A recent study warns that a proposal to remove grizzly bears and wolves living in the Greater Yellowstone Ecosystem from the Endangered Species List is premature, because neither species may be fully recovered. Federal officials are now moving to delist the largest carnivores of the Greater Yellowstone Ecosystem, citing rising population levels of grizzly bears and wolves as evidence of conservation success. However, the authors of the study say that a simple increase in numbers of wolves and bears does not necessarily mean full ecological recovery. The authors looked at how these formerly absent predators are interacting with moose populations, and found that predator/prey relationships in GYE may show signs of dysfunction.
From the Wildlife Conservation Society :
Yellowstone wolves, grizzlies and moose ‘dysfunctional’ study says
NEW YORK ? (April 15, 2003) A recent study by the Wildlife Conservation Society (WCS) appearing in the journal Biological Conservation warns that a proposal to remove grizzly bears and wolves living in the Greater Yellowstone Ecosystem (GYE) from the Endangered Species List is premature, because neither species may be fully recovered.
Federal officials are now moving to delist the largest carnivores of the Greater Yellowstone Ecosystem, citing rising population levels of grizzly bears and wolves as evidence of conservation success. However, the authors of the study say that a simple increase in numbers of wolves and bears does not necessarily mean full ecological recovery. The authors looked at how these formerly absent predators are interacting with moose populations, and found that predator/prey relationships in (GYE) may show signs of dysfunction.
“The current justification that Yellowstone grizzly bears and wolves should now be removed from their protected status because we have enough of both species now is incomplete,” said WCS researcher Joel Berger, one of the co-authors of the recent study. “Recovery should be defined by a suite of ecological processes rather than a simple headcount.”
For the past 75 years, ungulates such as moose, elk and bison living in the Greater Yellowstone region have lived in an ecosystem free of wolves–which were recently re-introduced in 1995–and grizzly bears–which have recolonized former habitat such as the Jackson Hole area.
Berger and co-author Sanjay Pyare used female moose as an indicator of ecological functionality. They exposed moose to predator sounds and smells, but observed little reaction. Moose in an area of the Kenai Peninsula where moose were fenced in to protect them from predators showed the same disregard for wolf and bear signs.
By contrast, moose living in mainland Alaska, an environment where predators have existed without interruption, displayed agitated responses and often fled the area when predator smells and sounds were present. Berger says that such a reaction indicates the type of response consistent with animals living in an environment containing large predators.
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 these, 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,” said Berger. “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.” Berger and Pyare recommend that the classification of endangered species should include a more complex definition of ecological recovery to ensure that large carnivores become truly restored components of functioning ecosystems.
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