top of page
  • David Mattson

Through the Climate Looking Glass into Grizzly Wonderland

by David Mattson

Strangely enough, grizzly bear researchers and managers seem to have integrated a faith-based version of climate-change-denial into their collective world view. In fact, these ostensibly well-educated men and women bring to mind well-schooled ecclesiastics professing a belief system: “Grizzly bears are omnivores. Grizzly bears are adaptable. Grizzly bears are unaffected by changes in habitat and foods. Climate change has not affected grizzly bears. Climate change will not affect grizzly bears.” The US Fish & Wildlife Service has gone so far as to baldly assert “…ever,” which is, needless to say, a very long time.

Or, alternately, an image comes to mind of grade-schoolers sitting rigidly at attention reciting their multiplication tables, only, in this case, the recitation is: “Two times two equals four. Three times three equals six. Four times four equals eight…” There is a certain superficial logic that nonetheless perverts reality.

With perhaps a bit more disingenuousness, researchers on Yellowstone’s Interagency Grizzly Bear Study Team routinely dissemble: “We looked really hard to find any effect of climate change on grizzly bears but just couldn’t find any. In any case, we found that grizzlies eat more than 200 different foods.” A conclusion, it turns out, that is not a result of studious independent-minded inquiry, but rather the outcome of poorly-designed, prejudiced, and unreplicable science.

All of this is a problem, especially for those of us who look for fact rather than fiction and faith as a basis for crafting and fulfilling public policy—including in our treatment of grizzly bears.

A Corrective for the Rhetoric

Despite Trump’s record-breaking efforts to substitute fiction for fact, I can only hope that the truth still matters to most people. Based on this perhaps blithe hope, a corrective to the climate-change-denial rhetoric of grizzly bear researchers and managers is warranted. With this purpose in mind, what follows are my thoughts, point by point, in response to the government mantra:

Grizzly Bears are Omnivores, But…

Grizzly bears are omnivores, but as with all omnivores, including humans, this does not mean that they fare well on all foods. As it turns out, the digestibility and nutritional quality of bear foods vary by orders-of-magnitude. A salad does not equal a steak. Moreover, bears, like humans, need a balance of energy and nutrients, which means that an endless diet of either steak or blueberries can be problematic in its own right.

Grizzly Bears are Adaptable, But…

Grizzly bears are adaptable, but not infinitely so. There are real-life consequences for their survival and reproduction depending on what, when, and where foods are available, especially vis-à-vis people, who kill roughly 80-90% of all the adolescent and adult bears that die, but also vis-à-vis other bears, that routinely kill cubs and compete for food.

Grizzly Bears are Affected by Habitats and Diets

Grizzly bears are affected by changes in habitat and foods. At the risk of being repetitive, omnivory does not make them immune to changes in food quality and quantity, nor does “adaptability” make them immune from the human- and bear-related hazards associated with eating certain foods in certain areas.

Evidence for this can be found in the fact that rates and causes of bear deaths have changed dramatically in the Yellowstone ecosystem as a direct result of shifts in distributions and diets, driven by changes in food availability (e.g., whitebark pine, cutthroat trout, army cutworm moths, elk, and bison)—driven in turn by wildfires (whitebark pine), drought (elk), pathogens (whitebark pine and trout), sport harvests (elk), perverse politics (bison), and invasions of non-native species (whitebark pine and trout, again).

More conclusively, the profound effect of habitats and diets is evident in orders-of-magnitude differences in densities of grizzly and brown bears worldwide unambiguously rooted in the quality, quantity, and distributions of foods.

Grizzly Bears Have Been Adversely Affected by Climate Change

Grizzly bears have been affected by climate change. Our most conclusive evidence comes from the Yellowstone ecosystem where dietary staples have already been more or less driven off the menu by climate change, with resulting deleterious changes in bear behaviors.

Whitebark pine has been functionally eliminated in most parts of the ecosystem as a result of bark-beetle-caused mortality unleashed by climate warming in the formerly frigid haunts of whitebark pine. Cutthroat trout has been devastated by predation from a non-native predatory fish—Lake trout—but with the effects of this predation compounded by deteriorating hydrologic conditions in streams used by cutthroat trout to spawn. Elk herds have declined, even plummeted, from a lethal brew of stressors that include deteriorating range conditions during late summer caused by climate warming. Increased predation by grizzly bears on elk calves has exacerbated negative trends. Notably, much of this predation by bears is probably compensatory for losses of cutthroat trout and whitebark pine.

Compounding problems for the grizzlies, their quest for dietary alternatives has led them to more often contest elk carcasses with hunters during fall and scavenge or prey on livestock during summer. As a consequence, the rates at which hunters, ranchers, and managers kill grizzlies has skyrocketed in lock step with increased depredations of livestock and close encounters with hunters in the backcountry. Mothers, moreover, are losing more cubs to predatory males as they turn to eating more meat to compensate for losses of especially whitebark pine, which was historically a particularly important food for females.

Nearly all of these dynamics are, in fact, rooted in the recent but comparatively minor 0.9oC post-industrial-revolution warming of our climate, most of which has occurred since the mid-1970s.

Grizzly Bears Will Be Adversely Affected by Future Climate Change

And, grizzly bears will be affected by future climate change. Wildfires will become even more frequent and extensive. Whitebark pine will be doomed to functional extirpation. Berry-producing shrubs will be diminished—some species dramatically so. Pollinators needed for fruit-set will continue to tank. Tundra flowers that concentrate army cutworm moths in alpine talus slopes, where grizzlies currently consume them, will almost totally disappear. Drought and earlier snowmelt will continue to compromise any prospects for recovery of cutthroat trout. Elk populations will likewise be affected by evermore prolonged and severe droughts. Ad nauseam.

At the same time, species that are blithely invoked by dangerously ignorant bear biologists as the presumed replacement for food-sources we stand to lose are either unidentified, of lesser quality, or, as in the case of Gambel oak, unlikely to colonize emerging suitable habitat at a pace even close to that at which we lose extant foods. As a friend of mine put it, this factor alone guarantees that we will be living in a world of weeds 100 years from now—if not sooner.

And all of this is forecast to transpire within a blink of the eye—the next 70 to 100 years—which will be only a first installment of the consequences arising from temperatures likely to broil the Earth a mere 300 or so years from now.

And Yet More Government Inanities

I recently reread a publication from 2010 reporting on the outcome of a workshop comprised of grizzly bear biologists assembled by the (then) USFWS Grizzly Bear Recovery Coordinator, Chris Servheen, together with a functionary of the Wildlife Conservation Society, Molly Cross, to render their purported expert opinion on how climate change would affect grizzlies. I personally know all of the twelve assembled bear biologists. None were experts on climate change. Only one had studied any aspect of linkages between changes in habitats driven by climate change, and potential responses by grizzly bears or grizzly bear populations. Most were apologists for the status quo. Two were near-professional nay-sayers of the threat posed by climate change, including the USFWS Recovery Coordinator and the single biologist from Yellowstone.

There are a few worthwhile nuggets scattered throughout the report, including recognition that changes in habitat could make changes in diet that could reconfigure exposure of grizzlies to humans, with resulting effects on levels of conflict. But it is largely populated with platitudes, most prominently that grizzlies are “adaptable omnivores.” There were some evident glimmerings of intelligent life, all apparently crushed under the steamroller of political expediency and the common denominator.