Yellow-bellied marmot Marmota flaviventris Distribution. Western North America: US Rockies, Sierra Nevada and intermountain west. Yellow-bellied marmots are the best studied marmot species. Dr. Kenneth B. Armitage and a number of his students have studied a population in Gothic, Colorado since 1962. Yellow-bellied marmots have a harem-polygynous social system whereby a male defends and mates ...