Rhinopithecus roxellana is a largely arboreal species. The diet varies according to the season. During the warm weather months, R. roxellana feeds primarily on leaves from broad-leaf trees and fir and pine needles. Buds, bark, and fruit seeds provide supplementary nutrition. During the winter, however, these monkeys switch to a more limited diet of bark and lichen. Although the species feeds largely from arboreal sources, it will descend to the ground to feed on grasses and wild onions.

(Emanoil, 1994; Kirkpatrick, 1995; Schaller, 1985)

Plant Foods: leaves; wood, bark, or stems; seeds, grains, and nuts; lichens

Primary Diet: herbivore (Folivore , Lignivore)