Brown bears in Sweden wake up from hibernation and go on a reindeer death round
It is not a surprise that bears are some of nature’s most deadly predators, but researchers in Sweden saw a brown bear that was downright murderous.
brown bears (Ursus arctos) overwinters during the winter months and appears in the spring with a voracious appetite. It was this period of activity that conservation experts at Nottingham Trent University, the University of León, Spain and others tried to study when they identified the particularly deadly woman.
Using GPS necklaces, the researchers tracked 15 bears in Norrbotten, Sweden, for two years. There are also flocks of reindeer and moose in the area, and the calving season for the reindeer begins in the spring, just when brown bears come out of hibernation.
These young reindeer calves are particularly vulnerable to hungry bears, with a female bear killing 38 reindeer calves in just one month. When the moose calving season began the following month, the same bear continued to kill 18 moose calves. In total, the bear killed a hoof calf at a rate of almost one a day for two months.
Even more remarkable, they studied the bears changed their hunting grounds after these calving times. When reindeer calving began, the bears moved from the wetlands and coniferous forests to the more barren, higher altitudes that benefit from reindeer raising their young.
Once the moose calving began, the bears moved down to the deciduous forests and the old clear-cutting that moose benefited during this period. After the moose calving was completed, the bears returned to more remote areas away from human activity and fed mostly on berries for the rest of their active period.
“We found that brown bears switched their habitats between calving, reindeer calving, moose calving and post-calving periods,” said Dr Antonio Uzal Fernandez, a conservationist at Nottingham Trent University School of Animal, Rural and Environmental Sciences. in a statement.
“It is clear that a lot of predatory bears reflected the land cover types for reindeer and moose and that they overlapped with seasonally available and vulnerable prey,” he said. “Such a process demonstrates an active hunting strategy for brown bears in the spring, when their diet is more dependent on animal protein than during the rest of the year.”
While the unidentified female bear was particularly prominent in her body number, she was not alone. Eight of the 15 tracked bears were considered “very predators” and usually killed more than 20 newborn reindeer and five newborn moose. The results were recently published in the journal Diversity.
Analysis: Nature is a messy business
It is not surprising that brown bears are deadly predators, but counting their dead puts things in perspective and can help inform about wild management methods in the future.
While the elk herds in Sweden are completely wild, the reindeer are partly domesticated and form a significant part of the indigenous Sami’s economic and cultural life.
Up to 30% of reindeer calves are killed by bears each year, leading to financial losses for the herders. These deaths also have a significant demographic impact on reindeer herds, especially with the loss of female calves, which can threaten the long-term viability of a herd.
Brown bears are slaughtered regularly to prevent over-predation by reindeer herds, so knowing that some bears are more aggressive killers than others is an important discovery.
“Differences between individuals are … important from a management perspective,” said study co-author Andres Ordiz, a conservation biologist at the University of León. “