In this episode:

• The bird that smells like a fresh-baked sugar cookie

• Why preen oil is a dating profile written in chemistry, and how seabirds use the same chemical cue that's now leading albatross parents to feed their chicks plastic

• The bonus myth Danielle wants gone

• 00:35 - A Journey Across the Atlantic

• 02:27 - The Myth of Bird Smell

• 08:00 - The Role of Smell in Bird Communication

• 14:54 - The Role of Microbiomes in Odor Production

• 25:23 - The Importance of Scent in Mate Choice

  Timestamp Disclosure
  These timestamps were generated using AI and may contain errors or omissions. They are provided for accessibility and reference purposes only and may not perfectly reflect the original audio.

Dr. Danielle Whittaker (Excerpt)

And I got back to the lab and I started to open the bag to take the bird out, and I got this overwhelming fresh bakery scent. And I was like, who? Who brought cookies to the lab? And then I realized it was the bird.

Dr. Scott Taylor

In 2013, I found myself on a small cruise ship in the middle of the Atlantic Ocean, traveling from Sierra Leone, Africa, to Brazil, and ultimately to the tip of South America. Ushuaia, Argentina. If you've never been on the open ocean, let me paint you a picture. Ocean, wind, sky, sun.

Nothing else, save for the occasional seabird. But in the equatorial ocean, that was a rare occurrence. It's disorienting, to say the least. As visual organisms, humans often use landmarks.

And this is perhaps stating the obvious. There are none of those in the open ocean.

Despite what one well intentioned cruise guests thought and asked me, the equator is not a visible line on the Earth. When after several days, I finally spotted Ascension Island, I land. And soon after spotting the island, I spotted Ascension Island.

Frigate birds wheeling in the air around it. This endemic species can only be found on this island, one of the most isolated on the planet. Seabirds are fascinating.

Most have delayed reproduction, meaning they do not start breeding until they are more than 5 and sometimes even 10 years old. During the time between fledging and breeding, they wander the world's oceans.

Sometimes, in the case of various albatross species in the Southern Ocean, they circumnavigate the globe many times. Eventually, they return to the islands where they hatch to find mates and start the next generation doing this.

Getting back to their natal island requires them to navigate these vast, featureless oceans. But to seabirds, the oceans are full of landmarks that are invisible to the eyes.

In this case, the nose knows seabird navigation, though it can rely on visual landmarks, like islands relies heavily on their sense of smell. They can detect upwellings, food, and, yes, even the island that they grew up on. And birds can use their noses for much, much more than that.

Way more. But here's the thing. If you say birds can smell at a dinner party, someone will probably correct you.

That's because there's a deeply rooted myth that birds have virtually no sense of smell. And it's been repeated so confidently and for so long, most people accept it as fact. Which brings us to the topic of today's episode.

Okay, but can birds smell?

To get to the bottom of this, we'll talk with Dr. Danielle Whitaker, a scientist at Oregon State University and author of the Secret Perfume of Uncovering the Science of Avian Scent. Danielle has spent her Career studying chemical communication in birds, among other things.

And her work on a little gray bird most of us have seen at our feeders has helped overturn two centuries of scientific substance.

We'll trace the surprisingly recent history of a myth that refused to die, Explore what birds are actually broadcasting through their scent, and ask what happens when you start paying attention to a communication channel that science ignored for 200 years? Because as it turns out, every bird you've ever watched was also wearing perfume. You just couldn't tell. Stay tuned. Welcome back, everyone.

I'm really excited to have Danielle with us today to dive into the myth about birds not being able to smell and what they actually use their sense of smell for. So thanks for joining us, Danielle.

Dr. Danielle Whittaker

Sure. Thank you so much for inviting me.

Dr. Scott Taylor

Of course, most people assume birds do not have a sense of smell. Why is that such a pervasive thing.

Dr. Danielle Whittaker

That people think this myth goes back a long way? This is actually the 200 year anniversary of this myth.

Dr. Scott Taylor

Oh, man.

Dr. Danielle Whittaker

It's been quoted over and over for decades without any attribution. A while back, I tracked it down to its source. It's actually John James Audubon. Oh, really? He published a paper in 1826.

And I'm going to read you the title.

Dr. Scott Taylor

Okay.

