The Ground Squirrel species is not arboreal. They cannot climb trees, but live in burrows dug with their sharp claws (longer & less curved than tree squirrel's). They must constamtly be alert for ground predators, and for those from the sky. I have not been able to find an explanation for the very large testicles of the male. This species is larger than the arboreal species, and may weigh as much as 20 lbs. [Okaukuejo, Namibia].