The Science of Birds - Penguins

Episode Date: September 29, 2021

This episode is all about penguins. All penguins belong to the family Spheniscidae.Penguins are among the most bizarre and specialized birds in the world. Few other birds represent such a departure from what we think of as the standard avian model. The specializations of penguins—their adaptations—serve them very well for a life of diving deep into the ocean and of surviving in extreme cold.These birds are wonderful examples of how “life finds a way”—how animals can evolve into radically different forms, adapt to incredibly harsh conditions, and still manage to look pretty darn cute.~~ Leave me a review using Podchaser ~~Links of InterestExtinct mega penguin was tallest and heaviest everMelting Antarctic Ice Causing Penguins to StarveNice illustration showing the relative sizes and appearances of every penguin species.Scientists Discover “Super-Colony” of 1.5 Million Adélie Penguins in Images From SpaceSupport the show

Penguins are among the most bizarre and specialized birds in the world. Few other birds represent such a departure from what we think of as the standard avian model. Penguins are chubby and heavy-boned. They don't fly. They don't perch in trees. Heck, it seems like they can barely walk. The specializations of penguins, their adaptations, serve them very well for a life of diving deep into the ocean and of surviving in extreme cold.

The water itself may be just above freezing. And on land, some penguin species endure temperatures as low as minus 40 degrees Fahrenheit for weeks at a time. To me, one of the most fascinating things about penguins is the long arc of their evolutionary history. Their ancestors were little theropod dinosaurs back in the Cretaceous, something like miniature velociraptors. then those guys evolved into feathered flying creatures but before long they started spending a lot more time in the sea swimming and diving and then they lost their ability to fly and went all in on the diving life those were some serious evolutionary twists and turns one of my favorite books is after man a zoology of the future the author dougal dixon uses the principles of evolution and ecology to speculate about what animal life on Earth could look like 50 million years from

now, long after humans have gone extinct. Thus the book's title, After Man. Evolution is highly unpredictable, of course, so the book isn't offering predictions, just imaginative speculations grounded firmly in science. In this future world, whales have been extinct for a long time, but nature abhors a vacuum, and it was the penguins that ended up filling the ecological niches left empty by whales. Over 50 million years, these birds became more whale-like. One of the coolest creatures in Afterman is the Vortex, Balinornis Vivipura. It's the largest animal in the world. The illustration in the book looks like a cross between a penguin and a killer whale. The vortex lives as a filter feeder cruising the southern ocean. It uses its enormous, sieve-like bill to strain tiny

krill from the water. Like a whale, this monstrous bird can't walk or survive on land, but it has evolved the ability to give birth to live young without having to lay eggs on dry ground. Such a creature isn't that far-fetched, really. Just look at the various stages of penguin evolution that have already occurred in the real world. Not to make it. mention the equally incredible evolution of whales. Anyway, penguins are rad. They're wonderful examples of how life finds a way, how animals can evolve into radically different forms, adapt to incredibly harsh conditions, and still manage to look pretty darn cute. Hello and welcome. This is the science of birds.

I am your host, Ivan Philipson. The Science of Birds podcast is a lighthearted, guided exploration of bird biology for lifelong learners. This episode is all about penguins. All penguins belong to the family, Svanicity. They're high on the list of humanity's most loved birds. Penguins get a lot of attention from us. For example, an inordinate number of movies have been made about these birds, from Academy Award-winning documentaries like March of the Penguins,

to animated movies for kids like Happy Feet and The Pebble and the Penguin. Chances are that you've seen some of these movies, and chances are you know a fun factor to about penguins. Some things we learn about penguins from pop culture are true, and others are totally bogus. But we don't need to make up anything about penguins, because there's no shortage of fascinating and very real things to learn about their anatomy and behavior. And that's what brings us to today's episode. Let's look past the Hollywood caricatures and get to know the actual birds in the penguin family. This is a big episode, so let's dive in.

