The Science of Birds - Bird Beaks: The Right Tool for the Job

Episode Date: November 10, 2023

This episode—which is Number 86—is all about bird beaks.This will be an overview of beak anatomy, function, evolution, and diversity.The head of every bird on Earth is adorned with a beak. A bill. And to the delight of us all, those beaks come in a wild variety of shapes and colors. Just picture the mugs of toucans, vultures, ducks, parrots, flamingos, and pelicans.The diversity of beak shapes like these is one of the fascinating things about birds. Birds use their beaks for all sorts of tasks. These appendages are vital tools, used for getting food, for grooming, for communication, and more. Links of Interest The Mark My Bird Project  ~~ Leave me a review using Podchaser ~~Link to this episode on the Science of Birds website Support the show

What are the most distinctive physical features of birds? Any five-year-old kid should be able to answer that question, right? Birds have wings, feathers, and beaks. The head of every bird on earth is adorned with a beak, a bill. And to the delight of us all, those beaks come in a wild variety of shapes and colors. Just picture the mugs of toucans, vultures, ducks, parrots, flamingos, and pelicans. The diversity of beak shapes like these is one of the fascinating things about birds. Yes, there are some non-avian critters out there with

beak-like structures in the vicinity of their mouth holes. Turtles have beaks, octopuses and squid have beaks, some fish have them, and a bunch of dinosaurs had them too. There are even some mammals that have beaks of a sort, you know, like the duck-billed platypus and the short-beaked echidna. But the bills of birds differ from those of all other living animals. They have a unique origin and a unique anatomical structure. Birds use their beaks for all sorts of tasks. These appendages are vital tools used for getting food, for grooming, for communication, and more. Without a beak, How could a woodpecker excavate a rotting tree to find beetle grubs? Without a beak, how could a hummingbird probe deep into a flower to suck out the sweet nectar?

Or without a beak, how could an angry Canada goose in your neighborhood park chase you around and bite you on the shin hard enough to draw blood? Hello and welcome. This is the science. of birds! I am your host, Ivan Philipson. The Science of Birds podcast is a lighthearted exploration of bird biology for lifelong learners. This episode, which is number 86, is all about bird beaks. This will be an overview of beak anatomy, function, evolution, and diversity.

My supporters on Patreon helped me choose the topic for this episode. As one perk they get for being paying supporters, my patrons get to vote in polls. For this episode, the choice was between the digestive system and bird beaks. Beaks just narrowly beat out the digestive system, 51 to 49%. Now, does that mean I'll never make a podcast episode about the avian digestive system? Yes, that's what it means. The digestive system had its chance, and it failed. I'm never going to talk about it again.

The people have spoken through the hallowed process of democracy, and with their votes they made it clear that basically nobody cares about the way that birds process food in their guts. Am I joking? Yes, I am. Because of course I'm going to do an episode on the digestive system. Of course I am. many of my patrons were surprisingly passionate about the possibility of an episode on that topic,

and I'll be excited to talk about the crop and gizzard and intestines and poop and all that good stuff. So that episode will happen, just not today. Now you've noticed probably that besides the word beak, I've been using the word bill. Beak, what's the difference? Well, Bill is the word word you should use when you're chatting with your high society friends down at the yacht club or at the opera house or similar venues. Use Bill when you want to impress your fancy friends with how educated you are and how well-versed you are in the esoteric language of science. The word beak, on the other hand, is more down to earth. It's better suited for use in places like the bowling alley, the dive bar or the parking lot at Taco Bell.

But the nice thing about the word beak is that it has pretty much just one meaning. Bill, however, is a polysemus word. It has more than one meaning. I bet you can think of three or four definitions for the word bill right now if you tried. But all silliness aside, there isn't any real difference between the words beak and bill in the world of ornithology. They're interchangeable. That said, scientists tend to use the word Bill more often in their official books and papers. So I guess Bill is the more technical option.

