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Bison, Pine Nuts, Trout and Grizzlies: Perfect Storm For Yellowstone National Park's Wildlife Managers?
Yellowstone National Park's northern range at times has been labeled "America's Serengeti" for the rich and diverse wildlife that inhabits it. But today, with native trout imperiled by non-native predators, whitebark pine trees falling to climate change, and bison being cut off from valuable winter habitat and at times slaughtered, is the ecosystem unraveling?
We're already seeing evidence of the collapse of the Yellowstone cutthroat trout fishery in Yellowstone Lake due to a non-native species, and the possible downfall of a key species of pine. If that's not bad enough, now some fear the park's grizzly bears stand to suffer the consequences when you combine those two events with the pressures being placed on the park's bison herds.
Is this collision of ecosystem maladies coalescing into a significant wallop that will reorder some of the key dynamics of Yellowstone's natural world? Or is the park resilient enough to rebound, albeit with some significant help from wildlife managers?
It was only three years ago that officials from the park, the state of Montana, and various conservation groups were roundly applauding a $2.8 million deal envisioned to stretch Yellowstone's northern range a bit further into Montana for the benefit of the park's bison.
But look where we are today. A test group of 25 bison has failed to successfully make a go of it in the Gallatin National Forest north of the park. Dozens of bison now are being targeted for slaughter (although the courts could step in to direct bison management issues). And grizzly bears are said to be at risk due to a protein-short diet,
How healthy is Yellowstone's Serengeti?
Yellowstone has over the decades clearly demonstrated its resilience. It rebounded from the unhealthy practice of feeding bears at garbage dumps, the extirpation of wolves from its landscape, and from the heavy handed management of elk in the 1960s.
But all those events were orchestrated by the human hand.
Today we also must take into consideration climate change, which is threatening to decimate a species of tree -- whitebark pine -- that produces a nutritious nut that Yellowstone's grizzlies rely on as an integral part of their diet.
To the struggles of the fish, the tree, and the bears (already a threatened species), add the bison. Long considered iconic animals -- they grace the logos of both the Interior Department and the National Park Service -- these days bison are viewed by livestock interests in Montana as disease-laden intruders.
Some of those bison that head into Montana find themselves targeted by hunters, others have been rounded up and sent to slaughter by the Park Service. According to numbers tracked by Earthjustice, a non-profit legal firm that works to protect natural resources, during the winter of 2005-06 "state and federal agencies shipped to slaughter more than 900 bison," and during the winter of 2007-08 more than 1,400 more bison were sent to slaughter.
While that $2.8 million, 2008 deal envisioned Yellowstone bison being allowed to roam from the park, across the Royal Teton Ranch, and into the Gallatin National Forest, when the very first 25 bison were "encouraged" by hazers to move north last month, the experiment quickly failed. Not long after those bison reached the Gallatin, wildlife managers and livestock agents had trouble keeping them on the forest lands and away from private lands. One bison was shot and killed when efforts to haze it back onto the national forest failed.
Today, the surviving 24 bison are either back in the park or being held in the park's Stephens Creek capture facility.
Against that backdrop, Earthjustice's attorneys the other day requested that the partners of the Interagency Bison Management Plan -- Yellowstone Park, Gallatin National Forest, Montana Fish, Wildlife and Parks, Montana Department of Livestock, and the U.S. Department of Agriculture's Animal and Plant Health Inspection Service -- reconsider the current approach to bison management in terms of how it is impacting Yellowstone's grizzlies, a threatened species. Removing large numbers of bison from the park's herds, they maintained, adversely affects the diets of Yellowstone's grizzlies.
A major driver behind the request, Earthjustice attorney Tim Preso said Tuesday during a phone call, is the decline of high-elevation stands of whitebark pine. Once inhabiting an empire along the roof of the Rockies too cold for mountain pine beetles to endure, the trees now are being feasted upon, and killed, by pine beetles that are able under the warming climate to reach the whitebark stands. The decline of whitebark pines is leading to a decline in calorie-rich pine nuts that some Yellowstone grizzlies depend upon, he said.
“We have seen the demise of one of the key food sources for the population in the form of the whitebark pine, the seed cones. While it is one of sort of four pillars of the grizzly bear nutrition source in the Yellowstone ecosystem, in many ways it was extremely important and perhaps more important than many others," Mr. Preso explained.
While grizzlies long have had carrion in the form of elk and bison carcasses to feed upon, along with cutthroat trout that head up streams to spawn, plus vegetation, the value of the whitebark pines lies in the fact that they grow at high, remote elevations, and have been a food primarily sought by female grizzlies, he said. The pine nuts were rich in calories and allowed grizzly sows a nutritional resource they didn't have to battle a boar over.
