FEMALE brown bears with cubs seem to hang around near people鈥檚 homes. It may be a way to avoid males, who would force the females to abandon their young earlier.
Joanie Van de Walle at Sherbrooke University in Canada and her colleagues studied brown bears living in a rolling landscape of聽managed forests, bogs and lakes in Sweden. The area was dotted with houses and cabins.
Female brown bears keep their cubs for 1.5 or 2.5 years. A female who keeps offspring for 2.5 years can bestow more care, perhaps raising survival chances, but may come into conflict with males who want to mate with her. Males may kill a cub outright, or drive it off.
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鈥淢ales would have an interest in聽shortening the period of maternal care,鈥� says Van de Walle. 鈥淲e thought females might come up聽with counter-tactics.鈥�
To check this, her team used GPS聽collars and helicopters to track 23聽male bears and 16 female bears with cubs. They found that females that only kept cubs for 1.5聽years had similar habitats to males, but females that spent more time close to human homes kept cubs for 2.5聽years (Behavioral Ecology and Sociobiology, ).
In Sweden, hunters aren鈥檛 allowed to kill family groups, so females with cubs have little to fear. In contrast, males and lone females are fair game, so have good reason to avoid places where people live.
鈥淚t鈥檚 a really interesting observation to see these differences in females,鈥� says Dieter Lukas at the聽Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who has studied infanticide by male animals.
However, he isn鈥檛 convinced that the risk of infanticide is what pushes females to venture close to homes. He points out that cubs that go solo aged 1.5 years normally survive.
