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Episode 399: Bears

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Thanks to Anbo, Murilo, Clay, and Ezra for their suggestions this week! Let’s learn about some bears!

Further reading:

Snack attack: Bears munch on ants and help plants grow

Extinct vegetarian cave bear diet mystery unravelled

Ancient brown bear genomes sheds light on Ice Age losses and survival

The sloth bear has shaggy ears and floppy lips [photo from this site]:

An absolute unit of a Kodiak bear in captivity [photo by S. Taheri – zoo, own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1118252]:

A polar bear:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’re revisiting a popular topic, bears! We’ll talk about some bears we’ve never covered before, with suggestions from Anbo, Clay, Ezra, and Murilo. We’ll even discuss a small bear mystery which has mostly been solved by science.

To start us off, Anbo wanted to learn about bears in general. We’ve had bear episodes before, but our last episode all about bears was way back in 2017, in episode 42. Some of our listeners weren’t even born back then, which makes me feel super old.

Bears live throughout much of the world today, but they evolved in North America around 38 million years ago. These ancestral bears were small, about the size of a raccoon, but they were successful. They spread into Asia via the land bridge Beringia, where they were even more successful than in North America, so successful that by around 30 million years ago, descendants of those earliest bear ancestors migrated from Asia back into North America. But it wasn’t until the Pleistocene around 2 ½ million years ago that bears really came into their own.

That’s because bears are megafauna, and megafauna evolved mainly as an adaptation to increasingly cold climates. As the ice ages advanced, a lot of animals grew larger so they could stay warm more easily. Predators also had to grow larger as their prey became larger, since if you want to hunt an animal the size of a bison or woolly rhinoceros, you’d better be pretty big and strong yourself.

Bears mostly weren’t hunting animals that big, though. Modern studies suggest that overall, bears are omnivores, not fully carnivorous. Bears eat a lot of plant material even if you don’t count the panda, which isn’t very closely related to other bears. Even when a bear does eat other animals, they’re not usually very big ones.

Let’s take Murilo’s suggestion as an example, the sloth bear. The sloth bear lives in India and is increasingly vulnerable due to habitat loss and poaching. It’s probably most closely related to the sun bear that we talked about in episode 234, which also lives in parts of South Asia. Both the sun bear and the sloth bear have long black hair and a white or yellowish V-shaped marking on the chest. The sloth bear’s hair is especially long on its neck and shoulders, like a mane, and its ears even have long hair.

The sloth bear stands around 3 feet high at the shoulder at most, or 91 cm, and a big male can be over 6 feet tall, or almost 2 meters, when he stands on his hind legs. This isn’t gigantic for bears in general, but it’s not small either. Scientists think the V-shaped marking on its chest warns tigers to leave the sloth bear alone, and tigers mostly do. If tigers think twice about attacking an animal, you know that animal has to be pretty tough.

The sloth bear has massive claws on big paws. The claws can measure 4 inches long, or 10 cm, although they’re not very sharp. The bear has an especially long muzzle but its teeth aren’t very large. Like most bears, it’s good at climbing trees and can run quite fast, and it swims well too. It even has webbed toes.

With all this in mind, what do you think the sloth bear eats? I’ll give you some more hints. It has loose, kind of flappy lips, especially the lower lip. It doesn’t have any teeth in the front of its upper jaw. It mainly uses its huge claws to dig.

If you guessed that the sloth bear eats ants, termites, and other insects, you are right! It digs into termite and ant nests and uses its long, flexible lips to slurp up as many insects as it can, giving them a quick crunch with its back teeth before swallowing them down.

Insects are actually quite nutritious, and the sloth bear isn’t the only bear that eats them. All bears snack on ants and other insects sometimes. You may have heard that bears love honey and will tear open beehives to get it, and while that’s true, the bear is mainly after the larval bees because they’re so nutritious. The honey is just, you know, dessert.

Next, Clay wanted to learn about the Kodiak bear, which may be the largest bear in the world. It’s a subspecies of brown bear and is sometimes called the Alaskan brown bear since it lives on some Alaskan islands called the Kodiak Archipelago. It’s light brown or rusty-red in color.

