SUNDAY, May 29 (HealthDay News) -- Attacks by North American black bears on humans are rare, but they appear to be rising as the human population of the United States and Canada increases, new research finds.

The study, published recently in the Journal of Wildlife Management, also dispels the myth that the most dangerous bears to encounter are mothers with cubs to protect. Researchers reveal that lone male black bears hunting people as a potential source of food are to blame for the growing number of deadly maulings.

Between 1900 and 2009, researchers found records of 63 deaths from black bear attacks in Canada, Alaska and the lower 48 states.

About 86 percent of fatal attacks occurred since 1960, and were more likely to occur in Canada and Alaska, where people are more likely to come into contact with bears.

The vast majority of the fatal attacks were predatory (88 percent), and 92 percent of those predatory bears were males.

The study also noted that by examining the nature of black bear attacks, additional fatalities might be prevented. "With training, people can learn to recognize the behavior of a bear that is considering them as prey and deter an attack by taking aggressive action such as fighting back," said Stephen Herrero, professor emeritus at the University of Calgary in a news release.

Among the study's other findings, which may help prevent or manage black bear attacks:

• Bears that have previously killed people are more likely to attack again.
• There is more safety in numbers. Groups of two or more people are much less likely to be attacked.
• Human food and garbage tend to attract bears and may increase the likelihood of serious bear attacks.

"We didn't demonstrate why population growth is correlated with more bear attacks but we suspect it is because there are more people pursuing recreational and commercial activities in black bear habitat," noted Herrero. "Similarly, we don't know exactly why there have been more attacks in Canada and Alaska, but we speculate that it could be because bears in those areas are living in less productive habitat with periodic food stress, which may predispose some bears to consider people as prey."

More information

The U.S. National Parks Service has more tips on how to deter black bear attacks.