat improvement areas.

The rodent trapping grids were sampled during the fall of 1975 and spring of 1976. For the fall of
1975, grid 1 (in sage-grass habitat type) averaged 36.7 rodents/acre, 99% of which were deer mice.
Grid 2 (in sage grass -serviceberry habitat type) was in poor condition (shrubs were sprayed in the
past to improve grazing) and produced an average of 25 rodents per acre on grid 2, 96+% of the
rodents captured were deer mice. During the spring of 1976, grid l produced an average of 25.4
rodents/acre, and grid 2 produced an average of 20 rodents/acre. Trapping success for grids l and
2 were 30% and 23%, respectively.

Total numbers of rodents captured and density per acre were higher in the fall than in the spring.
This is a function of post-reproduction versus pre-reproduction numbers.

Data from the trapping transects located adjacent to the browse transects was collected only to
determine rodent species diversity within the habitat types. Table 2.04.11-9, Rodent
Species/Habitat Type, shows the habitat types and the species captured.

The U.S. Fish and Wildlife Service also conducted a nine day small mammal sampling program
in 1975. Five traps were used on a 5-acre grid in a mark-recapture effort for six days. After the 6th
day, a transect line (20 stations, 3 traps per station) was used to sample the area for three days and
nights. Results of the small mammal sampling are shown in Table 2.04.11-10, USFWS - Small
Mammal Transects. Additional information concerning the USFWS sampling program is found in
Exhibit 11, Wildlife Information.

Data collected for 1975 and 1976 show that, (1) rodent densities on the site were high compared
to those of other areas of the west; (2) total numbers of rodents were affected by condition of the
habitat; (3) habitat type also affected the diversity and numbers of rodents; and d(4) rodents were
not drastically affected by cover removal of the habitat improvement areas.

Lagomorphs

When the pre-mining wildlife studies began in 1974, Lagomorph numbers were extremely low.
The CPW estimated jackrabbit densities at 4.0 animals/square mile and cottontail densities at about
10.0 animals/square mile in 1974. Observations from 1974-1979 showed a stead increase in
numbers with a peak probably occurring in 1979. Cyclic population fluctuations of these two
species is a common occurrence which makes it difficult to accurately estimate numbers.

Relative abundance, presence, and probably habitat of Lagomorphs are set forth in Table 2.04.11-
11, Wildlife Species that Occur or are Likely to Occur in the Colowyo Permit Area.

Avifauna