Bears have killed his livestock and preyed on sick calves. They tear open silage bags and break into grain bins.

But the real fear for Tony Bruder, a third-generation Twin Butte cattle rancher, is that one day it will be a human at the ugly end of a bear's attention.

He's been chased by a bear while on horseback, and had grizzlies stroll by while he works under farm equipment. He's watched his children head out the back door to catch the school bus, and a bear wander through moments later.

"Sure, these bears are doing this damage," he said. "But it's not going to be long before it gets one of our kids or one of us or somebody walking down the road doing a little hike."

During the last number of years, Bruder says, human-bear conflicts have increased dramatically.

He and other ranchers are placing part of the blame squarely on the shoulders of an unusual culprit -- bovine spongiform encephalopathy.

The link is not an obvious one. But ranchers say regulations imposed by the federal government since a case of the disease was found in an Alberta cow in 2003 have changed how they dispose of cattle that die on the ranch, creating in the process a huge attractant for bears.

Rather than shipping carcasses off the farm, ranchers for several years have simply been hauling them to a remote part of the property and leaving them to decay in boneyards.

"It's just fat city," says grizzly bear expert Mark Boyce, a professor at the University of Alberta. Carnivores, he says, are heading to boneyards to feast.

There was a time before BSE when the rendering company would pick up a dead cow that has died of such things as old age or illness for free. It was a good deal in two ways: the rancher could get rid of a carcass at no cost, and the renderer could make some money off the dead stock.

But with significant restrictions now placed on how dead cattle are rendered, those days are long gone. Renderers aren't making as much money off a carcass and are now charging to ship it off a ranch. It now costs a minimum of $75, or nine cents a pound above that, to transport a dead cow.

"We're now paying about $100 to have a dead cow picked up," Bruder said.

That's left ranchers in a serious quandary. With margins so tight, few are willing to pay the cost. Instead, they might drag a carcass to the far end of the ranch and simply let nature take its course.

But it's not just ranchers in the area who are noticing the increase in human bear conflicts. Grizzly bear researchers at the University of Alberta have also observed the trend.

"These boneyards are very major attractants," Boyce says. "There's a very substantial increase in the human-bear conflict that's occurred just during the past five years. It's very marked."

Grizzly bear conflicts have more than doubled since 2003 in bear country running east of the British Columbia border and south of Highway 3, according to data compiled by U of A master's student Joe Northrup. Last year, there were roughly 40 conflicts reported in the area.

"When bears become used to those sorts of food resources, they can become desensitized to people," Northrup said. "They become bolder, might start coming closer to houses."

Northrup's research looked at 314 grizzly bear conflicts during the last 10 years. More than one-quarter of bear conflicts dealt with dead stock. Another 15 per cent dealt with bears killing livestock.

Before BSE, an average of 1,000 cattle carcasses a year in the Municipal District of Pincher Creek were being carted away by the renderer, according to rancher Richard Hardy.

Since BSE, the number has dropped to just 200 a year. The rest are simply being left on the farm to be scavenged by bears, wolves and other carnivores.

"It has increased tremendously since BSE," Hardy said of boneyards.

Bear problems have become so acute that ranchers like Hardy and Bruder have banded together to work out some solutions. With some support from Alberta Sustainable Resource Development and a private sponsor, a number of bear-proof bins have been purchased.

Ranchers, after obtaining permits from the Canadian Food Inspection Agency, can dump carcasses in the bins, which provide a central depot for the renderer and reduces costs, Bruder said.

Ranchers note that boneyards aren't the only thing attracting bears. The animals are also getting into grain bins, and ranchers are working with Sustainable Resource Development to replace older containers with bear-proof bins.

In an attempt to keep bears away from people, the department also drops carcasses from a helicopter when bears emerge from their dens, according to spokesman Darcy Whiteside.

At issue with the disposal of carcasses is specified risk material (SRM), which is certain cattle tissue capable of transmitting BSE.

Before BSE, one plant would typically render poultry, pork and beef, according to Geoff Smolkin, manager with Alberta Processing Co. But after BSE, those plants had to specialize, increasing the transportation costs of shipping carcasses. Restrictions also limited what dead cattle could be used for, he said.

"That's added more costs to the business," he said. "At one time, we were selling the product. Now we're rendering, and the meat and bone meal from the cattle has to go to landfill."

For its part, the Canadian Food Inspection Agency says the best bet right now is for ranchers to work with their local communities and the province to come up with solutions and money to transport carcasses off farms.

But in the long-term, the solution will likely be in new technology, says Reza Hejazi, a disease control special with the food inspection agency who specializes in SRM.

He says there are three or four projects underway in Western Canada dealing with the disposal of carcasses. For instance, dead stock could be turned into fertilizer. That, he says, would make for a value-added product, but also put some money back in the pockets of ranchers.

"There are other ways we can come up with better solutions, technology-wise, to turn this material to products that we can put back to earth in a very environmentally friendly way," he said.