I've said Bill in this podcast much more often than Beak. And that's because I'm trying to impress you, my fancy friend. I want you to think I'm educated and smart. I hope it's working. All right, let's get into the real substance of this episode. It's time to talk about bills. First, let's look at the physical structure of the beak. From an engineering perspective, the beak is a streamlined structure that's both strong and

lightweight. It's better than a bony set of jaws bristling with teeth. better, that is, if you're a bird, and you need to weigh as little as possible in order to fly efficiently. The ancestors of birds, even the early flying ones, had bony jaws and teeth. The bird bill evolved over many millions of years into the unique, refined structure we see today. We'll talk more about how beaks evolved in a little bit. There are still bones at the core of the beak. It's just that they're relatively thin and lightweight. And like many other bones in the bodies of birds, some bones in the beak have become fused over evolutionary time.

Okay, so a bird has an upper jaw and a lower jaw. The lower jaw is typically referred to as the mandible. The upper jaw, sometimes called the upper mandible, is made of several fused bones. the maxilla, the pre-maxilla, and the nasal bones. For simplicity, scientists sometimes just call the upper jaw the maxilla. It rhymes with Godzilla, and it's spelled M-A-X-I-L-L-A. The upper part of the beak is connected to the forehead of the bird, to the cranium. Where the upper beak and cranium meet, many birds have a cranio-facial hinge. The upper jaw can actually move independently from the rest of the skull because of the craniofacial hinge.

Humans can't do that. Our upper jaw is, sadly, fused to our cranium. The movement of a bird's upper jaw relative to the cranium has a special name. Cranial kinesis. Kinesis, spelled K-I-N-E-S-I-S, has the same root as the word kinetic. kinetic. If you see a bird showing off its superpower of cranial kinesis, you'll see that its upper beak lifts slightly. Being able to flap their jaws like this, to move both jaws, gives birds the ability to skillfully manipulate food and other objects in their beaks. They can

use their beaks like precision instruments to pick things up and move them around. Some types of birds have an additional superpower when it comes to skull mobility. Cranes, shorebirds, ibises, and some other birds can move just the tip of the upper bill. This ability is called rinko-Kinesis. That's a tough one to spell. R-H-Y-N-C-H-O-K-I-N-E-S-I-S. R-K-K-K-K-E-S-I-S. Rinko-K-K-E-K-E-S-E. There's that kinesis part again, right, which refers to movement. birds displaying rinkokinesis can open up the tip of their bill to grab stuff. This is super helpful for birds with long, slender bills that probe around in mud or dirt, looking for worms, crabs, or whatever.

A bird like a long-billed curlew showing off its rinkokinesis ability kind of reminds me of one of those grabber tools. You know, the long metal thing with tongs at the end? The thing janitors in the airport go around picking up trash with so they don't have to bend over? And now I'm imagining a small army of long-billed curlews fanning out in an airport, picking up trash in their beaks as they march around with confidence in the food court and among the rows of seats at the gates. Wouldn't that be fantastic? One can only dream of such a world.

But anyway, back to the basic structure of bird beaks. We've talked about the bony core. As we move outward from the bone toward the surface, we encounter a couple of tissue layers. The first of these layers is criss-crossed with a network of blood vessels and nerves. This is the dermis. The next layer outward is the epidermis. These words probably sound familiar, since mammals like us humans also have tissue layers called the dermis and the epidermis. The inner part of the epitermis, the inner part of the epitermis, epidermis is made of living cells. These cells make a waxy protein called keratin, and that protein is what we see on the outer surface of a bird's bill. Keratin, as you probably know, is the same

stuff your hair and fingernails are made of. The outermost layer of the beak, the one made of keratin, is called the Ramphothica. Ramphothica, and that's spelled R-H-A-M-P-H-O-T-H-H-E-C-A. Ramphothica. Sorry for all these long, tricky words, but hey, that's science, yo. The texture of the rampothica varies a bit across different lineages of birds. Passerine birds and many others have a dry, hard ramphothica. The beaks of these birds have a texture similar to that of the horns of cows and sheep and whatnot. But some birds like ducks have rampotheca that are softer and more flexible. So their beaks are kind of rubbery to the touch. Cells in the epidermis are continually secreting new layers of keratin. So the rampothica is more or less