The Kodiak bear has been restricted to these islands for at least 10,000 years, since the end of the Pleistocene when the sea levels rose as glaciers melted. It demonstrates island gigantism, which is actually quite unusual. Because islands have limited resources, but are relatively protected from large numbers of predators, small animals are the ones that generally adapt to island life by growing larger. Animals that start off large generally adapt by growing smaller, called island dwarfism. That’s why some islands have been home to dwarf elephants but giant rodents.

In the case of the Kodiak bear, it has a source of protein that helps it grow so incredibly large, salmon. Five species of salmon spawn in the freshwater on the islands, and the bears are able to put on lots of weight to survive the harsh winter by eating as much salmon as they can catch. They also have lots of nutritious plants to eat. They actually prefer some plants to eating salmon, which makes sense when you think about it. A wild animal needs to conserve energy, and it can take a lot of energy to catch fish. It’s a lot easier to eat berries, which can’t swim away.

So how big can a Kodiak bear get? A big male can stand up to 10 feet tall on his hind legs, or 3 meters, and be 5 feet tall, or 1.5 meters, when standing on all fours. Bears kept in captivity can grow even larger. That’s much bigger than a grizzly and about the same size as the closely related polar bear, which brings us to Ezra’s suggestion.

Ezra wanted to learn about the polar bear, which lives in the Arctic and areas near the Arctic. It doesn’t live near the Antarctic, or south pole, which means polar bears don’t eat penguins, because penguins live around the Antarctic. The polar bear does eat a whole lot of other animals, though, and is the most carnivorous of all bears. It especially likes eating seals, and will also catch and kill walruses, caribou, and beluga whales. That’s right, the polar bear can actually kill an entire whale. The beluga is fairly small for a whale and relies on breathing holes in the ice, and sometimes when it comes up to breathe, there’s a polar bear waiting for it. Most of the time, though, the polar bear eats much smaller animals.

The polar bear spends a lot of its time on sea ice, and a lot of the time in the sea. It swims incredibly well and spends so much time in the water that some people consider it a marine animal. It’s certainly semi-aquatic. Its kidneys are adapted to filter excess salt out of its blood from seawater, and its small eyes are closer to the top of its head than in other bears. This helps it see above water while swimming.

The polar bear is closely related to the brown bear and will sometimes interbreed with the brown bear where their ranges overlap. The resulting hybrid bear is usually light brown in color. The polar bear is famously white, although its fur becomes yellowish as the year goes on. It sheds its winter coat in the spring and the new hair that grows in is white.

Actually, the polar bear’s fur is transparent, but it looks white because of the way it scatters light. The guard hairs are long and coarse, protecting a shorter, softer undercoat that helps keep the bear warm even on bitterly cold nights. Unlike other bears, the polar bear doesn’t hibernate, except for pregnant females.

There used to be a bear of similar size that lived in Europe and Asia during the Pleistocene and only went extinct about 24,000 years ago. The cave bear gets its name because so many of its remains have been found in caves. It may have hibernated in caves like some bears do today, or it might have used caves as shelters year-round.

Scientists think the cave bear was most closely related to brown bears and polar bears. The males were much larger than females, and a big male was as big as a Kodiak or polar bear. But this giant bear probably wasn’t too much of a problem for our ancient ancestors and Neandertal relations, because it was almost entirely vegetarian.

Scientists have studied the wear pattern on cave bear teeth and determined that it was eating a whole lot of fruit, especially berries. It probably did eat at least some meat, but it’s likely that most of it came from scavenged carcasses. The cave bear didn’t even have all the teeth that other bears have.

All this talk about huge bears brings us to a mystery. It may even be a mystery you were wondering about yourself. How did bears survive the end of the Pleistocene when so many other megafauna went extinct, from the mammoth and giant ground sloth to the dire wolf and sabertooth cat?

A team of scientists from Denmark and Japan decided to examine the genetics of ancient brown bears, to learn how individuals were related and therefore how bears migrated across the world over time. They extracted genetic material from the remains of bears that lived as much as 60,000 years ago and as recently as 3,800 years ago and compared them to each other and to bears alive today.