Before we consider the key traits of penguins, let's listen to how award-winning British actor Benedict Cumberbatch tries to say the word penguins. You probably know Mr. Cumberbatch from his roles as Sherlock Holmes, Dr. Strange, and many others. He's super famous. Here are a few samples of him narrating a documentary. Is penguins, crested penguins, parent penguins. heading home. So why are these woodlands so attractive to penguins? Pengwings? Penguins? Say it with me, Benedict, penguins. Right, where were we? Ah, yes, key traits. I imagine we all learned to recognize

the basic shape of a penguin when we were still wearing diapers. The silhouette of a penguin is unmistakable. Its body is ovoid or egg-shaped in the extreme. It tapers at both ends, like a football or blimp. Some would describe this as spindle-shaped. But hey, kids in the 21st century, do you know what a spindle is? No, you mean you don't hand-spin wool into yarn on a regular basis? The ovoid body shape of a penguin gives the bird some excellent streamlining. It dramatically increases swimming efficiency. We say that flying birds and airplanes are aerodynamic, whereas penguins, fish, and sharks are hydrodynamic.

As far as scientists have been able to determine, penguins are among the most perfectly hydrodynamic animals on the planet. Having a chunky body like that also helps a penguin stay warm. It gives the bird a low surface area to volume ratio, compared to, say, your average songbird. In other words, a penguin has a relatively small amount of skin surface for heat to escape from its bulky body. And the larger the penguin, the stronger this heat-conserving effect.

So it's probably no coincidence that the largest species of penguin live in the coldest environments. In fact, we see this effect of body size in other cold-adapted animals. species living in frigid environments tend to have larger body masses and relatively stubby appendages like ears and noses. This decreases the surface area to volume ratio, helping the animal conserve heat. This phenomenon has a name, Alan's Rule. There are examples of Allen's rule among bears, foxes, rabbits, and so on. So what is the largest penguin species? That would be the emperor penguin.

Aptenidites Forsteri. It could also be pronounced aptanodotis. These birds stand up to four feet tall, which is about 1.2 meters. They weigh between 70 and 100 pounds,

or 32 to 45 kilograms. The smallest penguin is the little penguin, eudiptala minor, also known as the fairy penguin or little blue penguin. These cute little nugget are only about 18 inches long, or 45 centimeters.

So, about the size of a crow. Remember that we always use the crow as our standard unit of size comparison. Little penguins are indeed a bluish gray color, which is a lot different from the typical plumage of penguins. Continuing on with the body form of penguins, the wings of penguins are rigid, paddle-like structures. We more often call them flippers. They're so rigid that they can't fold up.

up like the wings of more typical birds. Penguins haven't been able to fly through the air for millions of years. Their flippers, however, act like powerful wings underwater. Penguins flap their flippers to propel themselves, sort of like flying through the water as they chase fish or other prey. Bill's shape among penguins is mostly thick and strong, cone-shaped or flattened from side to side, or in other words, laterally compressed.

Bill lengths vary. Some are long, pointy and elegant like those of king and emperor penguins. Others are more stubby like those of rockhopper penguins. Plumage in penguins is, as we all know, mostly some combination of black and white. But some species, like kings and emperors, are a bit more gray or silvery overall. That penguins look sort of like they're wearing little tuxedos or business suits is one of the things we find charming about them. If we can trust what the internet tells us, it seems that, apparently, the Chinese word for penguin translates as business goose. Perhaps when Chinese scholars first encountered penguins, they said, now there's a goose who's dressed for success. It clearly

thinks outside the box. It burns the candle at both ends to push the envelope. That bird is a team player and a real go-getter. We shall call it a business goose. Now, it might shock you to hear that I don't speak Chinese, but I did a little research about this whole business goose thing, and it seems there are other interpretations that aren't quite as funny. The Chinese word for penguin may actually translate as standing goose or tiptoeing goose. Ah, oh well. The actual function of a penguin's two-tone plumage pattern has to do with camouflage, camouflage for a penguin to hide from its predators, and camouflage for sneaking up on its prey. The pattern of being dark on top and lighter underneath shows up again

and again in the animal world. It's called countershading. Imagine a penguin zipping around underwater. If you're a hungry predator at the surface, looking down on the penguin, the bird will be a dark object against a dark background. Bam! Camouflage! Similarly, if you're a sneaky predator lurking below the penguin, looking up, the pale belly of the bird will blend in with the light background. Bam! Camouflage! We find countershating like this in killer whales, sharks, fish, and many other creatures. The plumages of some penguin species also have splashes of bright orange or yellow color. For example, penguins in the genus Eudiptees sport long, colorful plumes on their heads. These birds look like they have oversized yellow or orange eyebrows. Penguin plumage has some other