always growing, from the inside to the outside, just like the hair on your head is always growing. The older outer layers of keratin on the beak get worn down, sort of sanded off as a bird goes about its business of eating, foraging, and goofing around with its pals. Birds may even actively hone and sharpen their beaks by rubbing them on abrasive objects like rocks. The keratinous sheath that is the rampphothica can also change color, either as a juvenile bird transitions into adulthood or from one season to the next. Some birds like puffins and pelicans have elaborate beak structures that regrow every year during the breeding season. These structures are then shed after the breeding season. Sometimes something can go wrong for a bird and the cells of the

epidermis pump out keratin too rapidly. This is what happens with avian keratin disorder. Birds with this disease have overgrown, deformed bills. It's most commonly found in black-capped chickadees. When a chickadee has avian keratin disorder, AKD, its upper and lower beak grow way too long. The two parts twist and curve like fish hooks and end up crossing each other. This makes it very difficult or impossible for the poor bird to eat or to preen. A bird with AKD usually can't survive for very long. The disease was first discovered among chickadees in Alaska in the late 90s. But it has since spread geographically, and some other birds susceptible to AKD, we now know, include Corvids, woodpeckers, and nut hatches.

For a long time, scientists didn't know the cause of avian keratin disorder. But in the last few years, they've figured out that there's a virus that seems to be associated with AKD. The researchers who discovered the new virus named it Pisa virus, spelled P.O.E. E-C-I-V-I-R-U-S, PISA virus. The name PisaVirus is a reference to the chickadees, which all belong in the genus, peaceily. I'll include a photo of a black-capped chickadee with avian keratin disorder in the show notes for this episode on the Science of Birds' website.

It's a really sad thing to see. Poor little guys. Anyway, moving on. As I said, birds will sometimes rub their beaks on objects like rocks or treat branches. This could be for sharpening purposes, or it could just be a way to clean up after a meal. For example, let's say a hawk just finished tearing to shreds and then swallowing the flesh of an unlucky rodent. Now the hawk has blood and guts and rodent fur all over its face. This is unacceptable in polite society. Something has to be done. One option would be for the hawk to wipe its

filthy face on its feathers. After all, feathers would work nicely as a napkin. But the hawk doesn't do that. It doesn't want to get its feathers all gunked up with bloody grime. Instead, the hawk wipes its bill back and forth on its perch, which happens to be a tree branch. So the tree branch serves as the napkin. There's actually a word for this behavior that comes from the world of falconry. It's called faking. Not freaking, like, mm, this ice cream is so freaking good, but feking, spelled F-E-A-K-I-N-G. And it's not just raptors that feek. We see this behavior in many birds after they eat a messy meal of fruit or juicy bugs or whatever. When it's time to clean up, they get their

feek on. In most types of birds, the rents. The ramphitheca is pretty much one solid piece that forms a sheath around the upper beak and one piece that covers the lower beak. But the ramphothica of some types of birds is more complex in structure. Birds like ostriches, cormorants, pelicans, and all the seabirds in the order procellariaformis have what ornithologists call compound ramphothiki. The beaks of these birds are made of several distinct plates. the size and shape of which vary from species to species. If you look at a close-up photo of an albatross bill,

you can easily see that it's made up of several sections, several plates. For example, there's a plate called the Cullaminicorn that runs from the albatross's forehead, down the top and midline of the bill, almost, but not quite, to the tip. The tip has its own plate called the pre-maxillary nail. A beak with a compound ramphothica appears to be what all birds had originally. It's the ancestral condition. Scientists examining fossils from way back in the Cretaceous period found that ancient extinct

birds like hesperornis and ichthyornis had compound ramphothiki. The simple ramphothica we find in most modern birds is, therefore, something that evolved later. There are some other features of the beak we can look at. The tomium, for example, is the name for the cutting edge of the beak. In some birds, the tomium is more rounded. In others, it's truly sharp. The plural of tomium is tomia. Maybe you remember me talking about tomial teeth in a couple other podcast episodes.

