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Moose: Know Thine Enemy

8 February 2001 7:00 pm
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Vigilant mom. A death in the family teaches moose to avoid predators.

The much-maligned moose--think of the thick-headed Bullwinkle--might not be quite so slow after all. New research suggests that moose are as quick witted as Rocky the Flying Squirrel when it comes to figuring out who their enemies are. The findings hint that prey can adapt quickly when new predators, such as wolves or bear, are introduced to a habitat.

Around the world, species are intermingling more abruptly than ever before. Wolves are being reintroduced into areas they haven't roamed for decades; bears are naturally expanding into new ecosystems due in part to greater legal protection. What does such shuffling of species mean, for instance, to a moose that has never seen a bear but is suddenly confronted by one?

To find out, a team led by conservation biologist Joel Berger of the University of Nevada, Reno, and the Wildlife Conservation Society in Bronx, New York, compared the behavior of different populations of moose in North America and Scandinavia. Some weren't familiar with predators (so-called naïve prey) and some were used to them. Berger and his co-workers in Norway found that when naïve moose were confronted with signs of predators, such as calls or scents, they didn't stop feeding and take aggressive stances like moose who were familiar with such threats did.

The researchers also found that moose mortality was higher at the edges of an expanding bear population than in the center of the bear population, leading them to conclude that moose with less exposure to predators were more likely to be killed. But this deadly naïvete was quickly reversible: Female moose whose calves were killed by wolves were dramatically more responsive to wolf calls, the team reports in the 9 February issue of Science. Such moose stopped feeding and looked around for predators for an average of 6 minutes when they heard a wolf call, compared to only 30 seconds for the naïve moose.

The research is good news for reintroduction programs, says wolf re-introduction expert David Mech of the University of Minnesota, Twin Cities. This study, Mech says, confirms researchers' previous assumption that the prey can take care of themselves. But, according to evolutionary biologist John Gittleman of the University of Virginia in Charlottesville, the research raises the point that "it's not effective to do conservation science one species at a time. We need to be thinking along the lines of ecosystems."

Related sites

Joel Berger's faculty page

David Mech's faculty page

John Gittleman's faculty page

The International Wolf Center

The Wildlife Conservation Society

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