Yes you can hunt ground squirrels. They are considered rodents (varmint) from everything I've read and done. Squirrels as it pertains to the regs is "tree squirrels". Blast away my friend!!!
Chapter 6. Nongame Animals
§472. General Provisions.
Except as otherwise provided in Sections 478 and 485 and subsections (a) through (d) below, nongame birds and mammals may not be taken.
•(a) The following nongame birds and mammals may be taken at any time of the year and in any number except as prohibited in Chapter 6: English sparrow, starling, coyote, weasels, skunks, opossum, moles and rodents (excluding tree and flying squirrels, and those listed as furbearers, endangered or threatened species).
•(b) Fallow, sambar, sika, and axis deer may be taken only concurrently with the general deer season.
•(c) Aoudad, mouflon, tahr, and feral goats may be taken all year.