Real-life “care bears” in Sweden have responded to human hunting by increasing the time they look after their cubs, researchers have found.
Over a period of 20 years, the length of time the brown bear cubs stayed with their mothers increased from 1.5 to 2.5 years.
Extending the care of their offspring by a year means that the female bears have fewer breeding opportunities. But the research showed how this was outweighed by longer survival of both mothers and cubs.
Between 2010 and 2014, Swedish hunters shot around 300 bears each year.
However, like many other countries that allow bear hunting, Sweden bans the shooting of bears in family groups.
Lead researcher Professor Jon Swenson, from the Nowegian University of Life Sciences, said: “A single female in Sweden is four times more likely to be shot as one with a cub.”
The pressure of hunting, combined with hunting regulations, had led to a profound change in behaviour that was spreading through Swedish bear populations.
“Man is now an evolutionary force in the lives of the bears,” Prof Swenson added.
Mother bears who kept their cubs for longer were safer, but ended up producing fewer offspring, said the scientists writing in the journal Nature Communications.
While this would not normally be a good strategy from an evolutionary perspective, the female bears’ increased survival chances largely counteracted the reduced birth rate.
“This is especially true in areas of high hunting pressure,” said Prof Swenson. “There, the females that keep the cubs the extra year have the greatest advantage.”