Global warming and the grizzly bears

StoryImage( ‘/Images/Story//Auto-img-117329884826657.jpg’, ‘Photo courtesy of‘, ‘The federal government is considering taking the grizzly bear off the endangered species list. About 600 grizzlies are known to inhabit Yellowstone Park, a population that wildlife biologists consider to be stable. ‘);

Everyone has been alerted to the predicted and provable warming of the planet earth and the serious ecological consequences that will probably occur in the future. For example, as a result of melting glaciers, the oceans will rise and inundate present-day shorelines, and polar bears and other arctic animals will be endangered. Vast climatic changes will occur, and certain ecosystems will be obliterated or drastically changed.

An article in a recent issue of The New York Times concerning another effect of global warming on the fauna of the earth caught my eye as it concerned how this phenomenon will affect grizzly bears; a chain reaction involving the mountain pine beetle, the whitebark pine and the grizzly bear.

Charles Petit of The Times writes that Dr. Jesse Logan, a retired scientist with the U.S. Forest Service, is butting heads with the federal government, which is considering taking the grizzly bear off the endangered or threatened species list in the area in and around Yellowstone Park. Presently, about 600 grizzlies are known to inhabit the park and wildlife biologists consider that number to be a stable population and what the park can support. But, in national forests and other land outside of the park, grizzly populations are increasing by 4 to 7 percent each year, and they have been doing this for the past 40 years. This is the primary reason the feds say they should be removed from the endangered list in that general area.

The controversy between Logan and the government is based on what the grizzlies eat in that area. In the early spring after they have come out of hibernation, they feed on the calves of elk and bison and on other large animals that have not survived the winter. During summer and early fall, they take fish from the rivers and lakes, much to the delight of ogling tourists. They also partake of roots and berries during this period. But, as late fall and winter approaches they need to fatten up for the long hibernation period where stored fat is slowly metabolized as they sleep, so they move to higher country where the whitebark pine grows. The seeds of this pine are rich in nourishment and are relished by the bears.

The whitebark pine is a scraggly, slow-growing tree that is extremely long lived. The famed naturalist John Muir once counted the growth rings of a whitebark pine in the Sierra Nevada range in California and found it was 426 years old though the trunk of the tree measured barely 6 inches across. The wood of the whitebark is of little or no value, but it is a favorite of the mountain pine beetle, which attacks and eventually kills it when the insect encounters it. In areas around Yellowstone Park, one can observe vast stretches of dead whitebark pines. This beetle also attacks the ponderosa and lodgepole pines with equal vigor. These pines grow in mid-altitude locations as does the whitebark, but the latter also does well in higher, colder elevations.

The mountain pine beetle cannot survive in colder temperatures and was quick to take advantage of the fact that global warming, and perhaps other factors, has raised the temperature of the Rocky Mountains 2 degrees in the last 40 years. The destructive beetles have moved into regions of the high country, where previously they could not exist, and are having a field day with the whitebark pines growing there.

Logan and his many scientific colleagues believe the grizzly bears of the Yellowstone area would become endangered again and, perhaps, could not survive if the whitebark pines were eventually killed off by the invading beetles. Their thesis is the bears should remain on the endangered list to have a chance at survival if their source of food for the winter is indirectly destroyed by global warming.

The web of life existing on Mother Earth is certainly a delicate one that has evolved over eons of time, and any drastic disturbance of the web is sure to result in disastrous consequences for the flora and fauna. Changes in the temperature of the earth have occurred during its long history, but these changes, the Ice Age, for example, were brought about by natural causes. Today’s global warming, however, is being caused by man’s activities, and the many individuals who believe the earth belongs to humans to do with as they see fit. The truth of the matter is, as the wise old Indian philosopher Chief Seattle pointed out, we belong to the earth.

As I write this my indoor weather station tells me that it is 5 degrees Fahrenheit outside, and I would not be adverse to a bit of temporary global warming to beset us here in the Rock River Valley.

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

From the March 7-13, 2007, issue

Enjoy The Rock River Times? Help spread the word!