Roman records answer this question definitively.

The now extinct Atlas Brown Bear (9 ft/2.7m long and weighed up to 1,000 lbs/450 kg) and the Palestinian Brown bear, similar to Grizzly, (2 killed 50 young men at one go recorded circa 800 BC, II KINGS 2) were Roman Coliseum favorites. Pitted often against Tigers and African Lions.

Roman records show the Grizzly bear won 4 out of 5 times. However, the male African lion will lose often to the Tiger, but not always. Both dying was also common. (Fun Fact: up until 1800’s, Atlas bears and African lions competed for food in the wild).

Below is a close relative, smaller, SYRIAN brown bear. Still around. And NOT an easy meal for anything. One swipe from this little fella would give any cat a mortal wound in the wild.

I morally judge the Romans for their animal cruelty.

Hypocritically though, I know, given the opportunity, I would pay good money to experience seeing these epic battles with cold beers if I could time travel.

Just being honest with my own human Hypocritical will power.

A study in Siberia recorded 42 conflicts between the tiger and Grizzly in the wild. 22 Tiger 12 Grizzly 8 draws. Tiger’s are known to ambush other predators in their hunting area, knowing their terrain and habits of prey. Bears hibernating in long Siberian winters is obviously very effective.

INTRODUCING Siberian Tigers into a completely new area would be very difficult until they learnt the terrain, animal habits and fought for their own hunting area. They would absolutely lose more than win. At least at first. Even rattle snakes would kill a few.

Conclusion: Yellowstone bears would be just fine. The loss of more prey would be the biggest concern. When the Jamestown English lost against natives.

NOTE:

Please meet my pet 2555 lb BISON bull GOLIATH. Standing beside and average 1100lb female. He does NOT suffer intruders in HIS ZONE. A 500 lb black bear was found killed instantly pushed 20ft THROUGH Bison fencing. Goliath easily reaches speeds of 40 mph. Has to 18 inch swords. Lifted a 2000lb Traktor once. A tiger in Yellowstone would have better luck taking on a Honda civic.

A wise man once advised against making judgments based solely on appearances…

Despite their potentially clumsy appearance, Grizzly bears possess remarkable strength. Weighing approximately 500–900 pounds, they can effortlessly overpower humans. Additionally, their formidable claws, which can grow up to 4 inches in length, further enhance their predatory capabilities.

Regarding the Siberian tiger, it possesses a remarkably muscular build, indicative of its immense strength. With an average weight ranging from 300- 500 pounds, these formidable creatures have the potential to overpower humans. However, the Siberian tigers face a formidable challenge in the form of the Yellowstone grizzly bear population. The grizzlies surpass the tigers in terms of size, strength, and overall intimidation factor.

In conclusion, the Siberian tigers will face a challenging hunt.

Indeed, I am aware that the bear in the image is the sloth bear, while the tiger is the Bengal tiger.

Grizzly bears are entirely too strong and aggressive for even a Siberian tiger to take down. Some brown bear cubs, small, or infirm female grizzlies, wounded males, etc. may fall to ambush, but, for the most part, the two would give each other a wide berth and fight only occasionally over game kills.

(Phot from “The Guardian”)

The true competition would be between wolves and tigers as they would compete for the same game. The deer, bison and elk population would be quickly impacted — for a time — then one or the other species, tiger or wolf, would win the battle over game. However, this battle would be fought largely by hunting tactics and efficiency, not open battle. I do see a large wolf pack driving off a tiger from its kill, though.

The big losers would probably be mountain lions. In areas where the larger jaguar, still much smaller than a tiger, roams, the cougars tend to migrate away as they simply cannot compete with their larger cousins.

The population of introduced tigers would have to be fairly large, imo, to have a chance at sustainability.