135: Grizzly Bear (North American Brown bear)

Since we just talked about wolves, a large mammal that was hunted out of Colorado in the 20th century, I thought we should talk about another large mammal that suffered the same fate but that no one is asking to return: the North American brown bear, also known as the grizzly bear, which has a truly fantastic Latin name: Ursus arctos horribilis. The last sighted grizzly bear in Colorado died in 1980, and its remains are held by the Denver Museum of Nature and Science:

“In September 1979, Ed Wiseman, a Colorado hunting guide, crossed paths with a grizzly bear during an expedition near the headwaters of the Navajo River. Wiseman was attacked and mauled, but while he was down he managed to fatally wound the bear by hand using an arrow. Severely wounded, Wiseman spent a frigid night in the high country until help arrived the next day. He was airlifted by helicopter to Alamosa, where he spent the next month in the hospital recovering from his injuries. Because grizzly bears were protected by law, a seven-month investigation into the incident ensued until it was determined that Wiseman had acted in self-defense. The case was officially dropped when he passed a polygraph test in April 1980.”

Prior to that, the previous last grizzly sighting was in 1951, with the animal killed in the same area (the San Juan Mountains in the southwestern part of the state). Some people, of course, believe that grizzlies are still in the remote mountains of southwestern Colorado or are perhaps migrating down into the northern parts of the state from where they still live in Yellowstone National Park. You can easily find several people’s blogs, photos, and internet comments swearing that they have seen evidence of grizzlies in Colorado in the 21st century. While I always like to keep an open mind about these kinds of things, it seems very unlikely that grizzlies are still within the state boundaries and have somehow managed to not be credibly seen in over forty years, given that they are enormous bears whose diets consist of a lot of meat (stable isotope studies on the 1979 specimen suggest it ate around 90% meat).

I mentioned they are big – in the lower 48 states (as opposed to the larger bears in Alaska and northern Canada*), males can weigh 400-600 lbs while females weigh 250-350 lbs. Black bears – Colorado’s largest known mammal – weigh 275 lbs and 175 lbs on average. Although there is a North America-specific subspecies, grizzlies live across the northern parts of the northern hemisphere in Europe and Asia too. They once had a very wide range in the western United States:

“Prior to 1800, an estimated 50,000 grizzly bears were distributed in one large contiguous area throughout all or portions of 18 western States… Grizzly bears were probably most common in the Rocky Mountains, along the Upper Missouri River and in California.”

Of course, the arrival of Europeans in what would become the western United States led to a dramatic reduction in those numbers. From the same source:

“With the arrival of Europeans to North America, grizzly bears were seen as a threat to livestock and human safety and, therefore, an impediment to westward expansion and settlement. In the 1800s, in concert with European settlement of the American West and government-funded bounty programs which aimed at eradication, grizzly bears were shot, poisoned and trapped wherever they were found… Grizzly bears were reduced to close to 2% of their former range in the 48 contiguous states by the 1930s, with a corresponding decrease in population, approximately 125 years after first contact with European settlers. In the early 20th century, new regulations were designed to stop future extirpations. In some areas, the protections came too late. By 1975, grizzly bear populations in the 48 contiguous states had been reduced to between 700 to 800.”

Today there are close to 2000 individual grizzlies in the lower 48 states, as a result of a recovery plan for the species put in place in 1993.

Bears evolved from doglike ancestors sometime between 55 and 38 million years ago, during the Eocene. They evolved originally in Asia and some migrated to North America during the Pleistocene.

I wasn’t originally planning on writing about grizzly bears so soon, but I saw an article about them from 2021 that really intrigued me: “Convergent geographic patterns between grizzly bear population genetic structure and Indigenous language groups in coastal British Columbia, Canada” by Hensen et al. in Ecology & Society. From the abstract, “we detected spatial alignment between Indigenous language families and grizzly bear genetic groups… This spatial co-occurrence suggests that grizzly bear and human groups have been shaped by the landscape in similar ways, creating a convergence of grizzly bear genetic and human linguistic diversity.” The rest of the paper is super interesting too, including the recommendation that Indigenous management of grizzly populations makes more sense because current non-Indigenous management has divided up genetic grizzly populations based on colonial geographic units.

Grizzly bears may be gone from Colorado, but there is a song by the band Grizzly Bear called Colorado.

*Surely you are familiar with the Katmai National Park Fat Bear Week

Next time we will talk about an animal that lives in Colorado RIGHT NOW!