The Science Pawdcast

Episode 31 Season 7: Polar Bears Leftovers, And Dog Judgments

• Jason and Kris Zackowski • Season 7 • Episode 31

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A top predator that “wastes” food and ends up feeding an entire ecosystem? That paradox sits at the heart of our latest exploration into polar bear behavior and the hidden scaffolding of the Arctic food web. We unpack new research estimating that each polar bear leaves roughly 300 kilograms of edible remains annually—amounting to millions of kilograms across the region—and why those leftovers are vital calories for Arctic foxes, ravens, gulls, snowy owls, and even wolves. By focusing on blubber for maximum energy return, polar bears inadvertently act as providers in a landscape where every calorie matters, and we trace how shrinking sea ice threatens not just bears but the scavengers who depend on their kills.

From icy shores to living rooms, we then tackle a beloved belief: can dogs judge human character? A Kyoto University study with 40 pet dogs put that idea to the test using a generous-versus-selfish setup. The result: no reliable preference for the kind human, even after direct interaction. We break down what this means for canine social cognition, why food-based tasks may miss the mark, and how ethics limit what scientists can test. Rather than a simple moral radar, dogs may rely on a complex blend of context, prior reinforcement, and human cues that are hard to capture in a two-choice experiment.

Along the way, we share field notes from polar bear country, practical insights for interpreting your dog’s behavior without overreading the wag, and a clear view of how climate change reshapes energy flows you rarely hear about. If you care about wildlife science, animal behavior, or how small choices ripple through entire systems, this one offers fresh data and useful takeaways.

Enjoy the show? Follow, share, and leave a quick review to help more curious listeners find us. Got a story or question we should cover next? Drop it in the comments and join the conversation.


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SPEAKER_01:

Hello, science enthusiasts. I'm Jason Zakowski.

SPEAKER_00:

And I'm Chris Zikoski.

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We're the pet parents of Bunsen, Beaker, Bernoulli, and Ginger.

SPEAKER_00:

The science animals on social media.

SPEAKER_01:

If you love science.

SPEAKER_00:

And you love pets.

SPEAKER_01:

You've come to the right spot. So put on your safety glasses.

SPEAKER_00:

And hold on to your tail.

SPEAKER_01:

This is the Science Podcast. Hello and welcome back to the Science Podcast. We hope you're happy and healthy out there. This is episode 31 of season seven. Chris, happy Halloween. We're recording this on Halloween.

SPEAKER_00:

It is, it's Happy Halloween.

SPEAKER_01:

With Bunsen being in a cone because of his surgery, we didn't really go all out this Halloween for costumes. And that's okay because we've got so many dog costumes already.

SPEAKER_00:

Exactly. And when Beaker was in a cone last year, we made her fries. And then Bunsen was a hot dog and Bernoulli was a hamburger. But we also are very cognizant of Bunsen's neck, and we didn't want to add any extra weight around his neck because we definitely want to keep his herniated disc healing and keep him healthy.

SPEAKER_01:

Yeah, so I did a flour thing. I saw another dog person on the internet do it where you cover your hand with flour and then you just kind of hit not hit, but you press your hand on the dog's head and you give them the white hand of Saruman. Of the dogs, they were so confused when I did it. They're just like, oh boy, I just want to be a part of it. And then they're like, What just happened? But it comes off right away, and Bernoulli was licking the flower off the other two dogs. So it was cute and relative. I think that was Beaker probably enjoyed that a lot better than wearing a costume because sometimes she's not she's all over wearing like the big elaborate costumes.

SPEAKER_00:

Yeah. And at least she didn't have to wear a cone of fries.

SPEAKER_01:

That's true. All right, let's get on with the show. This week in Science News, we're going to be talking about polar bears and how much food they waste. And then in pet science, a really interesting study out of Japan was looking at if dogs are a good judge of character. Because that's something that we always say is that I'll I don't know if I can trust you unless a dog trusts you. Have you heard that before, or something along that line?

SPEAKER_00:

Yep, I have.

