Most visitors to City of Rocks will observe Mule Deer, Mountain Cottontail, Blacktail Jack Rabbit, Yellow-Bellied Marmot and Golden-Mantled Ground Squirrel, Northern Pocket Gopher, and Least Chipmunks.  The reserve and surrounding area is also home to a number of species that rarely occur further north in Idaho such as Pinon Mouse, Cliff Chipmunk, Ringtail, Pygmy Rabbit and Desert Bighorn Sheep. Also documented within the reserve are the more elusive Mountain Lion, Bobcat, Coyote, and Elk. All documented mammals are included in the reserve's Wildlife Checklist.

Species Spotlights:

Northern Pocket Gopher (Thomomys talpoides)

The Northern Pocket Gopher is about the size of a ground squirrel (total length 6.5 to just over 9 inches), and weighs 2.5 to 5 ounces. Like all pocket gophers, they have a tube-shaped body, very small eyes and ears, short and smooth fur that is brownish tan, and a short tail. Long front claws accommodate efficient digging and its large external, fur-lined pouches are for carrying food. There are dark patches behind their ears. This pocket gopher is the most widely distributed species in Idaho. 

The Northern Pocket Gopher prefers deep soils along streams and in meadows and cultivated fields, but is also found in rocky soils and clay, in brushy areas or along the roadside, and in alpine tundra. They are active throughout the year and do not hibernate, but may be inactive in winter and midsummer for brief periods. Their daily activity peaks at dawn and dusk. Food is often carried in cheek pouches and stored in underground chambers, or in or under snow. Pocket gophers are ecologically important in influencing soils with their burrowing activity and allowing greater moisture absorption by the soil. They may also help reduce erosion as a result of their tunneling.

Females only breed once a year. Mating usually occurs from March to mid-June, depending on weather and latitude. A female produces a litter of 4 to 7 young, after a gestation period of 19 to 20 days. The young disperse from the burrow at about 2 months old.

Mountain Lion (Felis concolor)

With sightings documented from Canada to Argentina, the Mountain Lion (also known as Puma, Cougar, and Panther) is the most widely distributed feline in North America. Although as many as three individual lions include City of Rocks in their home range, the chance of actually seeing one is unlikely, but evidence of their existence is readily available.

Tracks and scat are the most common clues to lion activity. Tracks are round with 4 distinct toe pads. No claw marks should be evident, as claws are retracted while walking. The size of the foreprint can range from 3-4" and the hindprint should be slightly smaller. Scat can range in shape and size from masses to irregular cylinders to pellets, and frequently contains traces of hair and bone scraps. Sometimes covered by earth, scat is often left partially exposed as a form of territorial scent marking. Strong, silent, solitary and territorial all accurately describe this elusive cat. Hunting by day or night, a male can cover up to 25 miles searching for prey.

 Lions preferably feed on large mammals such as mule deer. Lions also feed on coyotes, porcupines, mice, marmots, hares, raccoons, birds and even grasshoppers. Isolated incidents of mountain lions attacking humans have been documented in areas outside of City of Rocks (one documented attack in Idaho). Even when lions are encountered, they rarely pose a threat. In fact, most prefer to avoid human contact. While hiking in lion country, always be aware of your surroundings and hike with a companion.