How Fast Can a Bear Run?

Armed with astonishingly powerful forelegs, the brown bear, also known as grizzly, is the fastest of the eight bear species, reaching speeds of up to 35 miles per hour, according to the National Wildlife Federation. The grizzly is only slightly faster than the world's most common bear species, the American black bear.

Of course, a bear would be able to achieve such a feat only at the peak of its athleticism—not fresh out of hibernation, having lost 15% to 30% of its body weight—and only on certain soft, flat surfaces into which their long claws can sink.

In any case, bears are surprisingly fast considering their hulky physiques. Discover the traits and characteristics that make their swiftness possible, and what to do (besides run) if you encounter one in the wild.

Can Humans Outrun a Bear?

Not even the fastest known human on Earth, Usain Bolt, could outrun a determined black or grizzly bear at its top speed. The famous Jamaican sprinter achieved the fastest recorded human foot speed ever during a 2009 race in Berlin. He was clocked going an incredible 27.8 miles per hour, about 4 miles per hour faster than his average speed and more than 10 miles per hour faster than the average human's sprint. Still, that's 7 miles per hour slower than the supposed top speed of a grizzly and just over 2 miles per hour short of a black bear's.

At his record speed, Bolt may be able to outrun a lumbering polar bear or an Asiatic black bear (moon bear), which tops out at 25 miles per hour, or a panda or sloth bear, which can reportedly go 20 miles per hour. But even so, the line graphs that represent his breakneck sprints indicate that he—like any human—can only sustain his maximum pace for one to two seconds. A bear, however, can sustain speeds of 25 to 28 miles per hour for 2 miles, according to several reports from the 1930s in Yellowstone National Park (some of the only data on bear speed available to this day).

The average human, running at a comparatively sluggish 15 miles per hour, would simply not stand a chance. The good news is that bears, and most wildlife, would usually rather avoid humans than chase them. They generally only attack humans to protect their food, cubs, and space.

How Are Bears So Fast?

Despite their burly, boxy frames, flat feet, and the thick layer of fur you'd think would weigh them down, ursid species are surprisingly speedy. Grizzlies, in particular, have protruding, muscle mass-topped shoulder blades that power their forelimbs to run and dig. This mound of muscle creates a distinguishing hump on their upper backs—the best way to tell a grizzly from a black bear.

Bears also have impressive claws that can grow to be more than four inches long, which helps them find their footing on soft land but can hinder their running ability on hard surfaces like asphalt. Because their forelimbs are shorter, they're strong enough to support more weight than their back legs.

This lopsided stature has long given the impression that the animals can't run downhill, but that myth has been repeatedly debunked. A 1937 article in "Yellowstone Nature Notes" provides anecdotal evidence that a famous bear named Clubfoot was, in fact, slower going up than going down. It was "able to keep pace with a horse going downhill, but not uphill," said historian J. M. Mackenzie.

What Do You Do If You See a Bear?

Firstly, you can try to avoid bear encounters in the wild by making consistent noise while you're hiking and being diligent about proper food storage to not attract these mostly harmless creatures to your campsite. Know which bears frequent the area and how to identify them because different species will require different reactions.

For instance, if you encounter a black bear—the most common in the U.S., distinguishable by its straight-faced profile and tall, pointy ears—you should establish eye contact, make yourself big by spreading your arms, and make noise. On the contrary, making eye contact with a brown bear—distinguishable by its dished profile and prominent shoulder hump—is not advisable. Do not scream, yell, or make any alarming noises. Back up slowly, facing the bear if you can.

It's best to carry bear spray if you know you'll be in an area frequented by grizzlies. No matter which of the eight species of bear you see, don't turn your back on it, and never run—their predator instincts will prompt them to chase.