_Specimens examined._--Total, 35: Prater Canyon, 7600 ft.,
74408-74410 MVZ; Upper Well, Prater Canyon, 7575 ft., 69279; 1/4
mi. N Middle Well, Prater Canyon, 7500 ft., 69280; Middle Well,
Prater Canyon, 7500 ft., 69281-69285, 75977; Morfield Canyon, 7600
ft., 75978; 3/4 mi. S, 1-3/4 mi. W Park Point, 8000 ft,
69286-69288; 1-1/4 mi. S, 1-3/4 mi. W Park Point, 8000 ft., 69289;
1-1/2 mi. S, 2 mi. W Park Point, 8075 ft., 69290; Sect. 27, head of
east fork Navajo Canyon, 7900 ft, 69291-69292; 1/2 mi. N Far View
Ruins, 7825 ft, 69293; Far View Ruins, 7700 ft., 69294, MV
7852/507, 7853/507; 3 mi. N Rock Springs, 8200 ft., 69295-69298;
2-1/2 mi. N, 1/2 mi. W Rock Springs, 8100 ft., 69299-69301; 2 mi.
N, 1/4 mi. W Rock Springs, 69302-69303; 1 mi. NNW Rock Springs,
69304; 1/2 mi. NNW Rock Springs, 69305; Mesa Verde, northern end,
8100 ft., 149087 USNM.
The pocket gophers of the Mesa Verde and vicinity are of one species,
_Thomomys bottae_. The distribution and variation of this species in
Colorado have been studied recently by Youngman (1958) who referred all
specimens from the Mesa Verde to _T. b. aureus_. He noted that some
specimens have dark diffuse dorsal stripes that are wide in specimens
from the Mancos River Valley. The generally darker color of the
specimens from the Mancos Valley as compared with that of specimens from
on the Mesa was noticed in the field, and is another example of the
local variability of pocket gophers. The nine specimens listed by
Youngman (1958:372) as from "Mesa Verde National Park," Mancos River,
6200 ft., are not here listed among "specimens examined" because
possibly some, or all, of the nine were trapped on the east side of the
River and therefore outside the Park. None was, however, farther than 30
yards east of the Park.
In the Park, pocket gophers occur both on mesa tops and in canyons. Most
of the localities listed above and others at which mounds were seen are
areas of disturbance such as the old burn on Wetherill Mesa, the rights
of way for roads, the river valley, and the grazed floor of Prater
Canyon. Little evidence of pocket gophers was found on unusually rocky
slopes, steep slopes, or in stands of pinyon and juniper or in
relatively pure stands of oak-brush. In addition to workability of the
soil, the presence of herbaceous plants, many of them weedy annuals, is
probably the most important factor governing the success of pocket
gophers in a local area. No female was recorded to have contained
embryos, but two had enlarged uteri or placental scars. This fact and
the capture of nine half-grown individuals indicate breeding prior to
late August when most specimens were trapped.