SPEAKER_01:

All right, there's no time like Science Time. This week in Science News, let's talk about how much food polar bears waste. Um, and I actually knew about this. I know you you've read the article too, but I know about this because I was lucky enough to actually go to the tundra and see polar bears.

SPEAKER_00:

I know you planned a whole trip for your science department, and it was such a great time that you were able to get into the little buggy and go to where the polar bears were and see them in action.

SPEAKER_01:

Yeah, that it was no little buggy. It was actually a massive tundra buggy. What really sticks in my mind is the school buses that we loaded up in from the airport with the tour company. Every school bus had a shotgun hanging right above the driver. Not something you'd definitely see on a normal school bus, but it's because uh those shotguns are loaded with buckshot. And if the polar bears tried to get a tourist, they could scare them away with these shotguns. And I just thought it was apocalyptic. You'd see that in a zombie movie or something where somebody's attached a shotgun right beside the driver.

SPEAKER_00:

Did they talk about how often they use them, or is it just there for protection?

SPEAKER_01:

Very rarely, but it does happen. And the other thing in Church Rail, Manitoba, another fun fact before we get to the science, it's generally advised that you don't lock your door. You don't lock your door because for your cars or your house. So anybody who's being chased by a polar bear has somewhere quick to go. Isn't that funny?

SPEAKER_00:

I guess it's not really funny because if you were being chased by a polar bear, you would be very sad if all the doors were locked and then you got eaten because polar bears are fierce, not friendly. They look so cute, but you would be saying goodbye to your face and your whole entire body. No, not your whole entire body, because they actually waste a lot of the food that they eat. And we're going to talk about that in this article.

SPEAKER_01:

Right. The study was published October 28th in Oikos, and it talked about how they tracked how much wasted food a polar bear makes. So a single polar bear leaves about 300 kilograms of prey every year for other animals to eat. Collectively, that means all of the polar bears contribute to around 7.6 million kilograms of carrion across the Arctic. And this scavenged material is a super important food source for the food web that's up there. And it helps sustain all of the other ecosystems around the polar bear being the top predator. Now, Chris, why do polar bears waste so much food?

SPEAKER_00:

That's an interesting question, Jason. What they found is that polar bears mainly consume the seal blubber and they leave behind the rest of the carcass, which I found surprising. I thought bears would eat all of eat all of it, but no, polar bears really love out of it. Yeah. Polar bears mainly consume that seal blubber, and they're like, I don't need the rest of it.

SPEAKER_01:

And yeah, now the study doesn't talk about the reason why, but I know this is me interjecting with my polar bear knowledge. Um, it is just not calorically uh worth it for a polar bear to eat anything other than fat. So they only eat when they kill a seal because they go out and they hunt seal, that's why they only eat the fat. Because if they were to eat the meat, like the protein in a seal, it doesn't actually give them enough calories for how much calories it would take to digest it. So that's why they just eat the fat.

SPEAKER_00:

Wow, cost benefit of eating a whole meal versus just the fat.

SPEAKER_01:

Celery for humans.

SPEAKER_00:

Yeah, celery for humans. Exactly. Delicious. But until now, scientists actually underestimated the ecological importance of those leftovers that they leave behind. The team actually reviewed decades of scavenging records and anecdotes dating back from a long time ago, from the 1930s, and the data on seal caloric content and the polar bear feeding frequency. So they looked at that data to drive their study.

SPEAKER_01:

When it's peak hunting season, a polar bear can kill a seal every three to five days, and they mostly hunt ringed seals. So over a year, that's about a thousand kilograms of food consumed per bear, but they typically only eat 70% of the kill, leaving about 30% of the carrion. Seals are mostly blubber. So there's give or take 26,000 polar bears in the Arctic. These leftovers actually add up into millions of kilograms of food. And where does that food go?

