Brown Bear Super Predator Woke From Hibernation to Massacre 56 Baby Moose and Reindeer

A "highly predatory" brown bear woke from hibernation to massacre 56 baby moose and reindeer, a study has found.

The aggressive female bear was being monitored in Sweden to understand how bears use their landscape.

Brown bears are found several parts of Europe and a survey in 2004 put their numbers in Sweden between 1,635 and 2,840.

The study, published in the journal Diversity, found that when bears emerge from hibernation, they embark on an "active hunting strategy" to take full advantage of the reindeer and moose calving periods.

Researchers monitored this by using GPS collars on 15 bears for two years in Norrbotten, northern Sweden. They also used proximity collars on more than 2,500 adult female reindeer to alert them to close encounters.

The study found that the exact spaces bears occupied varied depending on how many calves they hunted.

However some bears, such as this female, were found to have killed far more than others. She was found to have killed 38 new-born reindeer in just one month. The following month, she killed 18 young moose.

Study author Antonio Uzal Fernandez, an expert in wildlife conservation at the U.K.'s Nottingham Trent University, told Newsweek that the reason why some bears appear more predatory is "complex."

"It must be a combination of different factors ... such as innate behaviour related to personality, but also what they might learn during the early years, physiological conditions, density of prey," he said.

brown bear
A stock photo shows a brown bear. Brown bears were found to move their habitats in synch with the calving season. DrDjJanek/Getty Images

When bears emerged from their hibernation in the spring, and the reindeer calving period started, bears changed their habitat preference from wetlands and coniferous forests, to more rugged terrain and higher elevations—which is favoured by young reindeer.

Once the reindeer calving period ended and the moose calving period began, the bears started to select areas preferred by moose, which included deciduous forests and areas away from public roads.

The study showed that bears killed more during the reindeer calving periods in May. Individual bears classed as "highly predatory"—accounting for eight out of the 15 studied—averaged at about half a kill a day during the reindeer and moose calving periods.

Bears also regularly killed more than 20 new-born reindeer and five new-born moose in a calving period, with one bear averaging about three kills every two days.

Bears such as the highly predatory female may more aggressive and bold than others as they have learned where to find female reindeer and remember each year, the study said.

Researchers said that the findings of this study could help establish possible preventative actions to conflict.

Fernandez said that even the most aggressive bears tend to avoid humans. "The typical response of a bear to an encounter with humans is to run away unless they perceive the human as a threat to themselves or to their young," he said.