Mountain beavers (Aplodontia rufa) are considered the most primitive living rodent species and have changed little since their appearance in the late Oligocene. Seven subspecies are recognized, with the Sierra Nevada mountain beaver (Aplodontia rufa californica) occupying the Sierra Nevada and southern Cascade geographic regions. The California Tahoe Conservancy conducted surveys on Conservancy parcels in the Tahoe Basin to document and monitor the distribution of Sierra Nevada mountain beavers. Trail camera deployments used to monitor den occupancy reveal patterns in activity and potential seasonal shifts in foraging behavior. Sierra Nevada mountain beaver burrows were regularly used by other wildlife, including rodents, lagomorphs, and carnivores.