Which National Park Is Home to the World's Largest Beaver Dam?

Editor's note: In an effort to better understand how other countries are managing their parklands, and to compare and contrast U.S. efforts to those from abroad, Traveler on occasion runs items from beyond U.S. borders.

Not so many decades ago, the beaver population in North America was in decline, thanks largely to the fur trade. Beaver numbers are on the rebound, and the animals can be found in a number of national parks. Do you know which park can claim it's home to the world's largest beaver dam?

A clue is found in the first sentence of this story, because the answer is a park in North America… but not the U.S. A.

Wood Buffalo National Park, in northern Alberta, is the largest Canadian national park, and according to Parks Canada, the second largest protected area in the world.

Most American's have a difficult time visualizing 44,807 square kilometers—the size of this park—so here's some perspective: that's an area larger than the country of Swizerland. Wood Buffalo is a place of plenty of superlatives: it's home to the largest land mammal native to North America (a herd of 5,000 Wood Bison), one of the largest inland fresh water delta ecosystems on the planet, and the place where new whooping cranes are born each year.

Thanks to a sharp-eyed researcher studying aerial photos, the park can also claim the largest beaver dam in the world.

The dam is large enough that it's visible from space; it was spotted in 2007 by Jean Thie, an environmental scientist who was using Google Earth to study environmental change in Canada's Boreal and Sub arctic Ecoregions.

Based on aerial reconnaissance and further analysis of additional photos, the beaver dam is believed to be about 850 meters long or about 2,790 feet, which is roughly the length of nine football fields. A more typical beaver dam is under 100 meters long, although this part of Canada also holds other dams ranging in length from 300 to 500 meters.

According to information posted on the website for Thie's company, EcoInformatics International, the beaver dam was discovered by "flying over the earth" with Google Earth. "It is unlikely that this dam would have been discovered without Google Earth and its high resolution image data base, in this case provided by Digital Globe."

Scientists are yet to see the impressive structure except from the air, and the area is so remote, park officials weren't even aware of its existence before Thie's photo discovery. The area is too heavily wooded to allow aircraft to land, and the area where the dam is located doesn't even have any trails, much less roads. According to a park spokesman, it would take several days of paddling and serious bushwhacking to reach the site.

Even though the dam is visible on NASA LandSat photos taken in 1990, it's not exactly obvious to the untrained eye. Apparently the work of at least several generations of beavers, the dam itself is covered with vegetation. "It doesn't look like much," park spokesperson Mike Keizer said. "It looks like a bog against a dense forest."

The terrain may be one reason for the dam's unusual length—the area is rather flat, so the animals couldn't simply tie into opposite sides of a narrow river channel, and it takes a lengthy structure to impound the amount of water desired by the animals.

The big dam apparently resulted from the connection of two smaller dams, and the growth of the impressive natural structure may not be over. Aerial photos show new beaver dams are being built nearby which could ultimately join the main dam and increase the overall length by another 50-100 meters in the next decade.

Parks Canada staff described the area the beavers have chosen as "incredibly remote and undisturbed. It is positioned in prime wetlands between the Birch Mountain highlands and the Peace Athabasca Delta. The run-off from the highlands provides the beavers with lots of water and the dense boreal forest provides them with plenty of food and wood to build the dam and lodges."

A visit to this impressive beaver dam isn't likely to be on your schedule, but if you're interested in a trip to other parts of Wood Buffalo National Park, some sections of the park are accessible by vehicle. The park website includes information to help you plan a trip.

Jean Thie, the scientist who first spotted the beaver dam, is President of EcoInformatics International Inc, a Consulting Company "specializing in strategy mapping, knowledge management and decision support systems for science and natural resource management organizations." If you're interested in more details about the beaver dam, you'll find them on his company's website.