By Mark Hume, with Photography by Nick Didlick

On the pristine lakes of British Columbia, where the call of the loon has long been equated with the tranquility of wilderness, a curious shift in the balance of nature is taking place.

Common loons, the birds that grace both the back of the $20 bill and the $1 coin (known unofficially in Canada as the Loonie) have evolved a whole new attitude about people.

Trout fishermen say they are no longer safe from the attacks of the big black and white birds, which swoop around them, stealing fish right off the end of their lines.

"There are hundreds of stories out there," said Rob Oram, owner of the Tunkwa Lake Resort, whose world famous fishing lake, southwest of Kamloops, is patrolled by three pairs of aggressive loons.

Mr. Oram said he's heard of fishing tackle being broken, and at least one fisherman was bitten recently, when a loon snapped a trout right out of his hands.

"He didn't see it coming. He was just releasing the trout over the side, he had his hands in the water holding the trout, and the loon came in an grabbed it. It got his hand by mistake," said Mr. Oram.

"Another guy had a Sage fly rod worth about $400. The loon came right in beside the boat, and took the fish while it was still on the line. It dove so hard it drove the rod down on the boat and broke it."

Mr. Oram said one fisherman reported losing six of the ten fish he hooked one afternoon, to attacks from loons.

He said the birds are so alert to the behavior of fishermen they will move in on a boat as soon as they see any sign of a fish being hooked.

"If they see the net come out they are there in a minute," he said. "If they hear the reel singing (as a trout is being played) they come just like it's a call."

Mr. Oram said in the clear water it's possible to see loons darting under your boat as they chase a hooked trout.

"They move! Boy, they can swim," he said. "And they are big. I mean, really big." Neil Abbott, of Logan Lake Fly Shop, said customers are increasingly telling stories about brushes with loons.

"There are several lakes here, where if you see a loon, you know you're going to have trouble. "They'll take a fish while it's still on your line, or they'll wait until you just release it, and get it right next to the boat.

"If you release a trout that's even slightly injured - that's it, the loon has got it." Mr. Abbott said he first heard about the aggressive loon behavior in 1994, on one lake. But now it seems to be common on all lakes with loons.

Mr. Oram agreed. "You will find this on any lake in the B.C. Interior now," he said. "I don't know what's going on, but they all seem to be on the same education program. I know they are teaching it to their babies, because in the spring they come along with their parents and see what's going on."

Mr. Abbott said fishermen are fighting back by growling at loons, trying to make sounds like eagles (which prey on young loons) or fooling the birds by making splashing sounds.

"If you see a loon going after a guy with a fish you can rip some line off your reel and then splash your hand in the water. They'll come right after you. But they do seem to get pretty mad when they realize you've tricked them."

Mr. Abbott said the birds won't attack fishermen.

"They are big fish eaters and are just looking for an easy meal," he said. But it is unnerving, he added, to have a loon dart under your boat.

"They are great swimmers. You see the checkerboard pattern going right underneath you. It's really something."

Mr. Abbott said he advises sports anglers to play their catch as quickly as possible, so they can release the fish before the loons show up.

"I don't know what else you can do. I think you can kind of look at it as part of the challenge of fishing," he said.

Wayne Campbell, a retired research scientist and the former chief ornithologist of B.C., said loons are adapting their behavior to take advantage of what's available.

"It appears they are just becoming tuned in to a good food source," he said. "They know a good thing when they see it." Mr. Campbell, who receives yearly reports from over 1,000 birders in B.C., said for years there have been occasional reports of loons stealing trout from fishermen.

But in the past few years, those rare reports have become widespread.

Mr. Campbell said with more sports fishermen on the lakes, loons have apparently learned that people aren't a threat to them, but rather can provide access to fish they might otherwise never catch.

"They see that trout flashing around in the water. They know it's healthy, but they know they have a chance of getting it. They know they don't have to spend as much energy to get that fish, so they come right in to the boat."

Mr. Campbell said fishermen should keep their eyes out for loons, and in the spring should avoid the shoreline areas where adults can be seen cruising with their babies.

"In the spring they become very aggressive because of the increased demand for food," he said. "You just have to try to avoid them. But I realize how hard that will be. Loons can swim hundreds of meters underwater."