Dr. Danielle Whittaker

Account of the Habits of the Turkey Buzzard, Particularly with the view of exploding. The opinion generally entertained of its extraordinary power of smelling.

Dr. Scott Taylor

Exploding. All right. How did he explode it? Such a weird title.

Dr. Danielle Whittaker

So you can tell from the title he had a little bit of a bias going in.

Dr. Scott Taylor

Yeah.

Dr. Danielle Whittaker

And you can also probably infer that the idea that turkey vultures use their sense of smell to find food was pretty widely accepted at the time. They could. They would be seen attracted to the scent of dead animals, for example.

But it was also known at the time that a lot of birds, particularly birds of prey, had excellent eyesight. And there was this pervasive belief that these different kinds of traits had to involve a trade off.

So you couldn't be really good at one thing without losing some kind of ability in another thing. You can think of it kind of like when you have a certain number that you can assign to different traits in Dungeons and Dragons. Right.

You have to balance them out among the different. And so he said, well, birds have a great sense of eyesight. They can't possibly also have a great sense of smell.

And so he did a series of, I think we can all agree, very poorly designed experiments to prove this. My favorite one was when he took a dead pig carcass and put it underneath a bush and waited for the vultures to show up.

And when they didn't come down and feed on the carcass, he took that as proof that they couldn't smell it.

Dr. Scott Taylor

Okay.

Dr. Danielle Whittaker

He also notes in the paper, though, that the vultures were circling overhead all day and that his dogs kept attacking the carcass. So I think there's a pretty obvious reason why they weren't coming down to feed on it.

Dr. Scott Taylor

Yeah, I rarely see vultures and dogs sharing a carcass, so I'm sure it's so funny that they were circling around. But he didn't take that as evidence that they knew there was a dead thing there. He thought they needed to come to it. That's pretty dumb.

I mean, yeah, we've learned since then that birds use their sense of smell for lots of different things. I think, like the vultures. I mean, is quite widely accepted now that vultures use their sense of smell to find rotting food.

What other examples of birds that use their sense of smell is broadly accepted versus some of the newer insights into what birds can smell and what they use that sense of smell for?

Dr. Danielle Whittaker

Yeah, great question. So this myth persisted for a long time, but there also persisted the idea that there were some exceptions to this rule, vultures being a primary one.

The other major group that was thought to be an exception were the seabirds.

So I think people are familiar with the idea that seabirds who have to navigate over large expanses of water with no visual landmarks can use their sense of smell to navigate. They also use their sense of smell to find food, since they're attracted to things like fish and squid that are feeding on phytoplankton.

And where you have large amounts of phytoplankton in the ocean, they actually give off a chemical called dimethyl sulfide, which the seabirds can detect through their smell. However, the largest class of birds in the world, of course, is passerans, or the songbirds.

There are more species in that group than any other group, and they have relatively small brains.

I'm sure we're all familiar with the term bird brain and the part of their brain that is dedicated to olfaction, the olfactory lobe, is quite small relative to the rest of their brain, and so it was widely believed that they didn't really use smell. Also, when we look at songbirds, we associate them well. They're called songbirds, for one. So they rely on elaborate songs and calls to communicate.

And many of them have flashy plumage, very pretty feathers that they use to attract each Other. And so this reliance on sight and sound made it easy for some people to discount the importance of smell in their lives.

Dr. Scott Taylor

Yeah. And that discounting the importance of smell, it's so interesting.

You know, we make inferences from the structure of a brain about what senses might be important. And in some cases, those inferences seem to hold, but in this case, it really doesn't seem to hold.

So passerines do have a sense of smell, and they use it for some really interesting things. Can you tell us a little bit about what you've learned in that realm?

Dr. Danielle Whittaker

Yeah. So I initially became interested in this topic because I was interested in how birds choose mates.

And I've really studied this in the context of the odors that birds produce that they. That give information about themselves that are then interpreted by other birds. I've looked at a substance called preen oil, or europegial oil.

It's secreted from the europeal gland, which is located just above the base of the tail. It's the only large exocrine gland that birds have typically.

And it secretes an oil that birds then put on their feathers to help protect their feathers from exposure to the environment. In some species, it helps with waterproofing, like in ducks. And we also found pretty early on that it gives off an odor.

And I was really interested in what information is present in this odor. And so I teamed up with a pair of chemists at Indiana University, Helena Soini and Mila Shnavotny.

