Science News

Moose "bear" protective effects of roads in mind

Sun, 14th Oct 2007

Researchers in America's Grand Teton National Parks have found that moose have learned to use roads to shield their calves from grizzly bear attacks.

Writing in Biology Letters, Joel Berger and his team from the US Wildlife Conservation Society describe how they began annually radio tagging 18-25 female moose in 1995. They used the tags to monitor the behaviour and movements of the animals, including where and when they gave birth to young. As time went on the researchers began to notice a pattern emerging. The animals were moving closer and closer to roads to drop their calves, in some cases as near as 50-100 metres.

Now Berger thinks that rising numbers of grizzly bears are the cause. Studies in Alaska show that grizzlies account for 90% of deaths among young moose, but the bears won't go near roads or other signs of human activity, typically remaining over 500 metres away.  Female moose, on the other hand, tend to avoid locations where there are bear droppings, particularly if they have lost a calf to a bear in the past. As a result, the moose are now seeking sanctuary closer to roads.

Support for the theory comes from the observation that only animals in the north of the park seem to be showing a preference for using a nearby road as a nursery - and Yellowstone Park, where grizzlies were granted protected status in 1993 and are now present in large numbers, is only a few tens of kilometres away further north. But the protection of the roadside may be short lived because there are now signs that the bears are becoming more audacious. "So far the bears have avoided these areas," says Berger. "But if you're a hungry bear why wouldn't you go towards the roads?"

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