Image © Roger Hayden - all rights reserved
Wilderness: a bear necessity
The survival of rare, far ranging wildlife such as grizzly bears depends in large measure on extensive wildland habitats with relatively few people. Without large tracts of wilderness, grizzlies, wolves, and other carnivores would be referred to as they are in the rest of their former range: in the past-tense. Of all wildlife, grizzly bears are perhaps the most sensitive barometer for the health of our Northern Rockies wildlands and the ecosystems that they support.
As scientists learn about how and why species such as the grizzly bear go extinct, the need for secure habitat becomes increasingly clear—as do the reasons for expanding the current system of protected wildlands. Wilderness protects bears from contact and conflict with people, and provides secure habitat for them to forage, den and successfully reproduce.
A recent study of historical (1850 to 1950) grizzly bear extinctions has shown that grizzly bear survival is correlated with mountainous areas comprised of more than four million acres of wildlands, in chunks that are rounder rather than elongate. Taken together, these factors combined to minimize exposure of grizzly bears to people. In smaller areas, with a greater amount of edge, and with configurations of rich habitat that concentrated grizzlies near people, populations have tended to wink out.
In other words, the more wild habitat in an ecosystem, and the fewer roads and people, the better the prospects are for the grizzly bear (and other species) to survive and successfully reproduce. It should be noted that studies documenting the impacts of roads on elk and wolves show similar relationships, but the grizzly remains the most sensitive to roads of any wildlife species studied in the Northern Rockies. Maintaining wildlands not only protects grizzlies, but other fish and wildlife as well—indeed, entire ecosystems.
Of relevance to all of this is the fact that grizzlies come into the world with formidable biological strikes against them: a low reproductive rate (the slowest in North America, second only to the Musk Ox), small letter sizes (two per litter is average), and a palette similar to ours (with a nose far keener). The latter factor means that grizzlies often end up in conflicts with us simply because they often see “our” food as their food. Grizzly bear cubs also spend a long time with Mom (two to three years), which is essential for them to learn how to survive and thrive in a world full of hazards and choices. And, although male bears can disperse long distances, females are not as bold. Young females tend to set up home territories next to or within the ranges of their mothers. As a result, bears, unlike wolves, cannot easily recolonize ecosystems that they were extirpated from, especially if these areas are hundreds of miles away.
Many people ask: how much is enough wild country? Most experts say the more, the better. In ecosystems that are smaller than 4 million acres of mostly wild habitat, historical data show that grizzly bear populations tend to wink out.
Several studies have attempted to quantify the grizzly bears need for secure or wild habitat. In the South Fork of the Flathead near Glacier Park, researchers Rick Mace and Tim Manley showed that a female grizzly needs nearly 70% of its home range in a secure, wild condition. Studies in Yellowstone show slightly higher needs for secure habitat, most likely due to the drier, more open nature of the country and differences in available foods. Other analyses of Yellowstone’s bears have demonstrated that a bear needs roughly 5000-7000 acres of secure foraging habitat, and that these areas need to be linked across the landscape so that a bear can get from one to another, without a high probability of bumping into people.
How much wild habitat grizzly bears need depends in large measure on how lethal people are. Humans are the agent of death to grizzly bears, directly by killing them and indirectly by destroying wildland habitat. Their future depends on the choices that we make.