| Siskiyou chipmunks have their own, distinct vocalization: a long, intense, one-syllable call that starts low, rises, and then falls again. It starts at a frequency of about 300 kHz, rises to more than 1,600 kHz, then falls to about 400 kHz. They are among the larger chipmunks, with relatively dull brownish or grayish coats, and are usually found in moist coniferous forests dominated by Douglas-fir. Siskiyou chipmunks have one litter of 4-6 young annually, in June.
Howell, A.H., 1922. Journal of Mammalogy, 3:180.
Mammal Species of the World