Grizzly Bears Keep Being Spotted Across Colorado — And No One Can Explain Why

On the evening of September 23rd, 1979, the last day of archery elk season, a 46-year-old outfitter named Ed Wiseman was hunting alone above 11,000 feet in the South San Juan wilderness of southern Colorado, near the headwaters of the Navajo River, 14 miles from the nearest road. He heard movement in the brush behind him. What came out of it weighed 400 pounds. It knocked the bow out of his hands, put him on the ground, and stayed on him long enough to leave more than 80 wounds. Wiseman found one of the aluminum arrows he had sharpened that morning, gripped it, and drove it into the animal's neck twice. A later necropsy found that the first thrust had severed the jugular vein and the second had reached the heart. Then came the paperwork. State and federal investigators spent the next seven months on the case, and Wiseman submitted to two polygraph examinations and passed both. The seven months had a simple cause. According to the state of Colorado's own records, the animal Ed Wiseman killed on that ridge had not existed anywhere in Colorado since 1952. That file had been closed for 27 years. And the report Wiseman filed was not the only one in it. Those 27 years were not quiet ones. Accounts kept arriving out of the San Juan mountains across that stretch, from outfitters, from Forest Service personnel, from ranchers who had spent their working lives around large carnivores. None of it was ever confirmed. None of it was ever formally dismissed. It sits in the category agency language calls insufficient evidence, which is not the same thing as evidence of absence. Ursus arctos horribilis. The grizzly bear. The largest terrestrial carnivore in the lower 48 states, and a species Colorado struck from its own inventory in 1952, 17 years before there was a federal Endangered Species Act to protect it. The question here is not whether Colorado holds a grizzly population. It does not. No serious biologist argues otherwise, and the arithmetic of a remnant population surviving in genetic isolation for seven decades does not work. The question is narrower and considerably harder to answer with a no. Whether a single grizzly bear, arriving under its own power, could be standing in Colorado. The record is worth laying out before the geography, because the record is what keeps the question open. The hide and skull of the 1979 bear were accessioned into the collection of the She was more than 20 years old, with broken and abscessed teeth and arthritis in every joint, which is the reason a man with an arrow survived the encounter at all. The necropsy also established that she had bred, given birth, and nursed cubs at some point in her life. Those cubs were never located. Afterward, the Colorado Division of Wildlife searched the southern San Juans, found nothing, and closed the file a second time. Reports continued anyway. In 1990, a private search began under Round River Conservation Studies, driven by the author Doug Peacock and directed by the biologist Dennis Sizemore. In 1991, its field crews recovered hair from the Wemenooch Wilderness that a laboratory in Wyoming scored at an 80% probability of belonging to a grizzly. In 1995, more hair and a scat sample taken from a location marked on the map as Grizzly Knoll scored 75%. State biologists reviewed both results and concluded black bear. The last report Colorado treated as credible arrived in 2006, near Independence Pass. Officers investigated and found nothing. And Colorado Parks and Wildlife, the agency that inherited the 1952 determination, still maintains a public intake form on its website for reporting sightings of an animal it says is gone. Distance is where the assumption usually sits, so distance comes first. Public conversation places the nearest grizzly bears somewhere around Yellowstone National Park, roughly 500 miles north of the Colorado line, which is approximately where the population's core actually is. The nearest verified individual bears are a great deal closer than that. In the spring of 2020, the Wyoming Game and Fish Department verified a grizzly bear in the southern Wyoming range. In the spring of 2021, it verified another one, north of Viva Nauten Reservoir, from remote camera photographs submitted to the agency by a member of the public. Todd Graham, the department's Green River Region Wildlife Supervisor, put that location at approximately 65 miles south of the demographic monitoring area, which is the zone federal managers treat as habitat suitable for the species over the long term. Graham described the two spring records as the furthest south grizzly bears had been verified since well before recovery efforts began in the 1970s. The country there is sage and juniper north of Kemmerer, Wyoming. Two-lane highway, natural gas development, cattle grazing public allotments, and black bear range printed on every map the state produces. It is not wilderness, and a bear stood in it twice, in consecutive springs, and a camera caught it both times. From that reservoir, the Colorado state line lies a little over 100 miles away. The ground in between crosses the high desert of southwestern Wyoming and clips the northern flank of the Uinta Mountains in Utah. And it is not dead ground. Pronghorn, elk, and mule deer move through it on seasonal migrations that predate the fences. The overland trail followed the same line for the same reason the animals do, because it is the low, walkable seam