New research suggests that mother bears have found a loophole in hunting laws and are using it to protect themselves and their cubs.
It's not easy being a bear in Sweden. While it may be a spectacular place for humans, Scandinavian brown bears (Ursus arctos) are heavily hunted.
A century ago there were fewer than 150 brown bears left in Sweden, but protective measures were enacted and the population grew significantly. Today, the numbers are just shy of around 3,000. But hunting requirements are not that stringent now; anyone can hunt and specific licenses are not required. As AFP reports, hunting season starts in late August and runs to mid-October. Between 2010 and 2014, around 300 bears per year were killed.
However, legislation against shooting mothers with cubs has provided a loophole of sorts – and the bears seem to have noticed, according to a team of international researchers who have spent decades studying Scandinavian brown bears.
In their study, published in the journal Nature Communications, the researchers conclude that females appear to have learned to protect themselves by sticking with their cubs for longer. Some have extended their time with cubs from 18 months to 30, increasing survival rates for both mom and offspring.
In the decade between 2005 and 2015, the number of mothers keeping their young with them for an extra year increased from seven percent to 36 percent.
"A single female in Sweden is four times more likely to be shot as one with a cub," says Professor Jon Swenson, one of the authors of the study, and who has spent more than 30 years working with the long-running research projects on bears. "As long as a female has cubs, she is safe. This hunting pressure has resulted in a change in the proportion of females that keep their cubs for 1.5 years in relation to those that keep them for 2.5 years."
While mothers spending less time on maternal care would obviously lead to more reproductive successes, the researchers found that this was offset by the higher survival rate among both the mothers and their cubs.
"In an evolutionary perspective, this would not be beneficial," Swenson says. "The animals with the most offspring [are the most successful]."
But the females' increased lifespan apparently counters the reduced birth rates. "This is especially true in areas of high hunting pressure. There the females that keep their cubs the extra year have the greatest advantage," says Swenson.
Not the least of which is not being shot by a hunter.
For more, visit the Skandinaviska Björnprojektet; AKA the Scandinavian Brown Bear Research Project.