“Fat Bear Week is a celebration of success and resilience in our healthy population of brown bears,” Park Ranger Felicia Jimenez explains in this Wired video: How Fat Bears Bulk Up To Hibernate (And Why We Love To See It).
“It is a week-long March Madness-style bracket where the public gets to vote on their favorite fat bear.”
Fat Bear Week, however, is in October; that’s after the bears have spent summer’s end and early autumn eating as much as they can and before they hibernate for the winter.
“Sockeye salmon are very nutritious food. They’re actually pretty high calorie. One sockeye salmon will contain anywhere between two to 5,000 calories. Bears in average, they might catch 10 fish per day. If they are consuming the entire fish, they’re getting anywhere between 20,000 and 50,000 calories per day.”
Those stored calories provide the energy for them to survive as they hibernate through the winter.
During hibernation, they don’t need to eat or drink, and might not pass waste at all. Instead, their breathing rate, heart rate, and metabolic rate all slow down, and their sleep is a state of deep sleep called torpor.
Though they may not sleep the entire time, the bears remain in this state until warmer spring temperatures and hunger finally motivate them to leave their dens. Wildlife Biologist Dr. Michael Saxton, who explains:
“They’ll lose between 25 and 40% of their body weight over the winter. That’s gonna be higher for females that give birth; they’re gonna be closer to the 40% range. Some of the really large males tend to be closer to 25% range.”
“One interesting thing, that fat is not only giving them energy… the catabolism of fat also provides water. So we mentioned that they’re not drinking all winter long. This is one way that their body is able to get a little bit of water since they’re losing water constantly through respiration and stuff like that; they do need to offset that somehow.”
Fat Bear Week was founded by former park ranger Mike Fitz. The event helps educate the public about brown bear life cycles and the importance of salmon to the ecosystem of the wild and successful place on Earth.
• Fat Bear Week in the Classroom at NPS.gov.
• Brooks Falls Brown Bears Live Cam at Explore.org.
• Fat Bear Week, the NPS voting site.
Watch these related videos next:
• What’s the difference between hibernation and sleep?
• Tracking hungry Alaskan grizzly bears with Phil Torres
• Visiting a bear’s winter den with bear scientist Rae Wynn-Grant