between two mountain systems. It has always functioned as a corridor rather than a wall. A bear completing that walk would arrive in Moffat or Route County, in Colorado's northwest corner, and step into the park range, the Mount Zirkle wilderness, and the roadless country of the Route National Forest, which is high, wet, timbered, and about as close to Yellowstone habitat as the state gets. The San Juan Mountains, where the reports actually come from, sit another 300 miles south of there. That gap is the honest weakness in the story, and it will come back. What the northern corridor has lacked for roughly a century is a large bear standing at the top of it with a reason to walk south. Which is a question about the source population. When the grizzly bear was listed as threatened in 1975, the greater Yellowstone ecosystem held a few hundred animals, and some contemporary estimates ran lower still. By 2025, the Interagency Grizzly Bear Study team put that same population at approximately 1,055 bears. The recovery target federal and state managers negotiated for the ecosystem is between 800 and 950. The population has been running above the ceiling of that target for years. The space filled before the numbers plateaued. Managers formally declared the demographic monitoring area fully occupied in 2019. The first range-wide distribution report ever assembled for grizzly bears in the lower 48, published in December of 2025, found the species holding roughly 59,000 square miles of habitat and gaining about 4% more ground across two years, an expansion on the order of 2,250 square miles. Yellowstone was the exception inside that report, and the exception is the interesting part. Occupied range in the greater Yellowstone ecosystem contracted by about 3.5% over the same period, a loss of roughly 963 square miles. Cecily Costello of Montana Fish, Wildlife and Parks, the report's lead author, attributed the contraction to bears running out of country they can actually survive in. South and east of Yellowstone, the mountains give way to open prairie with no substantial river valleys for a bear to move down. The internal numbers show the same squeeze. In 2024, 71% of occupied Yellowstone range sat inside the core monitoring zone, while at the distribution peak in 2021, more than 40% of it had been outside that core. And in 2025, three out of every four grizzly bear deaths recorded in the Yellowstone area occurred inside the core, a slightly higher share than the long-term average. That is the honest shape of the pressure. Grizzly bears in the Yellowstone system are numerous, saturated at the center and pressing against edges that punish the animals pressing hardest. Bears in that position do not stop moving. Young males in that position move a long way, and a predictable number of them die a long way from where they were born, and both of those facts turn up in the mortality ledger every single year, which leaves one measurable question standing over a 100-mile gap. If the rest of the evidence is worth having, subscribe. What follows is the part that stops being an argument about maps and becomes an argument about exactly how far one bear can walk in one lifetime. The United States Fish and Wildlife Service publishes the figures. Female grizzlies typically establish home ranges 6-9 miles from the center of their mother's range, which makes female dispersal a slow generational process. Males average 18-26 miles out. Those are averages, and averages are not the relevant figure when the question is whether one animal did something unusual. Maximum documented male dispersal distances in the Greater Yellowstone and Northern Continental Divide ecosystems run from 42 miles to 109 miles. Females have been documented moving 50-56 miles, typically along the periphery of an expanding population, which is precisely the situation the Southern Wyoming Range describes. 109 miles is a documented figure attached to real collared animals in the same two ecosystems that produced the Viva Naughton bear. The distance from that camera to the Colorado state line sits inside it. A dispersal statistic also describes one movement, in one season, by one young animal leaving its mother. It does not describe the total ground available to a bear that routinely lives into its mid-20s. These are not the movements of an animal that pauses at a surveyed political boundary. So the barrier is not terrain because a grizzly bear can cross sage, desert, and interstate. The barrier is human. Interstate 80 runs east to west across southern Wyoming with fencing, traffic volume, and gas field infrastructure on both shoulders, directly across the route, and bears attempting that country get shot, hit, or reported. Another large carnivore has already run this route, repeatedly, and left collar data behind. In June of 2004, a radio-collared wolf was struck and killed by a vehicle on Interstate 70 near Idaho Springs, west of Denver. Her collar identified her as 293F, from the Swan Lake Pack in the northwest corner of Yellowstone National Park. She was the first wolf confirmed in Colorado since 1935. In 2009, Wolf 314F, collared in southwestern Montana, was tracked by satellite south through Yellowstone, into the Bridger-Teton National Forest, across southwestern Wyoming, through southeastern Idaho and northeastern Utah, and into Eagle County, Colorado. Roughly 450 miles from her origin in a straight line, and at least 1,000 miles walked to get there. Then, the one that ended the