SPEAKER_00:

The scavengers include Arctic foxes and gulls and ravens and actually even other polar bears. Occasionally, sometimes wolves or grizzly bears and also snowy owls will feed on the carrion or the remains. Now, it's interesting because many of these species actually couldn't access that kind of meat without having the polar bear's leftovers. And what when they were out in the field and watching and observing, they found that the foxes followed the polar bear tracks and they waited for the abandoned carcasses. So they waited in line.

SPEAKER_01:

Dangerous game to play.

SPEAKER_00:

Yeah, it's like going to the restaurant and waiting at your table with your fork and spoon. And the birds, they circled overhead, of course, and they created a loud commotion as they waited for their turn to feed. Feed me.

SPEAKER_01:

Now, one of the things this study brought to light was just how important polar bears are to all these other animals. And polar bear numbers are falling, they're declining due to Arctic temperature rise. And it doesn't take much of a mathematician to realize that the less polar bears, you have less of this carrion, and you start to lose all of that extra food for the predator. All of that extra food for the scavengers under the polar bear in the food web. It could possibly lead to horrific cascading effects and an ecosystem collapse if there's not enough polar bears. And that's not something I knew before.

SPEAKER_00:

It is. Another thing when we're talking about climate change is the melting sea ice. And that actually may make it harder for the scavengers to go and locate or to reach the remains of the polar bears that they leave behind.

SPEAKER_01:

Yeah, polar bears are amazing swimmers. They can swim long, long distances. But those other animals you mentioned, some of them are not that kind of amazing swimmers. In fact, one more TED talk polar polar bear factoid. Uh, polar bears are actually considered aquatic animals. Like they're considered animals that live in water more than they live on land, which is shocking. Isn't that funny?

SPEAKER_00:

It is funny. They're excellent swimmers, and I love that for them.

SPEAKER_01:

Yeah. Man, you just have to put yourself, think about those early explorers that came down through Hudson Bay. What would they have thought when they saw a polar bear for the first time?

SPEAKER_00:

They would have thought, oh man, this is the cutest little bear. I'm gonna make a beanie baby out of it. And then they were very sad when they found out how fierce they were.

SPEAKER_01:

Yeah. So there's a rhyme with bears. Have you heard the rhyme with bears before, Chris? We'll leave we'll end with that.

SPEAKER_00:

I have not, unless I have, and I don't know what you're alluding to.

SPEAKER_01:

Okay. If it's brown, lay down. If it's black, fight back. And if it's white, kiss your butt goodbye. Okay. It's not really a rhyme, but like you possibly can get out of it if you're tangled with a brown or black bear. But if if uh polar bear is coming at you, you're done. You're just toast. There's no chance.

SPEAKER_00:

Oh no.

SPEAKER_01:

All right. That's science news for this week. This weekend pet science. Let's talk about this study that might ruffle some feathers or get your hackles up. It's answering the question: can dogs judge character? I want to believe that. Do you want to believe that dogs can tell if people are good or bad?

SPEAKER_00:

I do. And I think many people believe that dogs can sense a person's character, like you said in the intro. And in they interpret the dog's friendliness as a sign of trustworthiness. And if the dog is hesitant, it's a sign of unease.

SPEAKER_01:

Yeah. And this is a very common belief. So I believe that, and I might still believe it after the study, though we're going to go through it. But the science doesn't really understand whether dogs actually form social evaluations of humans at all. We just don't know if a dog can look at a human and say think it's that person's good or bad. Now, other animals like chimpanzees can form reputations of humans. If you're a jerk to a chimpanzee beside a different chimpanzee, chimpanzee, then that other chimpanzee watches that and be like, You're a jerk. I'm not going to be around you. Uh, and then also dealing with you personally. So if you're a jerk to a chimp, that chimp is gonna remember that. Another do you know other animals can do that? That can there's another theme. Maybe ravens, like the Corvids.

SPEAKER_00:

Oh, yes.

SPEAKER_01:

Yeah, I love the one study where like these uh researchers weared Albert Einstein masks and went and just were jerks to a bunch of ravens, and then the ravens told everybody about the Albert Einstein masks, and then all of the ravens hated the Albert Einstein mask people. So there you go.

