This dataset focuses on monitoring beaver colonies in Forillon National Park. Beavers have a major influence on aquatic ecosystems in the park. Monitoring fluctuations in this population can help us better understand variations in the physicochemical characteristics of watercourses and possibly in other aquatic populations in the park. Beaver colony data are collected primarily as part of a park-wide aerial survey by helicopter. Beaver colony inventories were conducted in 1980, 1991, 1996 and 2010. The presence of food piles, dams, lodges and signs of fresh cuts is considered during helicopter flights to determine whether or not the colony is active. Beaver colony inventories take place in the fall and are planned for every ten years.