Scientists already knew that brown bears used to live in more parts of the world than they do today. The prevailing view was that as the climate warmed after the ice ages, the bears retreated into colder parts of the world where they were more comfortable. But the team learned something surprising from the study, which was published in January of 2024.

Brown bears that lived before the end of the Pleistocene, approximately 11,000 years ago, had much broader genetic diversity than the bears that lived more recently. That means that bears that lived as far south as Japan and Ireland during the Pleistocene didn’t move to colder parts of the world, they died out. Each population that went regionally extinct made the brown bear gene pool that much smaller.

Most likely it was a combination of luck and adaptability that allowed bears to survive the end-Pleistocene extinctions. Just think how sad it would be if I ended this episode by saying that bears went extinct 11,000 years ago. Instead, we can still go to the zoo and see all kinds of bears whenever we want to.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 042: Mystery Bears

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This week we’re going to learn about bears, including a bunch of m y s t e r y  b e a r s!

Hi! I am a panda bear!

A polar bear:

A spectacled bear:

A baby spectacled bear OMG LOOK AT THAT BABY:

The giant short-faced bear was indeed giant:

Further reading:

Shuker Nature

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

I’m in the mood for a bona fide mystery animal, and I bet you are too. So this week let’s learn about some mystery bears.

There are eight species of bears alive today that we know of: brown, polar, spectacled, sloth, sun, Asian and American black bears, and the giant panda. The other ones you may have heard of, like grizzlies, are subspecies of those eight. For a long time pandas were not considered bears at all, but more closely related to raccoons. These days they’re definitely in the bear box, but they’ve evolved in a completely different direction from other bears for some 19 million years, which is why they’re so different.

Before we get into the mysteries, let’s talk about just how different pandas are from other bears. As you probably know, the panda eats bamboo almost exclusively, unlike all other bears which are either omnivorous or, in the case of the polar bear, carnivorous. To survive on bamboo, the panda has evolved a lot of unusual adaptations. The front paws, for instance, have five toes just like all bears, and also a thumb. The thumb is actually a modified wrist bone that juts out from the base of the paw and helps the panda hold bamboo stalks as it eats the leaves.

Bamboo is not very nutritious. It’s certainly low in protein, especially considering that while the panda eats almost nothing but bamboo, it still has the digestive system of a carnivore. Special microbes in the panda’s intestines help break down the bamboo so the panda can digest it, but it takes a lot of bamboo to provide the energy a panda needs. A panda eats 20 to 30 pounds of bamboo leaves, stems, and shoots every day, or 9-14 kg, which means it also poops a whole lot. Seriously, it poops something like 40 times a day. And it still doesn’t have a lot of energy. It mostly just sits around eating and pooping. But while the panda just chews leaves all the time, it still has bear fangs and it will eat meat and eggs when it can. Researchers think that the panda only became exclusively a bamboo eater about two million years ago.

The panda lives in the mountains of China in only a few places. It used to also live in the lowlands but farming and other development drove it into more remote areas. There are about 50 pandas in captivity these days and somewhere between 1,500 and 3,000 pandas in the wild, with the population finally increasing after laws protecting pandas from poaching started to be enforced.

The people of China knew about the panda for centuries, although they were considered rare and elusive even in the olden days, but it wasn’t until 1869 that anyone from outside of China had a clue that gigantic roly-poly black and white bamboo-eating six-toed bears were real. Seriously, would you believe that? In 1869 a French missionary and naturalist bought a dead panda from some hunters, dissected it to study, and sent the skin to a zoologist friend in Paris.

So it’s possible that there are other mystery bears out there, known to the locals who don’t realize their bears are special, just waiting to be spotted by someone who knows a thing or two about bears.