SPEAKER_00:

That sure is interesting about Einstein and the Corvids or the Ravens not liking those people for messing about. The research that we are looking at today about dogs was conducted by a research team from Kyoto University in Japan, and it was published on June 28th, 2025, in Animal Cognition. And the study itself involved 40 pet dogs of various ages, and they had a goal which was to test whether age or developmental stage affected a dog's ability to form reputations of humans, so to be able to judge you effectively.

SPEAKER_01:

And the study is actually really fun. There were two different phases. The first phase was the eavesdropping phase. So a dog watched another dog interact with two humans. One of the humans was very generous, fed the demonstrator dog, and the other human was selfish. It withheld food. And then there was direct interaction. So after observing, the dogs themselves interacted with the same two humans, and they recorded which human the dog approached first, the dog's approxim the dog's proximity to each person, and social behavior like tail waggings, jumpings, or staying close. What did they find, Chris?

SPEAKER_00:

What they found was that across all age groups, that dogs showed no consistent preference for the generous person over the selfish one. That was a surprise to me. I thought they would all love the treat lady or the treat gentleman. And their behavior towards both humans did not exceed chance levels. So that meant that any preference could have been random. And it was actually true after both indirect observation and having the direct experience with dealing with the humans. So these findings suggest that dogs may not easily form reputations of humans, at least not in the way that the methods were used in the study.

SPEAKER_01:

Yeah, and that's important. They used food, right? One person gave food lots and the other person didn't. So that was one of the interpretations of the study that the how dogs form a reputation of us is probably a lot more complex. Some of the challenges were the two-choice setup. It might have been too simple to capture subtle cognitive processes. And one of the things that I was reading is it's just food. It's not like one person was being cruel, right? Like you obviously could never test for this, um, where one person was being cruel to a dog and the other person was being kind. I still think that dogs can tell if somebody is cruel to dogs. But that's just me, and the study didn't go through that.

SPEAKER_00:

No, and that's a great thing to talk about because not all dogs are motivated by food. That might not have been something that they would be like, oh, I'm interested in you because I saw that you gave the food. I know all of our dogs are they work for food, they love food. They would run up to anybody with food. So I don't know.

SPEAKER_01:

But think of Beaker in like when we've been out and about, especially with kids. The kids don't have any food. She wants to see all the kids at once, right? So that test may not be effective because sometimes like dogs are hardwired just to like people, especially if it's a friendly dog. Bunsen really likes kind of everybody now. We're working on Bernoulli, he's getting a lot better, but beaker is like a social butterfly. So I don't know. I she would just be happy to see anybody and be oblivious to the food, I think. That's just my two cents.

SPEAKER_00:

That's true. I think so too.

SPEAKER_01:

So the conclusion of this is while humans often assume that dogs can judge people's character, based on this evidence, we're not sure how they can or if they do it all. It's probably a lot more nuanced, and perhaps it's something that studies can't really do ethically. And that's pet science for this week. That's it for this week's show. Thanks for coming back week after week to listen to the Science Podcast. And a shout out to all the top dogs. That's the top tier of our Patreon community, The Popac. You can sign up in our show notes. All right, Chris, let's hear those names that are part of the top dogs.

SPEAKER_00:

Amelia Fettig, Re Oda, Carol Haino, Jennifer Challenge, Linnea Janet, Karen Cronister, Vicky Oteiro, Christy Walker, Sarah Bram, Wendy, Diane, Mason and Luke, Helen Chin, Elizabeth Bourgeois, Marianne McNally, Katherine Jordan, Shelly Smith, Laura Stephenson, Tracy Leinbaugh, Anne Uchida, Heather Burbach, Kelly, Tracy Halbert, Ben Rather, Debbie Anderson, Sandy Brimer, Mary Rader, Bianca Hyde, Andrew Lynn, Brenda Clark, Brianne Hawes, Peggy McKeel, Holly Burge, Kathy Zirker, Susan Wagner, and Liz Button.

SPEAKER_01:

For science, empathy, and cuteness.