Birds like falcons and shrikes have tomial teeth. These aren't real teeth. they're just pointy little projections of the beak made of keratin. They help these predatory birds sever the spinal cords of their prey. Fish-eating birds often have small serrations running along the tomia of their bills. Morganzers, which are ducks that specialize in eating slippery fish, have these serrations. Then we have scopate tomia. Scopate is spelled S-C-O-P-A-T-E.

Birds in dozens of families have tomia lined with tiny bundles of short bristles. Each bundle is like a teeny tiny brush. It seems that ornithologists don't really know why birds have these scopate tomia, but one hypothesis is that the brush-like structures improve the friction between the upper and lower beak and or between the beak and any object held in the beak. In other words, a bird with scopatomia might be able to grip its prey more easily. Most of the birds that have scopatomia eat insects or snails. The brushy bill edges in these birds might help them grip the hard shells of their prey.

The ridge that runs along the top of the bill is called the C-U-L-M-E-N. It's like the ridge line of a t-o-l-M-E-N. It's like the ridge line of a tail. tent or a roof. Scientists routinely measure the length of a bird's cullman using calipers while handling the bird during banding. The gonus, G-O-N-Y-S, is the corresponding part of the lower beak. The cullman is the ridge running along the dorsal surface of the beak, and the gonis is the ridge running along the ventral or bottom surface. Now, I know I'm hitting you with a lot of sciencey terminology. I know. But I believe in you. I believe you can take in all this information, process it in your large, pulsating brain, and become a better person because of it. And trust me,

everyone you know will agree that you're a better person when you start throwing around ornithology terms like cranial facial hinge, gonus, ramphothica, and scopatomia. You'll see. Anyway, nostrils! Let's not forget about the nostrils. The more technical word for the nose holes is neres, N-A-R-E-S. These are little oval or slit-shaped openings that connect to the respiratory system. But dig this. Some birds don't have naries. Cormorants, Gannets, and boobies have zero neres. Without any holes in their beaks, these birds have to breathe, through their open mouths. So that's right, they're mouth-breaters. This lack of naries is actually an adaptation to a diving lifestyle. If you don't have any openings in your bill, you don't have to worry about getting water in your nose

when you're swimming around. Gannets and boobies dive into the water at high speed. So if they had naries, they'd get jets of salt water blasting into their nasal cavities when they plunged into the waves. I remember that sort of thing happening to me as a kid when I jumped into the pool without plugging my naries, my nostrils. It was not a pleasant experience. I was all spluttering and splashing around as the chlorinated water burned my sensitive little sinuses.

Some other birds have a little structure over their naries called an operculum. This is a small flap that can temporarily close the opening of the nostril hole, at least in some species. Some birds have opercula to seal the naries while swimming. Other birds have opercula to keep pollen out of their nose when they're drinking nectar from flowers. Then we have the sear spelled C-E-E-R-E. I've talked a little about this in previous episodes. The sear is a waxy structure that covers the base of the upper bill. Picture the beak of an eagle, hawk, falcon, or parrot. Many of these birds have a seer,

which is where the naries are located and which is sometimes a different color than the rest of the beak. Earlier I mentioned the premaxillary nail. The premaxilla is the bone at the tip of the upper jaw. But I suppose in reality it's the premaxilla that forms the bulk of the upper beak, more so than the maxilla, that is.

Anyway, some birds have a little hook or nub at the end of the bill, at the tip of the premaxilla, and that is the nail. Ducks and geese have this on their bills. The nail seems to be useful for digging seeds or small prey animals out of the mud or for prying them off of rocks. The more hook-like nail of some birds, like pelicans or the shoe bill in Africa, is used like a claw to grab onto slippery prey animals such as frogs or fish. And with that, I guess that wraps up our little tour of the structure, the anatomy of a bird's beak.

