Dam!

A friend and reader forwarded this story to our attention this morning. Thanks David!

World’s biggest beaver dam discovered in northern Canada

by Michel Comte and Jacques Lemieux – Wed May 5, 7:46 pm ET for Yahoo News

OTTAWA (AFP) – A Canadian ecologist has discovered the world’s largest beaver dam in a remote area of northern Alberta, an animal-made structure so large it is visible from space.

Researcher Jean Thie said Wednesday he used satellite imagery and Google Earth software to locate the dam, which is about 850 metres (2,800 feet) long on the southern edge of Wood Buffalo National Park.

Average beaver dams in Canada are 10 to 100 metres long, and only rarely do they reach 500 metres.

First discovered in October 2007, the gigantic dam is located in a virtually inaccessible part of the park south of Lac Claire, about 190 kilometres (120 miles) northeast of Fort McMurray.

Construction of the dam likely started in the mid-1970s, said 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,” he told AFP in Ottawa.

Mike Keizer, spokesman for the park, said rangers flew over the heavily forested marshlands last year to try to “have a look.” They found significant vegetation growing on the dam itself, suggesting it’s very old, he said.

“A new dam would have a lot of fresh sticks,” Keizer explained. “This one has grasses growing on it and it’s very green.”

Part of the dam may have been created by naturally felled trees, and the beavers “opportunistically filled in the gaps.”

Thie said he recently identified two smaller dams sprouting at either side of the main dam. In 10 years, all three structures could merge into a mega-dam measuring just short of a kilometer in length, he said.

The region is flat, so the beavers would 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.

“It’s a unique phenomenon,” he said. “Beaver dams are among the few animal-made structures visible from space.”

North American beavers build dams to create deep, still pools of water to protect against predators, and to float food and building materials.

A 652-meter structure in Three Forks in the US state of Montana previously held the record for world’s largest beaver dam.

Thie said he also found evidence that beavers were repopulating old habitats after being hunted extensively for pelts in past centuries.

“They’re invading their old territories in a remarkable way in Canada,” he said. “I found huge dams throughout Canada, and beaver colonies with up to 100 of them in a square kilometer.”

“They’re re-engineering the landscape,” he said.

We did some of our own research and we’ve found the first couple internet transcripts from 2006 of Jean Thie announcing his discovery.  There are a few .kmz files that you can click to travel to Jean’s various discovery via Google Earth (very cool). However, while we can’t claim to be beaver dam experts, it’s rather difficult, even with the resolution of Google earth to pick out what exactly might be the dam and not just Canadian wilderness. But we’re happy to give Jean the benefit of the doubt here. Oddly enough this is our first beaver dam story on Animal Architecture…who knew?