Grizzly bear

A grizzly bear near the Lamar Valley in Yellowstone National Park in Wyoming looks over its shoulder in 2012. 

Marc Cooke/Wolves of the Rockies

WEST GLACIER — Twice last year in Great Smoky Mountains National Park, black bears attacked humans.

Twice, the National Park Service killed bears that fit the profile of the two animals believed to be responsible — right size, same gender, the first and only bears present at the scenes after the attacks, and in one case, a bear with dental injuries that were consistent with a hiker’s bite wound.

Twice, they got it wrong.

As authorities on Friday continued their attempts to locate the grizzly or black bear that killed a mountain biker just outside Glacier National Park on June 29, officials with Montana Fish, Wildlife and Parks said the agency puts no bear down “until we have conclusive evidence.”

“We would hold a bear until we were comfortable we did or did not have the right bear,” said Ron Aasheim, FWP spokesman.

Even if a bear is captured from the West Glacier incident and is conclusively linked to the death of Brad Treat, it doesn’t necessarily mean the animal would be euthanized.

“The real question is whether it was an act of self-defense” on the part of the bear, Aasheim said. “It sounds like it was an unexpected close encounter, that there might have even been a collision. I don’t have final information on that, but the bottom line is that they’ll look at whether this was a predatory act on the part of the bear.”

DNA samples from the bear were collected at the scene, three miles from the west entrance to Glacier, and officials will know if they capture the right bear, Aasheim said. As of Friday afternoon, no bear had been trapped, and the possibility of trapping the one involved in the incident gets less and less likely each passing day.

No question

If a bear consumes human flesh, there is no question it will be euthanized if captured, Aasheim said.

In 2010, an adult female grizzly, accompanied by three yearlings, attacked campers sleeping in three separate tents in the Soda Butte Campground near Cooke City, just outside Yellowstone National Park.

The third attack resulted in the death of a male camper, who was partially consumed.

Even though authorities weren’t sure if it was a grizzly or black bear they were looking for — the same holds true in last week’s West Glacier incident — they trapped a female grizzly at the campground within 16 hours of the multiple attacks.

“There was no question on that one,” Aasheim said. DNA matches confirmed she was the bear who had attacked three people as they slept, killing one, and she was executed. Her yearlings were removed from the wild and sent to an unspecified zoo.

Officials at Great Smoky Mountains National Park placed some of the blame for killing the wrong bears on the length of time it took for outside labs to process DNA samples that could have provided more conclusive evidence. Montana FWP has its own wildlife laboratory in Bozeman.

“There’s pretty sophisticated protocol our biological and enforcement folks go through” to ensure the correct bear has been captured, Aasheim said.

That becomes obvious if you read an investigative team or board review report of a bear attack.


A 35-page interagency Board of Review report on the 2015 death of Lance Crosby, a seasonal employee at a medical clinic in Yellowstone National Park, offers good insight into all that goes into an investigation of a bear attack, and the decision on whether to euthanize an animal caught in the vicinity.

Crosby, who was from Billings, was killed by a grizzly bear as he hiked on Elephant Back Mountain on Aug. 6, 2015. He was less than three-tenths of a mile from the Elephant Back Trail and less than a mile from a park housing area, in a “natural off-trail corridor area” used by both humans and wildlife.

Three hours after Crosby was reported missing, a ranger searching the area spied boots protruding from a carnivore burial cache.

The ranger “immediately backed out of the area,” reported his discovery, and the trail and area were closed to the public.

“As soon as the body was found, an investigative team consisting of law enforcement rangers, bear management personnel, and medical personnel was formed,” the report says. “At this time, the search became a body recovery and cause of mortality investigation.”

The team headed for the spot where an animal had covered Crosby’s body with dirt, duff, rocks, sticks, grass and pine needles, underneath a tree. It’s similar to how grizzlies, black bears and mountain lions cache animal carcasses.

“As the team approached the body cache site, a bear cub or cubs barked (and) bawled three to four times, and an adult bear with a light brown rump and dark brown legs was observed running away from the burial cache,” the report says.


The team found a baseball cap three feet from the body, and, curiously, an old electronics vacuum tube on top of the burial cache. Outside of the clothes Crosby was wearing and sunglasses strapped around his neck, nothing else was found despite a thorough search of the vicinity — no cellphone, camera, water bottle, backpack or bear spray.

