Scented snowballs used in park predator test
Billings, Montana - 4/24/03 - Lobbing urine-soaked snowballs toward moose may seem more like a juvenile stunt than scientific research.
But after doing it for five years in the wilds of Alaska and Wyoming, researchers say the experiment may provide important new information about the status of grizzlies and wolves in the Yellowstone ecosystem.
Working for the Wildlife Conservation Society, researchers Joel Berger and Sanjay Pyare exposed female moose to the smells of typical predators, including wolves and grizzlies, to see how they would react.
"They (moose) are not responding the same way as animals under more intense predation," he said.
Similar experiments in Alaska showed that moose ran away quickly when exposed to the smell of predators, Berger said.
The work was reviewed by scientific peers and was recently published in the journal "Biological Conservation."
Berger said he hopes the study will help elevate the debate over removing federal protections for wolves and grizzlies beyond raw population numbers. Instead, a wider perspective needs to be taken that examines the entire ecosystem, including behavioral responses between predator and prey, he said.
"Recovery should be defined by a suite of recovery processes rather than a simple head count," Berger said.
On its face, the work by Berger and Pyare could look a little, well, nutty.
They considered putting a sample on the ground and hoping a moose would walk by. They also considered launching some kind of smell sample by slingshot to a spot near a moose.
Finally they settled on an all-natural, time-tested projectile: the snowball.
On windless winter days with temperatures in the 30s, the researchers trekked into prime moose habitat armed with the urine and feces of various predators such as wolves, grizzlies, coyotes and even tigers.
They then doused a snowball with urine or packed it with feces and then let it fly. Ideally, the snowball landed in the vegetation near where a female moose was foraging. "Control" snowballs without any predator scent were also tossed.
What are they? Researchers in Yellowstone National Park are throwing
urine-soaked snowballs at female moose, which may provide important
new information about the status of grizzlies and wolves in the Yellowstone
Similar experiments were also conducted using recorded sounds of predators.
"It's definitely unorthodox," Berger said. "But it's been reviewed by our (scientific) peers, published in high quality journals and been through the test mill."
The methods may seem funny, but the results offer a clue about predator-prey relationships.
"Typically, the moose in Alaska got highly upset. They would split, leave the area," Berger said.
Most of the moose in Wyoming just ignored the smell, except for moose that had lost calves to wolves.
"They became highly agitated, but the mothers who had not lost calves just stayed put," Berger said. "They were not showing the full range of response where they're part of an active predator system."
The failure by most moose in Wyoming to respond could be a function of the number of elk in the area and that moose simply haven't become a large part of the diet of wolves and grizzlies, Berger said.
But it could also hint at the overall health of the ecosystem, he said.
For the past 75 years, ungulates such as moose, elk and bison in the Yellowstone region have lived in a system free of wolves, which were reintroduced in 1995 and 1996. The grizzly bear population has been growing since federal protections were put in place in the 1970s.
Proposals are expected in the coming years that would remove both species from the Endangered Species List.
According to Berger, the scents of predators are one of several indicators that help biologists understand when carnivores are more fully integrated into the system. Other markers of recovery include restored vegetation communities, birds that rely on certain vegetation and the behavior of other prey species.
"Grizzly bears and wolves in Wyoming are currently protected under the Endangered Species Act, which specifies that recovery includes both the species and the ecological functions it once performed," Berger said. "If these species are delisted, as may be the case in the near future, it will lead the public to the possibly wrong conclusion that grizzly bears and wolves in Wyoming have recovered."
The research, though, isn't meant to advocate for a specific position, he said, but to add information to the debate.
"We just want a full range of material available for people to think about," he said.
Editor's Note: This article was forwarded by Rhoda Cargill, a biologist, who wanted to share it with our readers. She says, "It is either laugh or cry. I am a biologist and this "study" has hole large enough to drive a A-1 tank through."
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