It can be a challenge to do something like this without the benefit of looking at illustrations or photos. We tried to do it with only words and the power of imagination. I hope you were able to follow along and that it all made sense. The shapes of bills are generally the same. between males and females of the same species. But in some groups of birds, there can be some significant sexual dimorphism. Males and females in these species have beaks of different shapes and or sizes. We find dimorphism like this in some hummingbirds, wood hoopoos, woodpeckers,

and shorebirds. But the grand prize winner for having the most dramatic sexual dimorphism in beks has to be the Huia from New Zealand, hetero-loca Acuta Rostris. Sadly, this bird is extinct, having been seen for the last time in the early 1900s. Huia were large songbirds, roughly 20 inches long or 50 centimeters. They had black plumage and a long tail with a white tip. The bill was ivory-colored. Huia had fleshy orange waddles dangling from the corners of their mouths at the gape. The gape is what we call the place where the upper and lower jaws come together at the base of the bill.

The bills of male Huia were pointy and only slightly down-curved. They were relatively short at about 2.4 inches long or 6 centimeters. The female bill, on the other hand, was significantly longer. It was also thinner and much more deeply decurved. The bills of female and male huia were so different that early European naturalists didn't even realize the two sexes belonged to the same species. In 1836, the ornithologist John Gould named the female neomorpha acute erastrus and the male neomorpha crassarostris, as though they were two separate species.

Male and female hooia foraged in different ways on rotting wood. There are no woodpeckers in New Zealand, and it seems the hooia played the roles of wood and bark probing birds. The male used his thick, pointy bill to chisel away at rotting bark, to expose insects just below the surface. Unlike most birds, males had strong muscles for opening the beak. They could pry off pieces of bark by stabbing. into the surface, then opening their bills. If you listen to my last podcast episode, which was

about metal arcs, maybe you remember that this foraging technique is called gaping. During gaping, the bill works like a pair of reverse action pliers. The male hooia had specialized muscles on his head and neck adapted for gaping. The female, with her long, curvy bill, took a different approach to finding food. She could probe deeply into holes and crevices to snatch beetle larvae and other tasty critters. It's such a sad thing to know that these remarkable birds are extinct, gone forever. None of us will ever get to watch a pair of hooia hopping around on a tree trunk as they forage for their next meal. Sexual dimorphism in beak shape can be found in plenty of living species too, even if the differences aren't quite so dramatic. Some hummingbirds, for example,

display differently shaped bills between males and females. One hypothesis for these differences is that males and females in these hummingbird species forage differently, sort of like the hooia. Another possibility is that, for at least some hummingbird species, the sexual dimorphism and bill structure has to do more with fighting. For example, take the sparkling violet ear, colibri coruscans. This large hummingbird lives on forest edges in the Andes Mountains of South America. The sparkling violet ear is a territorial bird that dominates a patch of flowers, chasing off every other hummingbird that tries to come in for a sip of nectar. Males are super aggressive to other conspecific males than when we say conspecific we mean belonging to the same

species. So where does the beak dimorphism come in for the sparkling violator? Well, from a distance to the casual observer like a birder, the beaks of male and female sparkling violeteers look identical. But if you use a microscope to zoom and enhance, from this close-up perspective, you'll see that the beak tip of a male sparkling violet ear is pointy and rigid, like a tiny dagger. And it has these backward-facing serrations that look like wicked little hooks. The whole thing is like some sort of medieval torture instrument. The tip of the females' bill, however, has the more typical shape for a hummingbird. It's blunt and flexible, without any of those gnarly tooth or hook-like serrations.

So it seems that the beak of the male sparkling violet ear has, through the process of evolution, been weaponized. The male uses it to stab and rip at the flesh of his enemies. And his enemies are great in number. I've witnessed the carnage wrought by sparkling violet ears firsthand. I was recently in the Andes Mountains of Ecuador. I watched sparkling violet ears as they ceaselessly, aggressively defended their little patches of flowers or their hummingbird feeders. It was something to see. No bird was safe from the wrath of the sparkling violet ear, armed with his serrated dagger of doom. Now let's take a moment to consider the evolution of the bird beak.