argument. Collared wolf FTOA4, called Jane, walked out of Wyoming into Colorado in 2019, lived alone in the north of the state for about 18 months, paired with a male designated M2101, and produced a litter in North Park. It was the first wolf litter documented in Colorado since the 1940s, and it happened before the state's voter-approved reintroduction program had released a single animal. North Park sits against the park range, in the same corner of Colorado a bear walking south would enter. Colorado did not need to reintroduce its first wolf. Its first wolves walked in, across southwestern Wyoming, through the same fences and highways and hostile ranch country. A wolf is not a physiologically exceptional traveler. It is a large, wide-ranging carnivore under population pressure, moving through unoccupied habitat in the direction of open space. A dispersing subadult male grizzly is that same description with more mass, more caution, and considerably less speed. This is the skeptic's natural objection, and it deserves a direct answer. In the years since Ed Wiseman's arrow, Colorado has produced no body, no photograph the state has accepted, no hair or scat sample its biologists have confirmed, no track cast, no carcass on a highway shoulder, and no bear shot by mistake during black bear season. The absence is real, and it is not a small thing. The absence of observation defense runs into a genuine problem here, and it should be stated at full strength. The San Juan Mountains are not unmonitored. Colorado Parks and Wildlife released more than 200 Canada lynx into the southern San Juans between 1999 and 2006, and since 2014 it has operated a systematic annual monitoring program there, pairing remote camera arrays with snow track surveys and environmental DNA collection. The state runs a functioning detection apparatus in exactly the mountains where grizzlies are reported, and in more than a decade it has never produced a grizzly bear. The answer is a question about design. That program was built around a small, snow-adapted cat, with cameras clustered in the high-elevation spruce and fir where lynx hunt snowshoe hare and track surveys that run in deep winter. Across the months, a grizzly would be denned and immobile. A transient bear crossing a drainage in September, staying wide of maintained trails and moving mostly at night, is not the animal that survey was engineered to catch, and the space involved is not ordinary space. The Wemenoosh Wilderness alone covers 499,771 acres, the largest wilderness area in Colorado, with no roads inside it and roughly 500 miles of trail. The South San Juan Wilderness adds another 158,790 acres. Ed Wiseman was 14 miles from a road when he was mauled, and reaching a telephone took two men on horseback and 10 more miles by vehicle. The absence of a photograph in a landscape that is very largely unphotographed does not by itself constitute evidence. Now the part that cuts the other way, because it is the strongest single argument against everything above. Colorado Parks and Wildlife publishes a species comparison alongside that sighting form, because the mistake is constant. Grizzly claws run 2-4 inches, light and straight, against 1-2.5 on a black bear, darker and more curved. Grizzly hips sit lower than the shoulders, and a black bear's sit higher. The grizzly muzzle is dished and concave where the black bear's is Roman-nosed and convex. The same agency estimates 17,000 to 20,000 black bears in Colorado, and in the San Juans, roughly 90% of them are some shade of brown. Cinnamon, honey, blonde and chocolate, with silvered guard hairs across the back, and a shoulder line that reads convincingly as a hump when the animal stands a certain way. Nearly every photograph submitted to Colorado Parks and Wildlife resolves into one of those bears. Not most of them, nearly all of them. The science does not assert that a grizzly bear is standing in Colorado tonight. It asserts something more precise, and in some ways more difficult to sit with. The conditions under which a grizzly bear could arrive in Colorado under its own power have never been more clearly in place than they are right now. The nearest verified bear is 100 miles from the state line, not 500. The population behind it is saturated at the core and pressing outward against edges that no longer reward the pressure. The maximum distance a young male has been recorded walking covers that gap with room left over, and another large carnivore has already made the crossing three separate times, on collar data, through the same corridor, and started a family at the far end of it. What the state has instead of an answer is a file. Closed in 1952, reopened by an arrow in 1979, closed again after seven months, two polygraph examinations, and a search that turned up nothing. And still, decades later, an intake form sitting on a government website with a checklist of claw lengths and muzzle profiles attached to it, waiting for a report nobody at the agency expects to receive. The bear on that ridge had nursed cubs at some point in her long life, in a state that certified her out of existence before she was born. Nobody ever found them. Nobody looked for very long. The headwaters of the Navajo River are still up there, above 11,000 feet, 14 miles from the nearest road, filling with snow the way they fill every October, the way they filled for 10,000 years before anyone drew a line across the map and wrote down which animals were permitted on either side of it.