A single female in Sweden is four times more likely to be shot as one with a cub.
Female brown bears have learnt to protect themselves from hunters by keeping their cubs closer for longer, according to a new study. In Sweden it is legal to hunt Scandinavian brown bears, but bears in family groups are protected by law.
Professor Jon Swenson, from the Norwegian University of Life Sciences and co-author of the report, said: "A single female in Sweden is four times more likely to be shot as one with a cub.”
The findings come from one of the world’s longest-running research projects on bears. Swenson has been working on the survey for more than 30 years. He said: “Generally, the cubs followed their mother for one-and-a-half years.”
But over the course of the study the researchers have found that some female bears began to change their mothering strategies to increase their chances of survival.
Between 2005 and 2015, the number of females keeping their cubs with them for an extra year rose from seven percent to 36 percent.
But although these new tactics improve the life expectancy of those females who keep their young for longer, they also reproduce less often and reduce their total number of offspring.
The researchers note this might not be advantageous from an evolutionary perspective. Swenson added: “The animals with the most offspring 'win' nature’s race.”
But the results also show that the increased life of the females largely counteracts the reduced birth rate.
Swenson concludes: “This is especially true in areas of high hunting pressure. There the females that keep their cubs the extra year have the greatest advantage.”
Catherine Harte is a contributing editor to The Ecologist. This story is based on a news release from the Norwegian University of Life Sciences. The full report is published in the journal Nature Communications.