I suppose I could fill an entire episode on this subject, but for now I'll keep it relatively brief. The first animals we might call birds evolved from theropod dinosaurs sometime around 165 million years ago, roughly. Archaeopteryx, one of the most famous prehistoric birds, lived around 150 million years ago. By that time, birds were well on their way to developing the ability of powered flight. But their faces had not yet morphed into the horny keratinous beaks we know and love today. No, those early birds still had long bony snouts filled with pointy teeth. So, flight evolved first and the beak came later. However, as I mentioned, the beak was most likely an adaptation related to flight because a beak is lighter than a tooth-filled snout.

The loss of teeth and development of a ramphothica happened not just once in the history of birds. Eidentialism evolved several times, independently in different bird lineages. I slipped another fun word in there. Did you notice? Edentialism. The definition of Eidentialism is the state of being edentulus. So there you go. Does that clear things up? Well, I'm sure you've already figured out that Emanuelism. Edentulus means having no teeth.

You know, edentulus, like your great-grandmother Mildred or Henrietta or whatever her name is, was. Anyway, the loss of teeth in birds and the development of a beak happened more than once. One of those lineages included the common ancestor of all living birds, and that creature was edentulous and had a beak. Besides the advantage of being lighter for flight, some researchers have offered alternative hypotheses for why teeth were lost again and again in different bird and dinosaur lineages. For example, one idea is that the loss of teeth was actually just a side effect, a side effect of natural selection for fast embryo growth in the egg.

Developing babies in the egg could bust. out of their eggs sooner if they didn't need to sit around growing a bunch of teeth. Faster embryo growth meant that less time would be needed to incubate the egg. And we can imagine how that would be an advantage for birds. So this whole thing is an interesting idea. In any case, when birds evolved wings, one trade-off was that they lost their clawed hands. Without hands, they couldn't reach out and grab stuff anymore. To make up for this loss, the beak became sort of like a hand with a single finger at the tip.

From a single species, the earliest common ancestor of all birds, evolution over millions of years has given us the glorious diversity in beak shapes we see today. There was this cool paper published in 2017 in the journal Nature. The researchers made 3D scans of thousands of bird beaks from over 2,000. species. These were made from preserved museum specimens. To quantify the shapes of the beaks, the researchers made landmarks on the 3D scans. For example, in a computer, they would mark the bill tip, the corners of the mouth at the gape, the curve of the cullman, and so on. The problem was, it was going to take forever if the researchers had to do all of the work of landmarking every 3D scan

themselves. So they had this brilliant idea. Why don't we enlist the help of regular people, non-scientist people? We can set up a website for them, ask them to log in, and start labeling 3D models of birdbeaks. They'll do all the work for free. Meanwhile, we can just go lay on the beach in Mexico and drink cocktails while these schmucks do the tedious mind-numbing work of clicking on computer images of dead bird skulls. And, hey, we can even tell them they're working as citizen scientists. That'll make them feel good, and they'll never suspect that we're taking advantage of them. Okay, so that's not how it really happened.

In truth, it was a great and perfectly honorable idea to enlist the help of citizen scientists for this work. This was crowdsourcing being used in a novel way to answer interesting questions about bird evolution. And of course, the researchers themselves did a ton of work to complete this study. The website they set up is called Mark My Bird. And it's still running, and you too can be a citizen scientist and help Mark 3D scans of birds. I'll put a link in the show notes, or you can just go to mark my bird.org. Using statistics, the researchers in the 2017 study linked the shape data from the birdbills to the positions of their respective species on the avian tree of life.

