Using satellite imagery and Google Earth software, a Canadian ecologist has discovered the world’s biggest beaver dam in a remote area of northern Alberta. The actual dam is about 850 metres (2,800 feet) long on the southern edge of Wood Buffalo National Park, and is huge by average standards. Beaver dams in Canada are 10 to 100 metres long, and only rarely do they reach 500 metres.
Construction of the dam likely started in the mid-1970s, said Jean Thie, who made his discovery quite by accident while tracking melting permafrost in Canada’s far north. Several generations of beavers worked on it and it’s still growing.
North American beavers build dams to create deep, still pools of water to protect against predators, and to float food and building materials. In this particular area, the region is flat so the beavers have had to build a massive structure to stem wetland water flows, Thie said, noting that the dam was visible in NASA satellite imagery from the 1990s.