According to a new study observing the behavior of bears, a “highly predatory” 13-year-old female brown bear woke up from hibernation and killed 38 reindeer calves within 30 days, and then 19 young moose the next month.
The study was observing 15 brown bears in northern Sweden that were wearing GPS collars with technology in them that could tell when the bears made a kill.
Researchers were mainly looking to understand how the bears use their landscape and what they learned was that some bears are more predatorial and they change their hunting habitats to target reindeer and moose calves during the spring.
Why are some bears more predatory?
“It must be a combination of different factors,” study co-author Antonio Uzal Fernandez, a senior lecturer in wildlife conservation at Nottingham Trent University in the U.K., told Live Science in an email, “such as innate behaviour related to personality (for instance, some people are more aggressive than others).”
Even though some bears are more predatorial, the researchers say that it doesn’t indicate that they pose more of a threat to humans.
The more predatorial bears were actually recorded to hunt in the high-elevation, rugged terrain preferred by reindeer with young, and then would move on to calving moose deep in the forests.
The high-predatory bears favored forested areas occupied by more reindeer than the more open areas that low-predatory bears would typically select.
Researchers said that the average bear makes 0.4 kills per day and eight of the 15 bears were categorized as highly predatory. Meaning, they regularly killed more than 20 reindeer calves and 5 moose calves in a calving period.
The report said that the bears were not as effective at hunting larger adult prey so they focused on hunting the calves until July when they switch their diets to mainly eating berries for the rest of the year until hibernation.
“Our study shows the differences between individual bears’ predatory behaviour and how this helps to explain individual variation in their habitat selection,” Fernandez said. “Differences among individuals are also important from a management perspective; for instance, mere predator removal, without targeting specific individuals, may not necessarily reduce conflict.” That’s because some bears are more aggressive and bolder than others.