They modeled the evolutionary diversification of bill shapes across the tree, the phylogeny, and modeled how those shapes changed through time. One of the big findings of this project was that there was an initial burst in beak shape evolution that occurred between 80 and 65 million years ago. It was an adaptive radiation, as a single common ancestor rapidly diversified into a wild variety of new lineages with different beak shapes. Then, once the major beak shapes were established,

the pace of evolution slowed a bit. New lineages and species continued to evolve, of course, but the new forms weren't as dramatically different from those of their ancestors. They were just refinements of the older models. So, if we can use cars as an analogy, the initial explosion of beak evolution was like going from a Model T to muscle cars, monster trucks, SUVs, limousines, and station wagons,

all in about two years. The slower diversification of beaks over the tens of millions of years that followed was more like going from a hundred, Honda Civic from 1972 to a Honda Civic from 2015. Sure, there have been plenty of changes, but fundamentally the overall shape and design are similar. Over the last 65 million years, bird beaks have continued to evolve, giving us all the wonderful shapes we see today. So far, we've covered the physical structure of the beak and a bit about the evolution of beaks. Now, let's have a look at how beaks are used by birds.

Let's look at their functions. First and foremost is the function of feeding. The shape of a bird species bill is generally thought to be an adaptation for procuring and eating whatever food items that species eats. Depending on the species, the bill is used to catch animal prey, scavenge bits of dead stuff, or collect any number of plant products, like seeds, fruit, leaves, or nectar. Beaks are used not just for manipulating food items, but often for finding food items. Birds like kiwis, ibises, and shorebirds have sensory neurons in their bills

that help them detect invertebrate prey that they can't find. with their eyes alone. When I make a podcast episode about a bird species or about a bird family, one of the things I try to pay close attention to is the shape and function of the beak. It's fun to carefully consider the shape of a bird's bill and to learn how that shape is an adaptation for efficient feeding. For example, warblers have small pointy beaks for gleaning insects. Raptors have deeply curved, hooked bills for holding on to thrashing prey and for tearing flesh

into pieces. Ducks and spoonbills have spatula-shaped beaks for sifting small plants and invertebrates from water. Finches have cone-shaped bills for cracking open small seeds. Hummingbirds have long, thin bills for probing into flowers, parrots have powerful dexterous bills for manipulating fruit and seeds, crossbills have, well, crossed bills specialized for prying apart the scales of conifer cones to reach the nutritious seeds hidden within. Sandpipers have long bills that they use to probe into mud and sand to find invertebrate prey. I could go on and on and on. Pelicans, flamingos, vultures, avocetsets, skimmers, kingfishers, frog mouths, woodpeckers. Each of these types of birds has a distinct bill shape honed for the task of feeding in a distinct way. But feeding

isn't the only function of the beak. The beak is a surrogate hand, after all. It has many uses. Birds also use their bills in the very important task of preening. They groom their feathers to keep them clean. Feathers need to be as clean and parasite-free as possible so they can keep the bird warm, dry, and ready to fly. Nest building is another situation where the beak is essential. Birds use their bills and feet to gather material and to construct a nest, out of grass, twigs, mud, hair, spider webs, or whatever. The beak is also a tool for defense. For example, parent birds defend their nests by pecking fiercely at intruders. Other than the feet and clawing, the beak is pretty much the only weapon a bird has to defend itself.

For some birds, the best defense is a good offense. Like that agro-canada goose in the park that chases you around trying to bite your shins. It brings the fight to you. Or like the male sparkling violet ear, rudely stabbing everybody in the neighborhood with his wicked little dagger bill. There are countless examples of, birds using their beaks to defend themselves or to attack other birds. Did you know that the beak can also play a role in thermoregulation?

Some birds use their beaks to regulate their body temperature. Remember that there's a layer of blood vessels and nerves beneath the ramphothica. The more blood that flows through those vessels, the more heat that can be released from a bird's body. The best example of this comes from the Tocco-Tucan of South America, Ramfastos Tocco. This species has one of the largest bills of any bird relative to its body size. Research on the Tocco Tucan has shown that this bird uses its ginormous beak as a sort of radiator. When the toucan gets a little too hot, increased blood flow to its beak allows heat to radiate away from the body.

Okay, so far we've got the functions of feeding, preening, nest building, defense, stabbing your enemies, and thermoregulation. What else can beaks do? These wonders of nature. How about communication? Bird beaks have all sorts of uses in communication. A bird can use the beak itself to make sound for communicating with its conspecific friends. For example, I fondly remember listening to the loud bill clapping of white storks in Spain.