In 1920 a Swedish scientist named Sten Bergman was shown the pelt of a bear by locals during an expedition to the Kamchatka Peninsula. That’s in the very eastern part of Russia on the Pacific coast and is sparsely populated. It’s mountainous with a cluster of active volcanos and it’s well known for the brown bears that live in the area. The Kamchatka brown bears are among the largest brown bear subspecies in the world, almost the size of the closely related Kodiak brown bear. When it stands on its hind legs it can be almost ten feet tall, or 3 meters. It’s mostly harmless to humans. Mostly. It hardly ever kills people. Just, you know, occasionally. The Kamchatka brown bears have long brown fur, sometimes pale brown but usually a sort of medium brown. They’re certainly not black. But the pelt that Dr. Bergman was shown was jet black and had short fur. But it was definitely a bear pelt, and the pelt was definitely enormous—much larger than a brown bear pelt. Bergman also saw a huge skull supposedly from one of the black bears, and a paw print 15” long and 10” wide, or 38 cm by 25 ½ cm.

Unfortunately none of the giant black bears have turned up since, living or dead. It’s possible that the bear was an unusually large brown bear with anomalous fur. Brown bears do have considerable variability in both the color and length of their fur, so it’s not out of the question that occasionally a brown bear is born that is actually black. It’s also possible that this black bear is actually a different species of bear, but that it’s either gone extinct or is extremely rare and only lives in far remote areas of Siberia these days.

But the Kamchatka Peninsula has another mystery bear for us to ponder. In 1987 a hunter named Rodion Sivolobov bought a giant white bear skin from locals. It looked like a big polar bear pelt, but the locals assured him it was from a very specific, very rare type of local bear.

They called it the irkuiem and described it as large but with a relatively small head, relatively short hind legs, and an unusual method of running. It supposedly runs in a sort of rocking motion, bringing both hind legs up to the forelegs, then throwing the forelegs forward together to start a new stride–more like a rabbit’s bounding run than a bear’s typical gait.

Sivolobov sent samples of the pelt to various zoologists in Russia, but they said there wasn’t much they could determine without a skull. But with DNA testing so much more advanced these days, it would be REALLY NICE if Sivolobov would get right on that and get his white bear pelt tested. If it really exists and if he’s not scared he was sold a marked-up polar bear skin with a tall tale.

The polar bear lives in the Arctic and is so closely related to the brown bear that the two species occasionally crossbreed when their range overlaps. Technically polar bears are marine mammals since they hunt seals on sea ice and spend a lot of time in the water. Sometimes a polar bear will drift for long distances on a piece of sea ice, or may swim for days, crossing hundreds of miles of ocean.

Polar bear feet are huge, around 12 inches wide or 30 cm, which helps keep the bear from sinking in the snow since its weight is more widely distributed on broad paws. Think snowshoes. Broad feet also helps it swim faster. The paw pads are bumpy so it’s less likely to slip on ice, and the claws are short and strong for digging in snow and ice. The polar bear stays warm because its body is heavily insulated with fat, plus its fur is thick with a soft undercoat that insulates so well that polar bears really are virtually invisible to heat-sensing radar. Male polar bears grow long fur on their forelegs, apparently because lady polar bears find that attractive. Unlike most other bears, polar bears don’t hibernate.

Georg Wilhelm Steller was a German naturalist who took part in explorations of Kamchatka Peninsula and other areas. He’s the guy that Steller’s sea-cow is named after and one day it’s getting its own episode. Anyway, in 1751 Steller wrote a book called, in English, Beasts of the Sea, and in it he mentions a report of a white sea-bear. He didn’t see it himself, but here’s his account, which I’ve taken from Karl Shuker’s excellent blog ShukerNature. I’ll link to it in the show notes.

Here’s the quote:

“Report, as I gather from the account of the people, has declared that the sea-bear, as it is called by the Rutheni and other people is different. They say it is an amphibious sea beast very like a bear, but very fierce, both on land and in the water. They told likewise, that in the year 1736 it had overturned a boat and torn two men to pieces; that they were very much alarmed when they heard the sound of its voice, which was like the growl of a bear, and that they fled from their chase of the otter and seals on the sea and hastened back to land. They say that it is covered with white fur; that it lives near the Kuril Islands, and is more numerous toward Japan; that here it is seldom seen. I myself do not know how far to believe this report, for no one has ever seen one, either slain or cast up dead upon the shore.”

