Most round-tailed ground squirrels are very small.

Spermophilus tereticaudus(round-tailed ground squirrel)

The park hosts several native mammals, including: Beaver, Cottontail rabbit, Round-tailed ground squirrel and Botta's pocket gopher.

Coyotes, round-tailed ground squirrels, collared peccaries, mule deer, white-tailed deer, and jackrabbits all eat mesquite pods, as do livestock when they are available.

The round-tailed ground squirrel (Xerospermophilus tereticaudus), known as "Ardillón cola redonda" in Spanish, live in the desert of the Southwestern United States and Northern Mexico.

Within the genus, the Mohave ground squirrel and the round-tailed ground squirrel were thought to be close relatives, sometimes a subgenus Xerospermophilus, while the spotted ground squirrel and the Perote ground squirrel were placed in the subgenus (now a genus) Ictidomys.

A few of these species are: Johnston's rockcress, Casey's June beetle, Coachella Valley round-tailed ground squirrel, Munz's mariposa lily, Pratt's dark aurora blue butterfly, San Jacinto bush snapdragon, Santa Rosa Mountain linanthus, Tahquitz ivesia, and Ziegler's aster.

"We got a glorious patch of desert that is also home to the round-tailed ground squirrel, another candidate for the endangered species list, the flat-tailed horned lizard, burrowing owls, raptures of all kinds, unique flowering plants, including some already listed as endangered, and half a dozen kinds of large insects that are endemic to the valley."

The round-tailed ground squirrel (Xerospermophilus tereticaudus), known as "Ardillón cola redonda" in Spanish, live in the desert of the Southwestern United States and Northern Mexico.