And we actually collaborated for about a decade trying to understand what combination of these odorants were in each bird's chemical profile and how it correlated with their own biological identity, I guess. Guess you could say. So.

Among the first things we found were that different species have different chemical signatures given off by these compounds by this oil. That within a species, particularly in the breeding season, males and females are different.

That individuals have repeatable and recognizable signatures present in these odors, and that the odor changes depending on what stage of breeding the birds are in.

Dr. Scott Taylor

Oh, cool. That's all so fascinating. Okay. There's a lot I want to ask. Can we detect those differences?

Dr. Danielle Whittaker

I've spent a lot of time sniffing birds. I figured I can tell the difference between different species, but those individual differences I'm personally not able to detect.

Dr. Scott Taylor

Okay, so we can tell humans can detect some different scent between different species of birds. I'd be really curious to know which birds smell the best.

But then the fact that different individuals have different scent profiles, I mean, it makes sense in that different people have different smelling bo. Or whatever. But I don't know why it's so interesting to think about it in the context of birds.

So let's start with which birds smell the best that you've smelled.

Dr. Danielle Whittaker

My personal favorite is the brown headed cowbird. They smell like fresh baked cookies to me, like sugar cookies.

Dr. Scott Taylor

Oh, man.

Dr. Danielle Whittaker

The first time I discovered this, I was actually interested in whether or not they gave off any kind of odor at all. Brown headed cowbirds, of course, are brood parasites.

They lay their eggs in other species nests and I've always wondered how they get away with that because birds will notice if something does smell different in their nest. I did an experiment by putting preen oil from other species on their nest and it did affect their behavior. Cool.

And so I thought, well, maybe brown headed cowbirds don't give off an odor. And so I captured some. And the way that we process birds in the field is you put them in a little brown paper bag, like a lunch bag.

It helps keep them safe, it lets light and air in. And then take them back to the lab for like all the measurements and things before returning them to the site where you release them.

And I got back to the lab and I started to open the bag to take the bird out and I got the overwhelming fresh bakery scent. And I was like, who brought cookies to the lab? And then I realized it was the bird.

And so I've since found that most birds that I've interacted with that are from the blackbird family that cowbirds are in actually do have kind of a sweet, very pleasant scent.

Dr. Scott Taylor

Oh, that's so cool. Yeah. We did an episode on brood parasitism a few weeks ago and we took down the idea that brown headed cowbirds should be disliked or maligned.

And so here's another reason to think they're very cool birds. They smell like fresh baked sugar cookies.

So if you ever get the chance with the correct permits, smell one that's so interesting to these, these individual differences, then what is the evidence that mates.

Dr. Danielle Whittaker

Can detect that people, including myself, have done a number of what we call mate choice experiments where you give birds a choice between, say if it's a male bird, you give them a choice between two females or vice versa, trying to understand what characteristics they're looking for in a mate. The problem with these experiments is you're not necessarily testing what you think you're testing there. This is not a natural situation.

They're not actually looking to mate. They're being watched in a little cage,.

Dr. Scott Taylor

Not the most natural setting for copulation. And Dating and all of that.

Dr. Danielle Whittaker

Yeah, exactly. So it's a little bit tough.

Instead of trying to come at this a different angle, one study I did looked at which birds had the most reproductive success in that season and whether that correlated with. With the odor that they gave off.

Now, that doesn't necessarily tell you if that was important in attracting them to each other, but it could tell you something about the biology of the birds that were successful there.

And so I did find a correlation with certain types of compounds and their prenoil, showing that birds who had the most surviving offspring in that year had the highest amount of certain kinds of compounds.

Dr. Scott Taylor

Oh, cool.

Dr. Danielle Whittaker

What I think is probably going on is that when birds are choosing a mate, they're, look, taking in all the information and trying to find indicators. Maybe not. Well, probably not consciously, but there's indicators of health or some kind of other, like immune function or something like that.

We have found that a lot of these odors are correlated with testosterone levels and are likely correlated with other steroid hormones like estradiol and progesterone, because especially in females, they correlate very tightly with ovulation when the female lays an egg. So that might be one aspect of the information they're looking for.

Dr. Scott Taylor

Okay. Which would maybe help with coordination or when a male really knows it's important to mate, guard, and all of those things.

Oh, that's so interesting. And I guess your work has also connected smell to the microbiome, right? I don't think that's a connection people would necessarily make.

