July 12, 2012; Petrified Tree, Yellowstone National Park.

From Wikipedia:
The least chipmunk (Neotamias minimus) is the smallest chipmunk in North America. It is also the most widespread species of chipmunk in North America occurring across north-central and western United States and from British Columbia and southern Yukon to western Quebec in Canada. The species is found in a variety of habitats including mixed deciduous and coniferous forests, boreal forest, and sagebrush plains.
They have three dark lines with white in between along their face and five black stripes with brown edges and white in between along their back. They are grey and reddish-brown on the sides and greyish white on their underparts. Their tail is orange-brown.
These animals are active during the day and eat seeds, berries, nuts, fruits and insects. Predators include hawks, owls and mustelids.
They breed in early spring. Females produce one litter usually of 5 or 6 young.
They store food in an underground burrow, where they spend the winter. These animals go into a state of torpor for extended periods of time, but do not hibernate.