25 years after returning to Yellowstone


25 years after returning to Yellowstone, wolves have helped stabilize the ecosystem

New research shows that by reducing populations and thinning out weak and sick animals, wolves have a role in creating resilient elk herds.

ARTICLE BY CHRISTINE PETERSON


PUBLISHED JULY 10, 2020 : READ THE FULL ARTICLE HERE ON NATIONAL GEOGRAPHIC

LARAMIE, WYOMINGTwenty-five years after gray wolves returned to Yellowstone National Park, the predators that some feared would wipe out elk have instead proved to be more of a stabilizing force. New research shows that by reducing populations and thinning out weak and sick animals, wolves are helping create more resilient elk herds.

For the past 12 years, elk numbers in the park’s largest herd have leveled off between about 6,000 and 8,000, instead of extreme boom-and-bust cycles due to climate fluctuations.

“Elk aren’t starving to death anymore,” says Chris Wilmers, a wildlife ecologist at the University of California, Santa Cruz.

During years with normal amounts of rain and snow, wolves primarily kill older cow elk, since they’re the easiest to hunt. But Wilmers led a recent study that showed during particularly dry years—when grass, shrubs, and wildflowers aren’t as lush—wolves switch to hunting bulls. These burly males already don’t eat much in the fall, focusing instead on making deafening bugles and smashing into each other while fighting over cows. All that effort burns calories, weakening them heading into winter. In dry years, they’re even more diminished.

As adaptable, intelligent predators, wolves have learned to recognize these conditions, and they would rather kill an undernourished 750-pound bull versus a 450-pound cow. So by targeting bulls during years of scarce food, they give the cows a chance to reproduce, thus keeping the population afloat. (Explore the Yellowstone most don’t see.)

But most importantly, the Yellowstone area’s wolves—which now number between 300 and 350—could help elk herds weather the perils of a more volatile climate, according to the study, published in the Journal of Animal Ecology. For instance, elk herds that maintain consistent numbers, rather than yo-yoing up and down, can better withstand more frequent droughts—one impact of climate change that is already occurring in the region.

“In a future that will be very unpredictable, we want a buffer” against mass die-offs, says Doug Smith, Yellowstone’s senior wildlife biologist, and wolves’ ability to keep elk herds balanced can play that role. Through hunting and management practices, “humans help stabilize elk populations, but they don’t do the same thing as wolves.” ... READ THE FULL ARTICLE HERE ON NATIONAL GEOGRAPHIC

ARTICLE BY CHRISTINE PETERSON


PUBLISHED JULY 10, 2020 

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