The Dangerous Life of a Grizzly
Posted October 23, 2012
Photo courtesy of the National Park Service: Photographer unknown
It isn’t easy being a grizzly bear. Sure, they spend six months of the year sleeping and the other six months eating (and who wouldn’t LOVE that?), but the truth is that life as a grizzly – a top-of-the-food-chain predator – is filled with danger and uncertainties. There is a good chance that you will not survive the first year of life and an even greater chance that you will not live to a ripe old age—your early 20s in the wild.
For grizzlies, life begins in the dead of winter where cubs are born tiny, naked, and defenseless weighing as little as 12 ounces. (Think about that next time you’re chugging down a small latte which weighs roughly the same.)
By the time cubs are old enough to leave the den in spring, they’ve grown fur, packed on between 10 to 20 pounds, but they remain vulnerable to many dangers including larger male grizzlies that are eager to find a mate to carry their offspring. Male grizzlies are not particularly sentimental when it comes to the act of procreation and cubs are easy targets for these big boars that will kill the cubs (even their own cubs) for the chance to mate with their mothers.
And speaking of the mothers ... female grizzlies really have it rough. They need to focus all of their attention on rearing their young and protecting them from harm. She has only a few short years to help them learn how to hunt, which areas contain the best food, and which areas they must avoid at all costs. And on top of all of these threats, a new danger could prove to be the Great Bear’s undoing in our oldest national park.
High-elevation forests have experienced a catastrophic loss of trees (particularly whitebark pine trees) due to the climate-driven invasion of mountain pine beetle. Trees once mostly untouchable to the tiny invaders due to harsh winter cold snaps of way-below-zero temperatures are now sitting ducks at the top of the tree line.
The importance of whitebark pine seeds in the diet of grizzlies has long been established. The seeds from this tree have traditionally been a very important source of food for grizzlies and female grizzlies in particular have benefited from this food source for three reasons. First, the seed of whitebark pine is a fat bomb! Over 50% of the nutritional value of a whitebark pine seed is fat. And when your primary goal is adding enough fat reserves to survive the long, cold winter, huge caches of this high calorie food could decide whether or not you will bear cubs, or what condition you will find yourself in the spring—bears lose between 15-30% of their body weight during hibernation.
Second, since whitebark pine grows at high elevations (generally between 6,000 and 9,000 feet) it serves to keep grizzlies, particularly females and cubs, farther away from the dangers that exist at lower elevations like garbage, livestock, roads and people.
And, finally, whitebark pine is a less risky food to acquire for grizzlies. No killing, no risk of injury…they move through these ancient forests keying in on the chatter of small red squirrels who have conveniently cached huge middens of these seeds for their own winter food supply. For a female to rely on meat instead of these fatty, nutritious seeds would mean putting herself and her cubs in greater danger of being killed.
What is true is that grizzlies are omnivores, and, yes, there are still other foods available for grizzly bears, but the decline of whitebark pine trees (and their high-calorie seeds and remote, high-elevation location) will make it tougher for grizzly bears to make a living on the landscape in the future in and around Yellowstone.
In 2009, NRDC (in collaboration with the U.S. Forest Service and Geo Graphics), conducted the first-ever aerial assessment of the impacts of mountain pine beetle in high elevation forests in the Greater Yellowstone Ecosystem (GYE). The survey determined that 46% of whitebark pine in the ecosystem showed a high level of mortality, 36% showed a moderate amount of mortality, and 13% showed low mortality. Taken together, 82% of whitebark pine in the GYE in 2009 had been impacted by mountain pine beetle—a heartbreaking loss to not just grizzlies, but a whole host of species that rely on this keystone tree species.
But for grizzlies in particular, the loss of whitebark pine is a devastating blow. Without these seeds, grizzlies will need to roam more widely in order to feed themselves and their cubs. The real question is will people let them? Are we willing to change our own behavior to accommodate these amazing creatures? Are we willing to implement creative ways to non-lethally protect livestock from conflicts with grizzlies? Are we willing to take greater responsibility when recreating in bear country by learning how to behave in grizzly country? Are we willing to help communities in bear country devise new ways of securing trash so bears don’t become habituated to human foods?
From my perspective, the answer is obvious. They are amazing creatures that deserve our respect and our best effort. Grizzlies have their place in this wild landscape and right now they need our help. It isn’t easy being a grizzly, but with a little help and tolerance from us, they can endure. We just need to be creative, patient and determined to work together to prove that this place is big enough for the both of us!