I mean, people probably didn't know that birds have just really one major external gland which is very different than humans, which have them all over our bodies. We sweat all over the place.

Can you talk a little bit more about this potential link between the microbiome and smell and what that might mean for how we think about bird communication?

Dr. Danielle Whittaker

Yeah. So interestingly, most of the smells that we produce ourselves, that we consider our own body odor, is not produced by our own biology.

So you mentioned sweat. What we know of as armpit odor is not produced by our sweat. If you take human sweat that is sterile, it has no odor.

That odor is produced by all the microbiome that. All the. All the microbes that live in your armpit, that live in your sweat glands. And so this is common to all animals.

And I hadn't really thought about that when I first started. I was trying. People would ask me, what is the biochemical pathway to producing these odors? I didn't have even a hypothesis at that point.

And Then I met someone who would become my collaborator, Kevin Tice, who had studied hyena scent pouches for his dissertation and I think his postdoc as well.

And so hyenas, they scent mark very prolifically and they have this scent pouch that's located near the anus and it contains this yellowish green paste that is just full of microbes. And the microbes are actually what is producing the odors that the hyena are smelling from each other when they sniff those scent marks.

And so Kevin asked me, do you know anything about the microbiome of the urapygeal gland? And that just kind of blew my mind right there. I said, no, let's collaborate.

Dr. Scott Taylor

Yeah.

Dr. Danielle Whittaker

And so we started.

I would take swabs from the preying glands of a lot of different birds, and then he would do microbiome sequencing where you sequence a particular gene in your whole sample. And then you can computationally assign those sequences to different species of microbes. And of course, they have a very rich and diverse microbiome.

There's a lot of microscopic things living in those glands feeding off of that pren oil. And so we narrowed it down to look for known odor producing microbes. We found quite a few of those.

And then we did one more set of experiments where we actually. Well, actually two more sets of experiments. One, we injected antibiotics directly into preen glands and looked at the effect on the odor.

It did knock down the microbiome and it did affect the bird's odor.

And secondly, we took preen oil and then just cultured it on petri dishes and grew microbes on there and then tested whether those microbes gave off the same odors as Junco Preen oil. Junco's being the species we were studying. And there was a very clear match. People have often asked me, like, why would you study such a boring bird?

I know it's offensive. It hurts my heart.

Dr. Scott Taylor

That is so offensive.

Dr. Danielle Whittaker

They are very elegant little birds wearing tuxedos. I love Juncos.

But also I thought they were a really interesting place to start looking at the information contained in odor because there's not a lot of sexual dimorphism between these birds, males and females. To most humans, they look pretty much the same.

We would often have to measure the amount of tail weight in their tails to be sure whether we had a male or female if they weren't fully in breeding condition.

So for your listeners who might not know, males have a bit more tail white and those outer tail feathers, and they also sometimes have longer wings than females. But other than that, they're very similar.

So if the birds are not necessarily using plumage ornaments as an attractant, I was thinking along the lines of maybe odor would be more important in the species than in a species that has, you know, flashier visual signals.

Dr. Scott Taylor

Does a bird's sense of smell work any differently than mammals? I think I would assume that sense of smell has been studied most in depth in mammals and mice and model systems.

Do we know if it compare if, like, the sense of smell in birds is comparable in terms of just the way it works to what's going on in mammals, or is there still more to do there?

Dr. Danielle Whittaker

Overall, it is basically the same system. Okay, so we have a mucous lining in our nasal passages. That's the olfactory epithelium.

Birds have the same thing lining the inside of their nasal passages, inside their beaks. That epithelium contains hundreds of different olfactory receptors.

So these are proteins that get activated when they encounter an airborne odorant that matches up with it in some way. What's different here? There's a couple of things that are different between birds and mammals.

One, looking at these receptors, if you look at the DNA sequences of these receptors and the evolutionary history of them that we can infer from these sequences, birds have actually evolved a whole different class of olfactory receptors. They don't match up very well with the same ones that mammals have. They're separated into alpha, beta, et cetera.

It's actually, I think the gamma group in birds has really exploded. It's hard to draw parallels between what exactly those receptors are doing.

It's also just notoriously difficult in any species, including humans, to understand how those receptors actually map to odorants. That's been a long field of study that I think is finally starting to make some progress.