“Vacuum tubes largely disappeared from use in the 1960s after the invention of silicon transistors,” the report said. Whether this one fell out of Crosby’s pocket, or had been dug up as an animal cached the body, was never determined — but it was noted that the tube did not appear to have been buried in the dirt, or exposed to the elements, for a long period.

The body had been partially consumed. Bite wounds on the body were consistent with a bear attack. Tracks indicative of an adult female grizzly and a cub or cubs were found next to the body.

Grizzly bear hair was found on the body, in the hinge of Crosby’s sunglasses, on a bloody rock next to the body and on the cache.

Investigators measured the puncture wounds inflicted while Crosby was still alive, as indicated by bruising that occurred. They were “consistent with those of an adult female grizzly, sub-adult male grizzly, or large adult male black bear” — too small to have come from an adult grizzly, and too large to have been inflicted by a mountain lion, wolf, coyote, or adult female or sub-adult male or female black bear.

The list of suspects was narrowing.

DNA evidence

During the spring and summer of 2015, “reliable observers” had reported 43 sightings of female grizzlies with cubs within an 18.6-mile (30-kilometer) radius of the body burial cache site.

According to the report, the sightings included at least eight unique female adults accompanied by litters of one to three cubs. Additionally, 34 of them were of four “unique, individual” female adult grizzlies that had two-cub litters.

“The bear involved in the attack and consumption of Mr. Crosby’s body was likely one of these four grizzly bears,” the report said, while cautioning that there could have been other females with cubs on or near Elephant Back Mountain that had not been reported.

In addition to measuring tracks, investigators swabbed saliva from the bite wounds on the victim, and collected bear hair off the victim’s body, clothes, sunglasses, the bloody rock, and the soil of the burial cache. Nearby bear scat was also collected.

The DNA evidence, as you would suspect, is very important to confirming the correct animal, if one is successfully trapped.

“Bear tracks are not 100 percent reliable as a method for identifying individual bears,” the Yellowstone report says. “An individual bear can leave different sized track impressions” depending on whether the tracks are left in sand, fine dirt, dust, hard-packed ground, duff, wet ground, snow or mud.

“The bear’s gait and the amount of weight or pressure placed on each foot will also affect the size of the foot pad impression left on the ground,” it goes on. “In addition, there is significant overlap in track sizes between bears of the same sex and ages classes, and some overlap between bears of different sex and age classes. Also, the actual footpad measurements taken from captured bears often don’t match 100 percent with measurements” taken on the ground.

Unreliable bite

Because human skin is somewhat elastic, bite wounds also aren't 100 percent reliable.

“Any movement by the bear (pushing, pulling, shaking of the head) or by the person being bitten (pulling away) can tear or stretch the skin and change the shape and distance between canine impressions left in the skin,” the report notes. 

And again, there is “significant overlap” in bite wound impressions between bears of the same species, sex and age class, and “some overlap” between bears of different sex and age classes.

In fact, the report notes, there is even overlap in canine width distances between different species of carnivores, such as grizzlies, black bears, mountain lions and wolves.


In all, 26 potential DNA samples were collected at the scene.

Here’s one important thing to consider: 22 of them were “non-reactive,” meaning DNA was not successfully extracted. The saliva swabs didn’t work. Nor did most of the bear hair and scat samples.

But DNA was successfully extracted from seven hairs found on the bloody rock. Three of nine scat samples also provided DNA evidence.

Bear culvert traps were set near the site the day after Crosby was killed. The team used “minimal trap bait” in the hope that bears not involved in the killing would not be lured into the area by the bait scent.

The same night the trap was set, or early the next morning, a female grizzly entered the trap and was caught. On Aug. 9, a female cub was captured and on Aug. 10, a second female cub was trapped.

Cameras set up at the site indicated no other bears visited the body burial cache during that time.

Hair, blood and tissue samples were collected from the momma bear. Her DNA matched the seven hairs taken from the bloody rock that was three feet from Crosby’s body, and one of the scat samples. The other two scat samples were linked to her offspring.

The adult female was euthanized. The two cubs were taken in by the Toledo, Ohio, zoo.

This story contains information from the Associated Press.