Deer and rabbits inhabit the trapping area. Bobcats have been seen, by myself and by others, near Rock Springs. Lizards of the genera Cnemidophorus and Sceloporus, as well as gopher snakes were seen in this area.
Three pairs of traplines were run from August 7-9, 1962, in a juniper-pinyon-bitterbrush stand on the southern end of Wetherill Mesa, starting 200 yards southwest of Double House ([Fig. 1]).
The forest on the southern end of the mesas consists of widely-spaced trees, which reflect the low amounts of precipitation at these lower elevations. Juniper trees are more numerous than pinyons, and both species are stunted in comparison to trees farther north on the mesa. Purshia tridentata (bitterbrush) is the understory codominant. Artemisia nova (black sagebrush) is present and grasses are the most abundant plants in the ground cover. Herbaceous species in the sparse ground cover include the following:
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Opuntia polyacantha Solidago petradoria Lathyrus pauciflorus Penstemon linarioides Lupinus caudatus Yucca baccata Phlox hoodii |
Only P. maniculatus was caught in this stand; all mice were caught in the first night of trapping.
Five areas were selected for trapping in the summers of 1963 or 1964, in order to test hypotheses concerning habitat preferences of each of the species of Peromyscus. Four of these areas appeared to be ideal habitat for one species, but not for the other. The fifth area was expected to produce both species of Peromyscus. Each of these areas is discussed below.
One Mile Southeast of Park's Entrance
A small stand of Artemisia tridentata, occurring one mile southeast of the entrance to the park, is bordered to the north and northeast by a grassy meadow, discussed in the following account. Kangaroo rats have been reported in this general area, and I wanted to determine whether P. maniculatus and Dipodomys occurred together there. Fifty trap nights in this sagebrush, on June 20, 1963, yielded only P. maniculatus ([Table 1]).