I saw some pretty interesting papers in the last couple of years. The other major difference between birds and mammals is birds completely lack something called a vomeronasal organ. Interestingly, so do humans.

But almost all other mammals have this. So if you've ever seen a dog or a cat sniff each other's butts.

Dr. Scott Taylor

Yeah, my dog, you know, they're not, first thing every dog.

Dr. Danielle Whittaker

Exactly. And they're not, like, leaning in delicately from a respectful distance to get a sniff. They're actually getting their nose up in there.

And the reason for that and the reason why they have these wet noses is that they're actually detecting compounds that are not airborne, but that are actually suspended in liquid.

And they're not using their nasal olfactory receptors for this, they're using something called a vomeronasal organ, and it's located in the palate of the mouth. A lot of things that we think of as pheromones in mammals anyway are these kinds of compounds. They're not being detected through inhaling air.

Humans and our very close primate relatives don't have a functioning bomb or nasal organ. We're kind of unique in the mammalian world that way. And birds lack it entirely.

Which might be another reason why it was thought that odor wasn't very important to them.

Dr. Scott Taylor

Yeah, that's so fascinating. I guess I knew about the vomeronasal organ. I didn't really fully understand how it works.

So now thank you for shedding light on my dog's very aggressive butt sniffing that he does every walk.

Dr. Danielle Whittaker

Okay.

So one of the earlier studies on seabirds and their use of smell beyond the context of navigation and foraging was looking at how used it in a social context. Francesco Bonadonna, who's a French researcher, was studying blue petrels.

They live in big colonies and they spend the entire day looking for food over the ocean. And then they come back at night in the dark, and they actually build their nests in burrows.

And so you've got thousands of birds on an island with all these identical little burrows. It's actually their sense of smell that helps guide them to the correct one. They know what their nest smells like, they know what their mate smells.

These researchers did this really cool experiment where they would capture a bird and this would be a known bird, they would know which one was its burrow. And they made this little contraption where they had one arm going to that bird's own nest and the other arm going to a different nest.

And then they put the bird in a little box that connected these two arms and bird always knew which one was its own nest just by the scent alone, which I'm not sure I could find my own house by smell.

Dr. Scott Taylor

I know I could not. I think I would know if I was in my own house by the sense of smell, perhaps. But even that, like, it can change so much.

I feel like my grandma's house for some reason had a very distinct smell. She was not a hoarder by any means, but I don't know, the house smelled a certain way. She baked a lot, so maybe it was.

Yeah, brown headed cowbird vibes. But that's cool. Yeah.

One thing I wanted to talk about, it came up a little bit earlier, this dimethyl sulfide scent with a Lot of seabirds using that to detect upwellings in food. There's an interesting conservation story there, too, I believe, where plastics get colonized by microbes that then release the same smell.

Dr. Danielle Whittaker

Right.

Dr. Scott Taylor

Is that something you've read about?

Dr. Danielle Whittaker

I was not aware of that. It doesn't surprise me, though. Plastics are terrible.

Dr. Scott Taylor

Yeah. I mean, so, yeah, plastics are terrible. Microplastics are awful.

But a lot of albatross feed their chicks plastic objects, and it doesn't make any sense because it doesn't look like food, like a lighter or a. Literally like a toothbrush or whatever. You'd expect that a sea bird wouldn't be like, oh, that's squid.

But apparently when the plastics get colonized by these microbes, which we were just talking about, you know, microbes are releasing these scents in preen glands as well. They release the same scent as actual food. And so the albatross might actually think they're feeding their chicks real food.

Dr. Danielle Whittaker

That's fascinating and horrifying.

Dr. Scott Taylor

Right? I know. I mean, it explains this insane pattern of. Of chicks.

And for folks listening, the albatross chicks obviously can't digest any of this plastic, but it fills up their gut and they can't pass it, and then they end up just starving to death. And you get these carcasses with dead baby albatross that have a gut full of plastic, which is horrific.

But until I think that dimethyl sulfide finding. Dimethyl sulfide finding. It's a mouthful. It didn't make sense that they would be doing that.

But, yeah, if they're relying so much on their sense of smell, like we've been talking about, it makes a lot more sense and is disturbing. Yeah, yeah, that's a dark one, but important to put out there. But can you. I guess, like, it'd be fun to talk more about your work.

