Known for its paddle-shaped tail and friendly, toothy face, the beaver is a living, gnawing symbol of Canada's industrious spirit.

But don't be fooled by the cute and furry appearance.The big rodents can be dam ferocious.

Beaver attacks are on the rise in Edmonton. In the past month, several people have reported that their dogs have been attacked at the Terwillegar off-leash park.

Some pets have suffered serious injuries, and people are being encouraged to keep their dogs out of the water.

The city has installed two temporary signs and two permanent billboards warning pet owners of the risk. Some treed areas have been fenced off so dogs don't go into the bushes.

Beavers are strong and can be aggressive, said Bill Abercrombie, a trapper and wildlife expert based in Sherwood Park.

"An adult beaver can easily weigh 30 kilograms. The teeth that they have are very sharp, they're just like a set of chisels," Abercrombie in an interview Friday with CBC Radio's Edmonton AM.

"Their jaws are obviously very strong because they cut down trees with those jaws and they won't hesitate to attack.

Bill Abercrombie, a hunter and trapper based in Sherwood Park, says beavers become more aggressive in spring when their young are leaving the lodge. (Bushman Inc.) "A dog swimming in the water at the wrong time could come under attack and attacks can be very serious."

Beavers have been known to clamp on to dogs, biting and clawing at them when they wade into the brackish pond that skirts the Terwillegar dog park.

They're aggressive, they are certainly aggressive with each other, and certainly aggressive with canines," Abercrombie said.

"Particularly in the spring, beavers are very much in territorial mode and protective mode because the young beavers are out and about in June. This is when they're weaned and they're vulnerable."

Abercrombie said aggressive beavers are attempting to protect their young from predators.

Dogs swimming in the water, especially if they're sniffing around a beaver lodge, could be vulnerable to attack.

Just about every predator regards beaver as a delicacy so they're under intense pressure. -Bill Abercrombie , Bushman Inc.

Beavers will spook easily when they're out of the water, he said.

"Just about every predator regards beaver as a delicacy so they're under intense pressure from a lot of predators, whether it's wolves, beavers, mountain lions, river otters," said Abercrombie, president and founder of Bushman Inc., an outfitting company.

"Even large birds of prey will try to pick off young beavers, so there is an added stress with the adult beavers and they have very low tolerance for canines."

Abercrombie said owners looking to protect their pets should watch carefully for signs of beavers, and respect their habitat. Chewed-off tree trunks, wood shavings and beaver lodges are all telltale signs that beavers are on the move in the area.

"Dogs that come into close proximity, whether they're on a leash or not, are going to get it," Abercrombie said.

"It's part of that conflict between humans and human pets and the wild animals."