Steyaert said that he and his team aren't sure how this all developed.
"It might be a learned strategy or an individual tactic," he said. "There is a lot of individual variation in behavior in bears, and personality may play a big role in there."
Nearly all bears fear humans to some degree, and for good reason. Hunting bears in the Swedish wilderness is popular. So mother bears and their cubs settle in areas that are close, but usually not too close, to humans.
"The median distance from human habitation for successful mothers was about 700 meters (.4 miles), so it is not that these mothers are in the backyards of people all of the time, but they are in relative close proximity," Steyaert said.
The new findings could help explain why so many unexpected human encounters with bears in North America, Europe and Asia involve mothers and their cubs.
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Marcus Elfström, a biologist at the Sweden-based organization EnviroPlanning, told Discovery News that the study "provides evidence that female bears can increase their reproductive success by using human footprint as a shield against infanticide."
Elfström said that the most accepted explanation is that bears associate people with easily accessible food. Earlier studies from the Scandinavian Brown Bear Research Project, however, have found that the physical condition of bears close to settlements vs. bears that were in more remote regions were basically the same.