For Katmai’s bears, getting fat is a right of passage. Each and every year, they gorge
themselves on a veritable feast of anything and everything they can find - mostly salmon.
The feeding frenzy is now so well known that the National Park Service dedicates an entire
week to the spectacle. Aptly named “Fat Bear Week,” the park service uses this time
to celebrate anything and everything having to do with these burly bruins.
Festivities include educational talks and livestreams, but the real draw of Fat Bear
Week...is the bracket. Yes, the bracket. Katmai’s chunksters are thrown into the virtual gauntlet,
as rangers devise a March-Madness-style tournament to determine which bear is, in fact, the fattest.
Once the bracket is set up, you, the public, can cast your vote for the bear you think
should win. The winner is chosen on the first Tuesday of October, again aptly named, “Fat
Bear Tuesday.”
The contest returns again this year, and I’ll link to it down below so you can be sure to
cast your vote for who you think is Katmai’s fattest bear.
But, why do these bears get so fat in the first place?
The simple answer is that they need to put on as much weight as possible to survive the
frigid Alaskan winter. In colder climates, most bears will do this as they prepare for
a long winter hibernation.
The more complex answer still has to do with hibernation, but it also deals with an actual
competition between bears and the importance of Katmai’s salmon rich waters in bringing
this whole spectacle together.
Let’s tackle hibernation first. Here’s a crash course in that most famous of bear
behaviors.
Contrary to popular belief, not all bears hibernate. Only in cold climates, where winter
resources are hard to come by, do bears bed down for the long nap. Hibernation is simply
a mechanism bears use to conserve energy and wait until food is abundant once again. Even
then, not all cold weather bears do this. Polar bears have been known not to hibernate
in the winter, despite the lack of food.
Also contrary to popular belief, bears don’t “sleep” for the entire hibernation period.
Instead, they go into a sort of low-energy state called torpor.
During this state, and throughout the winter, bears can lose up to one third of their body
weight, drop their body temperature, slow their heart rate, and don’t even eat or
drink. But they’re not just wasting away either. All that fat they accumulated during
the summer is burned for energy, allowing them to maintain most of their muscle mass
for when they emerge. Bears don’t even go to the bathroom during hibernation. Instead,
they’re able to repurpose their waste into proteins to further prevent muscle decay.
And, because they’re not fully “asleep” the entire time, they get up and adjust themselves
throughout the winter, kind of like your dog does when it’s trying to get comfortable.
This is thought to help them prevent pressure sores and better retain heat.
When temperatures get warmer and food becomes available once again, bears emerge from their
dens and start the long, arduous process of survival once again.
But, enough about hibernation, let’s get back to that salmon feast. It is, after all,
the main attraction of Fat Bear Week.
Now, the National Park Service may set up a competition to pit fat bears against each
other online, but there’s also an actual competition amongst bears happening out in
the salmon rich waters of Katmai National Park. And just like online, the fattest bears
are the winners, at least in some ways. On the surface, we can look at these bears gorging
on salmon as preparing to hibernate by building up enough fat reserves to survive the winter.
And, that is true. But if we step back and look at this ecosystem as a whole, we can
see hundreds of bears all doing the same thing - competing for resources. Bears that catch
more salmon grow bigger and fatter. This means they can dominate more territory, catch even
more salmon, and grow. even. fatter.
It’s a never-ending cycle of fat bears, and when winter comes around, not only will
that fat help them survive, but for male bears, it will help make them a perfect candidate
for mating in the spring. Emerging from hibernation big and strong is the perfect way to ensure
you win the sweetheart of your dreams.
Of course, lady bears get fat too. In many ways, it’s actually more important - because
they have cubs! Not only do female bears have to compete against others for food, but they
need to make sure they put on enough weight to support their cubs as well. If mama bear
hasn’t put on enough fat to provide for her cubs, a chemical signal will actually
tell her body not to develop those baby bears, ensuring the cubs aren’t born into an environment
that can’t support them. Thus, getting fat is crucial if female bears want to have happy,
healthy, and very cute, little bear cubs.
And, let’s not forget about our little bear cub friends, because they face their own set
of challenges when it comes to getting fat. After emerging from hibernation, in just their
first year of life, bear cubs are faced with the harsh reality of survival. Just like adult
bears, cubs must make sure they put on enough fat to survive the upcoming winter. But because
they’re still so young, baby bears undergo intense growth spurts, making their search
for food that much more vital. Getting fat not only helps bear cubs to simply survive,
but to grow big and strong, ensuring they have the energy and nutrients they will need
to live a full and healthy life.
And of course, this whole spectacle is impossible without the resplendent waters of Katmai National
Park and Bristol Bay. This region of Alaska is home to more grizzly bears than people,
and has one of the largest runs of sockeye salmon anywhere in the world. The two main
rivers in the watershed, the Nushagak and Kvichak, nourish this ecosystem with vital
nutrients and resources, giving rise to a wonderful array of biodiversity.
All five species of Pacific salmon can be found here: Coho, Chinook, Chum, Pink, and
the aforementioned Sockeye. In addition to the salmon, the Bristol Bay watershed is home
to 24 other species of fish, 190 species of birds, more than 40 species of terrestrial
mammals, as well as freshwater seals, walruses, right whales, and beluga whales.
In short, Katmai and its surrounding waters are a truly wild place. It’s home to an
incredible abundance of wildlife and natural resources, including those very. fat. bears.
For these bears, getting fat is how they survive. It allows them not only to endure the harsh
Alaskan winter, but to outcompete other bears, care for their cubs, and grow big and strong.
Each year, they rely on the nutrient rich waters of Bristol Bay to supply them with
a sumptuous feast of salmon. As the weather gets cooler and cooler, the bears get fatter
and fatter. And then, when winter arrives, they bed down in their dens for a nice long
nap, dreaming of spring when they can wake up and feast once again.
Don’t forget to check out the link down below to vote for who you think is Katmai’s
fattest bear. Results will be announced Tuesday, October 5th, 2021. And as always, if you want
to learn more about the world’s protected places, don’t forget to like this video
and subscribe to the channel. It helps me bring more park stories to more people. Thank
you so much for watching, goodbye.