White storks are normally pretty much silent, but that changes during the breeding season. I enjoyed watching one stork sitting in the nest and then greeting its returning partner with loud, enthusiastic bill clapping. And, of course, the bill is used as an instrument to modify a bird's vocal sounds. The bill can modulate a bird's songs and calls. Just watch a singing bird and you'll see how it opens and closes its bill to shape the sound coming out of its mouth. Related to communication is the role a beak can play in courtship. Billing is a behavior many birds display, where mated pairs grab each other's beaks or they clatter them together. This endearing behavior is a way that the birds strengthen their bond.

The shape and color of the beak can be powerful signals used by birds in courtship and mate attraction. An interesting example comes from the Atlantic Puffin, Fratercula Arctica. This species and other puffins are well known for growing colorful ornamental plates on their Ramphothiki during the breeding season. But these festive sheaths slough off like scabs at the end of the season, revealing the smaller, dull-colored bill underneath, which persists through the winter. Male and female Atlantic puffins then regrow these orange and yellow Ramphothiki in every breeding season. During their courtship, there's plenty of billing going on. Adorable displays of puffins nuzzling each other, bill to bill. It's almost too cute to handle, honestly.

Anyway, there's more than meets the eye with these ornamental beak structures. Remember that birds can see colors in the ultraviolet end of the spectrum? Well, researchers have recently discovered that Atlantic puffin bills, during the breeding season, have luminous streaks on them that light up in UV light. The birds can see these glowing marks, but we can't. Pretty cool stuff, right? No one knows for sure, but it might be that these special UV markings on puffin beaks are used as signals in sexual communication. I started off this section talking about the function that beaks have in feeding. I have cheerfully perpetuated the commonly accepted understanding that a bird's beak shape is strongly associated with that bird's diet.

And that certainly makes a lot of sense. But scientists, being the good little skeptics that they are, some of them, anyway, have questioned this conventional wisdom. There's some research that suggests there isn't a purely one-to-one relationship between beak shape and diet. So this relationship may not be as strong as we think it is. Other kinds of pressure from natural selection may be involved in the shaping of bird beaks. In any case, birds lost their clawed hands long ago in the process of gaining the amazing ability to fly. The beak ended up evolving into a sort of multi-tool to replace the hands.

Birds use their beaks not just in feeding and foraging, but in just about every aspect of their fast-paced lives. After listening to this podcast episode, I hope you agree that there's actually a lot going on with this seemingly simple anatomical structure. A bird's beak is a complex marvel of natural engineering. And so we conclude episode 86. I hope you learned some new things about bird beaks here.

The next time you have an opportunity to see a bird up close, I invite you to pay a little extra attention to the structure of the beak. See if you can remember some of the terminology you learned with me today. I want to thank all my supporters on Patreon. Again, they're the ones that helped me choose this episode. topic. And a big shout out to my newest patrons. Harvey Ito, Paulina, Elena Mann, Cindy Salonardo, Laura Brown, Cherise Taggart, Kara Chow, Lawrence Tausch, Robin Wagner, and Trench Float. Thank you all so much. I'm honored that you deem my podcast to be worthy of your support. If you're not already,

it's easy to become a supporter. Just go check out my Patreon page. at patreon.com slash science of birds. There should also be a link at the bottom of the show notes in your podcast app. You can shoot me an email if you have something you'd like to share with me, perhaps an insightful comment, or you want to tell me which part of your anatomy has been weaponized for the purpose of vanquishing your enemies. In any case, my email address is Ivan at scienceofbirds.com.

I am kind of slow to respond sometimes, so please be patient with me. This again is episode 86. You can check out the show notes for the episode, along with some hand-selected photos of species I talked about today. Just go to the Science of Birds website, Science of Birds.com. I've also got a shop there on the website, where you can get yourself some fun science of birds, items of interest, like t-shirts, posters, and stickers. I'm planning on adding some new. products in the coming months, so stay tuned for that. All right, this is Ivan Philipson, wishing you a happy and peaceful rest of your day. Cheers.