Grizzly bear with bison carcass, Yellowstone National Park. Photo: YellowstoneNPS via Flickr.com.
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Yellowstone grizzlies face trophy-hunting threat
31st January 2014
Yellowstone's Grizzly bears are facing multiple threats, writes Anna Taylor - from proposals to remove their protection under the US Endangered Species Act, and shortages of key foods caused by climate change.
Delisting would leave grizzly bears on permanent life support, and push the bear back to the brink of extinction.
Trophy hunting of Yellowstone National Park's Grizzly bears may resume in 2014 if the proposal to remove the bears from the protection of the Endangered Species Act is approved later this year.
The grizzlies would still be protected from hunting in the Park itself, however it accounts for under a fifth of the 9 million acres the bears inhabit in and around Yellowstone - and it would be legal to shoot them the moment they step over the Park boundary.
The Yellowstone Ecosystem Subcommittee of the Inter-agency Grizzly Bear Committee recently recommended to the US Fish and Wildlife Service that the bears be de-listed.
The advice followed the publication of a controversial report by the Inter-Agency Grizzly Bear Study Team on 2nd December: Response of Yellowstone's Grizzly bears to changes in food resources - a synthesis.
In summary, the Synthesis report argues that the Park's grizzlies are doing just fine, indeed that they are now limited in numbers only by the ecosystem's "carrying capacity".
However other scientists contest the Synthesis Report's findings and criticise it as incomplete, flawed and "politically motivated".
Mountain pine beetle
Key to the debate is the grizzlies most important food: the fatty, nutritious seeds of Whitebark pines.
Whitebark pine trees are increasingly falling victim to mountain pine beetle, which kills the trees when it lays its eggs under the bark. Whitebark pines are found at high elevations, typically over 2,500m, but climate change is making them more accessible to the pests.
A study conducted last year discovered that 16 of the 22 major mountain ranges in Yellowstone have experienced widespread moderate-to-severe mortality of whitebark pine - 82% of its total distribution.
The reason why whitebark pines are so important for Grizzly bears is that their seeds are a rich source of dietary fat (30-50%).
The fat is not only a great source of daily energy - it's also efficiently converted to body fat. And that promotes the survival and reproduction of female grizzlies, for hibernation and also to support lactation.
While acknowledging the importance of the pine seeds, the Synthesis Report controversially claims that the Grizzly bears have suffered "no profound negative effects" from the loss of whitebark pine seeds and demonstrated "notable resilience" by moving to other food sources.
Pine nuts are key to Grizzly bear success
In fact, scientists have found that females who ate more pine seeds gave birth to more cubs, and were more likely to reproduce in any given year, compared to females who ate fewer pine seeds.
There is a strong historical relationship between Whitebark pine seed crop size and Grizzly bear survival in Yellowstone - and many Whitebark pines in the National Park are dead or dying.
So Grizzly bear scientists are baffled by the Synthesis Report's conclusions, and the subsequent recommendation to remove legal protections.
One such scientist, Dr David Mattson, has written a scathing attack on the Synthesis Report, describing some of the claims it makes as "shoddy science", "nonsense" and "bemusing".
Multiple dangers downplayed
The report downplays the link between pine seeds and Grizzly bear health, as well as the decline in grizzly bear fat composition, first noted in 2006 when the impact of the loss of whitebark pine began to be felt.
The authors claim that grizzlies can compensate for loss of whitebark pine seeds by eating more meat. Yet this is the most hazardous food for the bears to eat because they expose themselves, particularly cubs and yearlings, to the threat of wolves and other bears at the food source.
The Synthesis Report also completely ignores worrying declines of other prey species such as cutthroat trout and elk. Elk numbers are already falling and the decline is expected to gather pace as a result of drought and climate change.
But as the Center for Biological Diversity (CBD) observes, the study fails to consider the effects of the elk population decline, which it describes as "a development that's likely to increase the risk of conflict and mortality for bears that eat more meat."
"There is not a single positive trend afoot in Yellowstone's grizzly bear habitat", says Dr Mattson. "What we have is a habitat fabric that is simply unravelling."
The threat of the human
There is also an increased threat from humans. Whitebark pines grow at higher elevations, so when consuming the seeds (mostly from squirrel caches) they are well away from human activity.
But when the pine seed crop is small, the bears are found at lower elevations seeking out alternative foods - like clover or yampa roots.
