The Kaibab squirrel lives in ponderosa pine forests, where it builds its nest out of twigs and pine needles. Kaibab squirrels, ponderosa pines, and the fungi which grow in the vicinity of the ponderosas exist in a symbiotic relationship. The squirrel eats acorns, fruit, and fungi (especially an underground truffle), as well as the seeds, bark, and twigs of the trees where it makes its home. The Kaibab squirrel's most significant source of food is the seeds found within ponderosa pine cones. Young squirrels are born between April and August.