Shuker suggests that this report may actually be of a fur seal, which is found in the area and has sometimes been called a sea-bear. Then again, fur seals aren’t white. They’re gray or brown and would appear darker in the water.

The Kuril Islands are a string of 56 volcanic islands that stretch between the northeastern tip of Hokkaido, Japan to the southern tip of Kamchatka Peninsula, a distance of about 810 miles, or 1300 km. Some of the largest islands are inhabited by brown bears, but it’s far from the Arctic. Polar bears get overheated easily in warmer areas, so a population of polar bears—or even a stray one—is unlikely that far south.

There are also stories of pure white bears in the forests of Hubei province in China. It’s always possible this is a garbled account of the panda, but maybe not.

In 1864, Inuit hunters supposedly killed a huge bear with yellowish fur. Naturalist Roderick McFarlane acquired the skin and skull and sent them to the Smithsonian, which promptly lost them. That’s the story, anyway. In fact, the Smithsonian did misplace the skin and skull for a while, but zoologist Clinton Hart Merriam found and examined them. He decided it was a new species of bear due to the skull’s odd shape and the light tan color of the fur.

Older polar bears do tend to have yellowish fur so maybe that’s all this bear was. But it might have been something else. As I mentioned earlier, polar bears and various subspecies of brown bear do sometimes crossbreed and produce fertile young. It’s rare, but it happens occasionally both in the wild and in captivity. The resulting babies show traits of both polar bears and brown bears, and tend to be pale brown or tan in color with darker brown paws. Then again, there’s a MonsterQuest episode that I haven’t actually seen where a paleontologist examines the McFarlane skull and states it’s just that of a young female brown bear.

For having only eight species, bears are remarkably widespread and vary considerably in diet and appearance. The sloth bear mostly eats insects, for instance. It lives in India and has shaggy black fur with a pale muzzle and white claws, big floppy ears, and a white V-shaped mark on the chest. It lacks upper incisors, which helps it slurp up insects.

Sloth bears are actually pretty darn awesome. Males often help raise the cubs and mothers carry their babies around on their backs. The sloth bear doesn’t hibernate, probably because it doesn’t really get cold where it lives.

The spectacled bear lives in South America. It’s the last close relative of the giant short-faced bear that went extinct about 11,000 years ago. The spectacled bear is mostly black, although some individuals may appear brown or reddish, and most but not all have lighter markings on the face and chest. Its head is much less bearlike than other bears, with a rounded face and short snout. It mostly eats plants and lives in the Andes Mountains and surrounding areas. It spends a lot of time in trees, and will even build a little platform in a tree to sleep on or store food on.

And you know what? Paddington Bear is modeled on the spectacled bear.

The spectacled bear is not especially scary. Its relative, the giant short-faced bear, was another story. It lived in North America, especially in California, and its remains have been found in the La Brea tar pits. But it also lived as far south as Mississippi. And it was huge. It was simply enormous. It stood up to 6 feet at the shoulder, or 1.8 meters, and twice that when standing on its hind legs. One website I read pointed out that regulation height for a basketball rim is ten feet, which means a giant short-faced bear could dunk the ball every time without doing anything more strenuous than standing up. It was probably an omnivore like most modern bears, but we have mastodon bones that show tooth marks from the short-faced bear.

Naturally, as with just about any extinct animal, people keep hoping they’re not really extinct and occasionally someone reports seeing a giant short-faced bear. Some cryptozoologists speculate that the Kamchatka Peninsula mystery bears may actually be short-faced bears, but since short-faced bear fossils have only been found in North America, it’s probably not likely that there would be any living in Russia. Besides, the short-faced bear would have looked very different from the brown bear, probably shaped more like a colossal spectacled bear. Locals would definitely notice the difference. Moreover, it’s not likely to live in the same area that already has a population of brown bears, since both animals would then be competing for the same resources.

Personally, while the giant short-faced bear is awesome to imagine, I’m perfectly happy with it not wandering around in the forests. Because I like to hike. And I worry enough about the relatively small and harmless American black bear as it is.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on iTunes or whatever platform you listen on. We also have a Patreon if you’d like to support us that way.

Thanks for listening!