WITHOUT BEARS AND WOLVES TO HUNT THEM,YELLOWSTONE MOOSE HAVE LOST SOME SPRING IN THEIR STEP, STUDY SAYS
As people learn to live with grizzly bears and wolves that have recolonized areas around southern Yellowstone National Park after a 50-year absence, so too must moose, which apparently have forgotten to recognize predators, according to a study funded by the Bronx Zoo-based Wildlife Conservation Society (WCS).
Published in the Feb. 9th issue of the journal Science, the study shows that moose failed to acknowledge bears and wolves as threats when they encountered them for the first time, leading to initially high levels of predation among these ungulates.
"Just as many of the New World's wildlife suffered high mortality and even extinction upon first contact with colonizing humans, so it appears that moose may not recognize bears and wolves, even though they have only been absent from the study area for 10-15 generations," said WCS researcher Dr. Joel Beger of the University of Nevada, the study's lead author.
Berger and his colleagues looked at moose populations at sites in Yellowstone and Scandanavia, where grizzly bears and wolves have only recently returned, and compared them to populations in Alaska, where predators never left. The scientists exposed the moose to predator "cues," which included recordings of wolf howls and coyote calls, as well as the scents of both grizzlies and wolves. To gather data, the researchers capitalized on unique methods, some of which included the use of human urine as a control substance, and occasional reliance on a moose suit to approach their subjects.
In predator-free areas, moose were six times less likely to recognize these carnivore cues than in Alaska, where similar exposure would frequently cause them to stop feeding or adopt an aggressive-defensive posture.
But the scientists say that moose are a quick study when it comes to other animals trying to eat them. For example, the authors found that moose mothers whose calves were killed in the Jackson Hole area, became 5 times more sensitive to wolf calls.
"Wyoming moose that have lost even one of their offspring to predators may become as savvy as their Alaskan cousins within a single generation, which indicates that mechanisms for predator avoidance are already in place, and that fears of imminent extinction may be unwarranted," Berger said.
WCS is currently looking at a variety of wildlife issues in the Greater Yellowstone Ecosystem, which comprises Yellowstone and Grand Teton National Parks as well as outlying areas. Other studies include the displacement of mountain lions by wolves, which kill mountain lion cubs, and the effects of the disease brucellosis on bison populations.
"What the Serengeti is to Africa, Yellowstone is to America - a living museum of what the American west largely looked like hundreds of years ago. If our science can help us understand predator-prey dynamics, and simultaneously help preserve the critical wildlife living in this ecosystem, than we will have succeeded," said Berger.
COPIES OF THE SCIENCE ARTICLE ARE AVAILABLE THROUGH AAAS NEWS & INFORMATION OFFICE (202-326-6634); PHOTOS AVAILABLE THROUGH WCS.
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