This also brings them closer to roads, resorts and towns, and into conflict with hunters and ranchers if the bears attack their livestock. The likely result is an increase in bear deaths at the hands of humans.
Where's the data?
Another serious flaw in the Synthesis Report is that many of the studies it refers to have not undergone peer-review, nor have they been published in scientific journals.
This runs directly against federal science protocols as it means the data used is both of questionable quality, and may be unavailable to other researchers for thorough examination.
On 12th December 2013 the CBD filed a freedom of Information request for all the data underlying the Synthesis Report.
The Inter-Agency Grizzly Bear Study Team, says CBD's grizzly bear conservation advocate Louisa Willcox, "is cherry-picking the data to get the result it needs to justify delisting, while refusing to release the data it used to reach its conclusions.
"In reality top grizzly researchers say the bear population has likely been in significant decline for five years."
Self-contradictions in the Synthesis Report
The Synthesis Report is also riddled with self-contradictions. On the one hand, it admits that the pine seeds are a strongly favoured food source.
But it also claims that when the pine seeds are in short supply, it makes no difference to the bears as they can simply switch to other foods.
It also says the slow-down in Grizzly bear population growth since the early 2000s has taken place because "the population is near carrying capacity".
However this is to disregard two things. Many scientists, including those working for CBD, believe that the population has actually been declining for several years, rather than just increasing at a slower rate.
It also fails to recognise that availability of food is the main determinant of an area's carrying capacity - and that if the most important food is in short supply, that must have a dramatic effect on population dynamics.
Confusion rules the day
Most astonishing is the Synthesis Report's conclusion that "the change in population trajectory was more associated with grizzly bear density, primarily through reduced cub survival and reproductive transition, rather than whitebark pine decline."
After all, "reduced cub survival and reproductive transition" is precisely how the reduced supply of whitebark pine seeds would be expected to manifest.
The Synthesis Report also fails to explain why, if the Yellowstone Park is truly at its maximum at carrying capacity for grizzlies, the bears have failed to move into large stretches of suitable habitat outside the Park's boundaries.
The final conclusion speaks for itself: "the increase in number of mortalities is unlikely to have affected population growth."
Or in plain speaking: "we think we start shooting Grizzly bears, without making any difference to their numbers."
Political motivations at work?
This has led many to believe that the report was motivated by the political interests of wildlife management agencies in Idaho, Montana and Wyoming.
All three have been open about their desire to see grizzlies delisted so that they can take over their management and institute a sport hunt.
"The push to drop protection is being driven by states hostile to large carnivores", comments Willcox.
"But these bears have the lowest reproductive rate of any North American mammal. Hunting and other causes of death are certain to reverse the progress that's been made toward recovery."
She adds that trophy hunting will not take place in the Yellowstone Park itself, nor in nearby Grand Teton Park, as a general hunting ban is in place. But without ESA protection, they will be vulnerable whenever they venture outside the Park.
"Even though Yellowstone is big, at about 2 million acres, Grizzly bears roam widely and are currently using more like 9 million acres. With all but Yellowstone and Grand Teton parks open to hunting, we will undoubtedly see Yellowstone's iconic bears shot and carried off as trophies."
Time for a public outcry
The next step is for a delisting plan to be drawn up by the US Fish and Wildlife Service, which will then be open for public comment.
Public outcry and lawsuits by environmental organisations are certain to attempt to prevent the delisting. As Willcox explains, "Delisting would leave grizzly bears on permanent life support, and push the bear back to the brink of extinction."
"There's still a chance to reconnect Yellowstone to other grizzly bear populations and recover grizzly bears in the lower 48, but not if Yellowstone's population is prematurely delisted and subsequently crashes."
Delisting of the Yellowstone bears and associated hunting "would leave this grizzly bear population permanently isolated from other grizzly bears. This means that bears would need to be trucked into Yellowstone to avoid genetic inbreeding."
Or as Dr Mattson puts it, continued protection under the EPA "makes it more likely that bears can continue to spread out into areas we know are suitable for bears." This would bring the Yellowstone grizzlies into contact with other populations, making them all less vulnerable.
Anna Taylor is a freelance science journalist, specialising in environmental issues and new discoveries in conservation biology. She posts regular blogs on Conservation Jobs.
Anna has also worked in conservation and conservation research for RSPB and other employers in the UK, Africa and the Amazon. She has a BSc in Conservation Biology and a Masters in Ecology and Environmental Biology.
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