- Kaibab Squirrel gives us one nice example of the evolution that is caused by geographical isolation - about 10,000 years ago when the last Ice Age ended, physical formations in the valley changed in a way that prevented squirrels from reaching the Colorado River. The valley has become a geographical barrier separating forests and squirrels on each edge. One group of squirrels became two separate groups that were no longer able to mate, kaibab squirrels. Abert squirrels are North American species, found across a group of locations. Kaibab squirrels are a subspecies of Abert squirrels, found only in one region in the United States. - Kaibab and Abert squirrel live in ponderosa pine forests, where they build nests of twigs and pine needles. They eat nuts, fruits, and fungi, as well as seeds, bark and twigs from the trees they make at home. The most important source of food in the squirrel Kaibab is the seeds contained in the cones of ponderosa
