Grizzly bears move through landscapes the same way most people do, preferring flat trails over slopes and gentle speeds over sprints. This comes from a notable new study of grizzly bears and how their outdoor life compares to ours.
The study, which included wild and captive bears, a special treadmill, apple slices, and GPS trackers, expands our understanding of how a natural drive to conserve energy affects the behavior of animals, including ours, and effects on health and that Weight Management Might Have. The results also help explain why bears and humans cross paths so often in the wild, and provide useful reminders of wilderness planning and everyone's safety.
Biologists and other scientists in recent years have become increasingly interested in how we and other creatures find our way through our environment. And while some preliminary answers crop up about why we move and navigate this way, the results, on the whole, aren't particularly flattering.
The accumulated research suggests that we humans as a species tend to be physically lazy, with a hardwired propensity to avoid activity. For example, in a meaningful neurological study from 2018, brain scans showed that volunteers were drawn far more to images of people in chairs and hammocks than people in motion.
This seemingly innate predilection for not moving made sense to us long ago, when hunting and gathering required hard exertion and copious amounts of calories and resting under a tree didn't. Being inactive is more problematic now, with food everywhere.
To what extent we share this preference for physical ease with other species and whether these preferences affect how we and they traverse the world has remained unclear.
Cue grizzly bears, especially those who live in Washington State University's Bear Center, the country's premier grizzly bear sanctuary and research center. University biologists affiliated with the center study how animals live, eat and interact with people.
For the new study, which was recently published in the Journal of Experimental Biology, they now decided to investigate exactly how much energy grizzlies consume when they move in different ways, and how these and comparable numbers not only relate to real behavior But bears could affect us and other animals.
In the beginning, they built a stable enclosure around a treadmill that was originally built for horses. With modifications, it could tip up or down as much as 20 percent while handling the size and weight of a grizzly. At the front of the case, the scientists added a feed box with a built-in rubber glove.
Then they taught the center's nine male and female grizzly bears – most of whom have been resident at the center since birth and with names like John, Peeka, and Frank – to climb and walk on the treadmill while slicing hot dogs as a reward and accept apples.
"Grizzlies are very food-centric," says Anthony Carnahan, a doctoral student at Washington State University who led the new study.
By measuring changes in the composition of the air in the enclosure, the researchers were able to track the energy consumption of each bear at different speeds as it walked uphill and downhill. (The bears never ran on the treadmills for safety reasons.) Using this data, the researchers determined that the most efficient pace for the bears, physiologically – the one at which they used the least oxygen – was about 2.6 mph.
Finally, the scientists gathered available information about wild bear movements using GPS statistics from grizzly bears in Yellowstone National Park, as well as map data and comparable numbers from previous studies of humans and other animals migrating through natural landscapes.
When comparing the data, the scientists found that wild grizzlies, like us, seem born to be idle. The researchers expected the wild bears to move at their most efficient speed whenever possible, says Carnahan. In reality, however, their average pace driving through Yellowstone was very fast and physiologically inefficient. 1.4 miles per hour.
They also almost always took the least steep route to get anywhere, even if it required extra time. "They did a lot of side-hilling," says Carnahan.
Interestingly, these speeds and routes were similar to those used by humans when choosing routes through wild areas, the researchers found.
Overall, the results suggest that the innate urge to avoid exertion plays a bigger role in how all creatures, large and small, normally behave and navigate than we can imagine.
However, the study doesn't rule out that grizzly bears, like other bears, can move with sudden, breathtaking speed and ferocity if they choose to, Carnahan points out. "I saw a bear running across a mountain meadow in six or seven minutes than it took me all afternoon," he says.
The results also do not tell us that we humans are destined to always walk slowly and stick to the apartments, but only that it can require both mental and physical exertion and goal setting to avoid the easiest routes are not adhered to.
Finally, the study is an invigorating reminder that we share nature with large predators, which of course choose the same paths as we do. You can find useful information on safety in grizzly land on the Interagency Grizzly Bear Committee website.