Like, when you were. When you started, what was something you ended up finding that you didn't anticipate or.

Or was there a moment that you were like, oh, man, this really is a really exciting direction of research to be pursuing.

Dr. Danielle Whittaker

So when I first got the idea that scent might be important in mate choice, this was when.

So my chemistry collaborators and another member of the lab had looked at whether there was a difference in the amount of odorants that Junco prenoil produced when they were in breeding condition versus when they were not in breeding condition. The reason they were studying that this is because there's this species of bird called the red knot. It's a shorebird.

And a different researcher had found that they changed the components of their preen oil when they were nesting. And this chemical change made their nest harder to detect.

And they did some really cool studies using a dog that was trained to go look for their nests and he couldn't detect them when they were in this breeding condition. Juncos nest on the ground. They don't have very well hidden nests. They're.

And they were very, very susceptible to predators, Especially things like chipmunks and snakes. And so they were interested in seeing, well, maybe they're trying to do the same thing as the shorebirds.

Maybe they're trying to camouflage the scent of their nests. And what they found was the exact opposite. Birds in non breeding condition produced almost nothing in terms of odor.

And birds in breeding condition produced a ton of odor. And so I immediately said, wow, this must be some kind of matrize signal.

And, and like many bird researchers, my first thought was males must be using this to attract females. And we tried a lot of different things. We did find a difference in males and females, but males weren't.

Females really weren't that interested in male odors in experimental behavior experiments.

And males were actually more interested in male odor than female odor, which turned out to be because it is actually correlated with aggressive responses.

Dr. Scott Taylor

Ah, cool.

Dr. Danielle Whittaker

But over time, I started to notice that females produced larger amounts of these compounds than males in the breeding season. I started to take this insight and look at other species that other people had studied and started to see a consistent pattern.

I teamed up with a friend and collaborator of mine, Julie Hagelin, who studied this before me. She actually looked at crested aucklets. It's one of the first studies of, of seabird olfaction.

And we did this review of everything we could possibly find.

And we found that in most species in the breeding season, females either produce more diverse compounds in their odor or greater amounts of compounds, like more intense smells than males. So it really kind of makes you stop and think about your own bias. Like, oh, females are just the choosers.

Males are the ones that are out there showing, showing off. And females are just these, just selecting. But they're actually quite involved in communicating as well.

And it could be communicating that they're in breeding condition. It could be communicating that they have, you know, good health, a good immune system, therefore I would be a good mother to your offspring.

I don't know, there's all kinds of things that could be there, you know, And I'd always thought of myself as someone who didn't have that kind of bias in my behavioral research. But it's a little bit of a shock to see that. That I had immediately fallen into that trap.

Dr. Scott Taylor

It's amazing how easy it is. I mean, based on, like, what we learn going through university and as graduate students. Even if you are trying. Yeah.

To come at things in an unbiased way, there's just this whole world of training that we've had that kind of reinforces some of those biases, and it's hard to get yourself out of them, but it's amazing when you do. And you can be like, oh, man.

One, recognize that the bias exists, but two, you can push past it and then provide all this really cool new information, which is similar with respect to the importance of female bird song. One of our earliest episodes, the bs, was that female birds don't sing. They do, and it matters.

And here we have female birds producing a lot of scent that probably matters a lot for mate choice and all of these things. Back to the crested auklets. Have you ever smelt one?

Dr. Danielle Whittaker

I've never had the pleasure of interacting with a Crestedocolate.

Dr. Scott Taylor

Oh, man, me neither. But I want to.

Dr. Danielle Whittaker

I really want to.

Dr. Scott Taylor

For our listeners. They smell. And you can correct me if I'm wrong, but I've been told they smell like tangerines.

Dr. Danielle Whittaker

That's correct.

Dr. Scott Taylor

Oh, my gosh. And they're so cool looking. Can you imagine being in a colony of seabirds that just smell like tangerines? That would be.

Dr. Danielle Whittaker

That would be great.

Dr. Scott Taylor

That would be great. The booby colonies I used to work in definitely did not smell like tangerines. Neither did any individual booby. Oh, man.

All right, we've reached the part of the show that we call that's BS or that's Bird Stuff, where we give our guests an opportunity to debunk a myth that ruffles their feathers. So, Danielle, what do you want to call BS on?

