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Прочитай уривок із статті Bears Are Caring for Their Cubs Longer in Response to Hunting (by ELAINA ZACHOS)
Over the years, several researchers noticed a change in the way that Scandinavian brown bears care for their young. Sweden has one of the fastest bear reproduction rates in the world, and it seems that females were spending more time with their cubs.
"We needed to provide evidence, and then that triggered new questions," says Joanie Van de Walle, a PhD student in the Department of Biology at the Université de Sherbrooke in Quebec, Canada.
Van de Walle is part of an international team of researchers who combed through decades of data on brown bear populations in Sweden to investigate this trend. By following the lives of hundreds of bears, the researchers determined that more mothers are raising their cubs for one year longer than they have in the past.
This behavioral shift can be directly attributed to humans, according to a study published March 27 in Nature Communications. With a population of around 3,000 bears that could be increasing by as much as five percent each year, sustainable hunting tactics can keep bear numbers at bay. This behavioral shift of mother bears caring for their young for a longer time could be directly related to hunting regulations.
In the same way that humans shape wildlife by killing animals, we can also shape wildlife by not killing them. Long-term, this could have implications for brown bear evolution.
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When females keep their cubs around for longer, the mothers reproduce 1_______ often and, long-term, have fewer offspring throughout their lives. But all things considered, the 2_______ lives female brown bears are living counteracts their reduced birth rate.
"The females that 3_______ their young longer, they lose their reproductive opportunity," says Fanie Pelletier, a biology professor at the Université de Sherbrooke. "It kind of cancels out. The composition of the population is different."
4_______ means there will be more adult females entering the population, and hunting will be diverted to male bears and young females without cubs, Van de Walle says. Hunters will continue to shoot females who only keep their cubs for a little over a year, but since fewer mature female bears can be shot, the overall population is 5_______ to continue growing.
If females caring longer for cubs give birth to females who will then care longer for their cubs, this could lead to evolution in the population. In North America, female brown bears already stay with their young for about two and a half years.
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