"You had bears out of the way of people during the time of the year when they were using this food source, which happened to coincide with both late-season pre-hibernation feasting process, hyperphagia, but also it was a food that was heavily exploited by female bears," said the lawyer. "And they didn’t have to get down and mix it up with males over (bison) carcasses in order to exploit this food source."
But while evidence has been mounting that whitebark pines are in danger of being wiped out for all practical purposes by pine beetles, so far government officials, he said, have ignored arguments about how the loss of whitebark pines would jeopardize Yellowstone's grizzly population.
“The government’s answer to that has been, ‘Don’t worry about it, grizzly bears in Yellowstone have a lot of choices on the menu and there’s a lot of meat on the hoof, so we’re good,'" said Mr. Preso. "I think that’s not a very convincing response, honestly, because of a number of things. Not least it overlooks the dynamics of having a female out there having to spar with dominant males over carcasses as opposed to having a relatively secure food source in the high elevation white-bark pine zone.
“But also because here we are, managing bison in a way that’s removing lots of calories from the ecosystem, and that's a concern we’re trying to raise.”
The issue of declining whitebark pine trees and grizzly diets actually was touched upon more than a decade ago, in 2000, by the U.S. Fish and Wildlife Service when it reviewed the IBMT's plan for managing Yellowstone bison:
[U]ngulate meat may become even more important to the nutritional well-being of
grizzly bears if whitebark pine seeds and cutthroat trout are reduced by introduced
organisms. The draft Conservation Strategy for Grizzly Bears in the Yellowstone
Area (November 1999) calls for monitoring these and other grizzly bear foods.
The Interagency Grizzly Bear Study Team is currently conducting whitebark pine
transects in the Yellowstone ecosystem and the Park is monitoring the effects of
lake trout reduction efforts on cutthroat trout population trends. If such research
or other information should suggest a decline in whitebark pine seed production
or other key grizzly bear foods to levels that would impact grizzly bear nutritional
status, an additional evaluation of the bison management plan should occur. The
evaluation should examine, among other issues, whether bison management is
substantively limiting the number of bison carcasses available to grizzly bears or
whether the plan could be modified to allow bison to provide additional food
resources for bears. (emphasis added)
While Mr. Preso wouldn't hazard a guess as to how many calories -- or bison carcasses -- the current bison management plan was depriving Yellowstone's grizzlies of, he did point to a 1997 study by wildlife biologist David Mattson that noted the value of bison to the park's bears.
"The Mattson study documented that the amount of bison consumed by Yellowstone grizzly bears was three times greater than the amount expected as a result of the relative numbers of bison within the grizzlies’ range. Moreover, meat obtained from scavenged adult male bison provided the single largest contribution of any source (15.8 percent) to total biomass consumed by Yellowstone grizzly bears from the various ungulate types observed in the Mattson study," he wrote in his letter to the IBMP partners. "Scientific evidence also demonstrates that grizzly bear reliance on the meat of bison and other ungulates in the Greater Yellowstone Ecosystem is 'in part compensatory to limited availability and use of whitebark pine nuts.' During the historical period when whitebark pine stands remained vibrant across the ecosystem but varied in their annual seed-cone production, Yellowstone grizzly bear use of ungulate meat as a food source was 2.1 times greater during years when the bears did not use whitebark pine seeds than during years when they did, prompting Mattson to describe the relationship between these food sources as 'mutually exclusive.'
"As summarized by the Interagency Grizzly Bear Study Team, the best available scientific evidence 'clearly shows that bears tend to eat more meat when whitebark pine seeds are not available and that there is an increase in hunter-grizzly bear conflicts and bear mortalities in poor seed years.'"
The attorney said the current approach to managing bison can't be overlooked in terms of its impact on grizzlies when the bears' other food sources are being compromised.
“It’s a significant piece of a shrinking puzzle in terms of the overall nutritional puzzle for Yellowstone grizzly bears. And here we are shipping -- and not to hide the ball, we don’t like the bison slaughter for all kinds of reasons, including what it does to the bison herd and what it does to the national park when you have the Park Service slaughtering native wildlife in the interest of livestock owners outside the park boundaries, all of that is objectionable for a lot of reasons -- but the grizzly bear issue is a very significant one as we’ve entered this new world of no whitebark pine and declining fisheries," said Mr. Preso.
At Yellowstone, spokesman Al Nash couldn't immediately respond to the issues raised by Mr. Preso, saying park officials just received the request Monday, but said a response would be forthcoming.