Dr. Danielle Whittaker

Well, as I was researching, you know, this myth that birds had no sense of smell, and it was dating back to the 19th century, there was another parallel myth that was coming up at the same time, and it's closely related, and it really bugs me. It's not about birds, though. It's about humans.

Dr. Scott Taylor

Yeah, go for it.

Dr. Danielle Whittaker

So we also tend to think that humans don't have a very good sense of smell, and this dates back to the same time period when Audubon was claiming that birds didn't have a sense of smell. And it comes down to the same belief in this trade off.

So, Paul Broca, for whom an area of the brain is named Broca's, area, which is involved in language processing. That's not relevant here.

But he was studying the human brain, and he noticed that the olfactory lobe was much smaller in humans than it is in other mammals. But the forebrain, where all of our thinking is done, is much larger. And he basically concluded that.

He also noted that humans aren't led by their smell. They're not. I can't remember the phrase he used, like odor directed. Like if a dog smells something, he'll go after. Right.

But we are not compelled by the odors that we detect. And so he said, no, we gave up our sense of smell in exchange for free will. What? What? Yes.

Dr. Scott Taylor

That's insane.

Dr. Danielle Whittaker

It is. But this myth has continued to persist.

You'll still find people referencing the idea that humans don't really have a very good sense of smell compared to other mammals. But there's been some really fun studies where they've compared, like in a competition between humans and dogs.

My favorite was when they blindfolded volunteers and had them track the scent of chocolate that they had dragged through the grass. And then they compared. They blindfolded them, they covered up their hand, they covered up all their other senses.

Basically, they could really only use their smell.

And then they compared, like, their scent finding behaviors and the path they took and their accuracy to a dog that was doing the same test with a pheasant they had dragged through the grass. And it was remarkably similar.

Dr. Scott Taylor

Really. I mean, I do sometimes feel compelled by my sense of smell.

Like, if I'm in a grocery store and I smell a bouquet of freesia, which are my favorite smelling flower, I will buy that. I don't care how much money it is. That's not even in a food context. That's just a scent memory context for me. But that's a great one. So funny that.

Sorry.

Dr. Danielle Whittaker

If I'm at the Safeway at 4pm, that's when they put out the fresh baked loaves of French bread. I'm guaranteed to go home with a loaf of bread that day.

Dr. Scott Taylor

Yeah. Yeah. That's awesome. We gave it up for free will. Absolutely not. Well, thanks so much for joining us today.

I've really appreciated all of your insights, and this has been an awesome conversation. So thanks for coming to the podcast.

Dr. Danielle Whittaker

Thanks so much. I really enjoyed it.

Dr. Scott Taylor

Awesome. Birds are dinosaurs. And around here, we like our snacks. So we end each episode with a dinosaur nugget. Today's Nugget.

For 200 years, we told ourselves birds couldn't smell. One famous ornithologist, one terrible experiment and everyone just went with it.

Turns out every species of bird that's ever been properly tested can smell every single one. But they're not just smelling the world around them.

They're broadcasting that oil birds spread on their feathers carries chemical signatures that say, here's who I am, here's whether I'm ready to mate, and maybe even here's how healthy I am. It's a dating profile written in chemistry. And the kicker? Those scents are produced by bacteria living in a gland above the tail.

So the next time you watch a bird preen its feathers, just know it's not just grooming, it's low key. Putting on perfume. That's a wrap on this week's episode. Okay, but can birds smell?

We're gaining more listeners every week, so help us keep that going by sharing our show with a friend. End. We'll catch you next time. Byeee. Okay, But... Birds is hosted by Scott Taylor with production and creative by Zach Karl.

Transcript Disclosure
This transcript was generated using AI-assisted transcription and may contain errors or omissions. Please refer to the audio or video episode for the most accurate representation.

All audio, video, and images in this episode are either original to Okay, But... Birds (© Okay Media, LLC) or used under license/permission from the respective rights holders. Bird media from the Macaulay Library is used courtesy of the Cornell Lab of Ornithology as follows:

• Brown-headed Cowbird audio contributed by Wil Hershberger, ML94262

• Dark-eyed Junco audio contributed by Wil Hershberger, ML94361

• Red Knot audio contributed by Lucas DeCicco, ML516895

• Crested Auklet audio contributed by Sampath Seneviratne, ML132014

• Laysan Albatross audio contributed by Ted Miller, ML117679