interesting features. First off, feathers on a penguin are far more uniform in size and shape than on a typical flying bird. From a distance, the contour feathers of penguins look almost like the scales of fish, or they can look sort of like fur. Feathers grow pretty much everywhere on the penguin's skin. In most other birds, there are some significant patches of bear skin on the body called apteria. We may not see these bear patches because they're often hidden by the surrounding feathers. But penguins don't have apteria, except for some species that have a little bear skin on their faces. You'll often hear that emperor penguins have the densest plumbus. of any bird, the highest number of contour feathers per square inch. This would make sense,

since having overlapping feathers packed tightly would help to keep a penguin dry and warm. But although penguins do have well-packed feathers, there's another type of bird that wins the blue ribbon for having the densest plumage. These are the dippers. The five dipper species are songbirds that swim around in icy streams and rivers. The white-throated dipper actually has six times as many contour feathers per square inch compared to an emperor penguin. Biologists estimate that an emperor penguin has something between 24 and 34,000 contour feathers. These provide waterproofing and protection from wind and abrasive ice. But to keep warm, a penguin needs insulation.

For this, the bird depends mostly on its down feathers, or plumeules. For every one contour feather on an emperor penguin, there are several insulating plumeules. And penguins even have some other types of insulating feathers beyond plume mules, but we'll just leave it at that for now. It's critical for a penguin to take good care of its contour feathers, so penguins spend a lot of time preening. They use oil from their euripigial gland to condition their feathers, to maintain their waterproofing. Most penguins shed their entire coat of feathers once a year. This process, known as molting, is common throughout the avian world. Feathers don't last forever, and they need to be replaced regularly.

Unlike other birds, however, penguins lose all their feathers at once. Over a few weeks, a penguin goes through a catastrophic molt. That's really the technical name for it, catastrophic molt. While the penguin waits for its new coat of feathers to replace the old, it can't go swimming without the risk of freezing to death. No swimming means no eating. So penguins typically have to fast while molting. They fatten up before molting and then just hang around,

looking disheveled and awkward until their new plumage is complete. Moving on to what penguins sound like. We all remember what penguins sound like from those old sea and say toys. right? The toy shaped like a circle with the pull string and the plastic arrow that spins around in the middle. You pull the string, the arrow spins, then stops

on maybe a sheep, for example. The sheep says... Remember that? And when it landed on the penguin, you heard... The penguin says. If you don't remember there being a

penguin on that toy, you're not alone because it never happened. But that braying sound was from a real penguin. It was a Magellanic penguin, Sphiniscus Magellanicus. That species breeds on the coasts of Southern Chile and Argentina. Here again is the Magellanic penguin. Penguins in general make similarly strident, somewhat unmusical, sounds. Here's the king penguin, Aptenidites Patagonicus, calling in Tierra del Fuego at the tip of South America. And how about the little penguin? Here's one in New Zealand.

Penguin breeding colonies can get pretty raucous with the calls of hundreds or thousands of adults and their chicks. Here is a penguin colony on the Falkland Islands in the South Atlantic. These are Gen 2 penguins. Listen for the high-pitched peeps of chicks behind the cacophony of the adults. And lastly, here's another breed. colony. This time we're hearing

Emperor penguins and their chicks. Let's take a look now at how penguins get around, both in the water and on land. The penguin family is one of only five bird families in which every species is flightless. Other examples are the Kiwi family and the ostrich family. Over the long course of their evolution, penguins traded in their ability to fly through the air to become skillful, efficient swimmers. Taken as a group, they swim faster, farther, and deeper than any other aquatic birds. A penguin propels itself through the water by flapping its rigid

flippers. These work like wings rather than paddles. They provide lift through the medium of water, just as wings provide lift through the air. Penguins have close to neutral buoyancy in the water, so they don't have to fight gravity the way a flying bird does. This makes swimming relatively efficient, since most of the energy used for flapping gets translated into forward movement. Powerful pectoral muscles in the bird's breast drive the flapping motion. And the penguin's pecks are enormous. They account for over 75% of the bird's body mass. So what might look to us like a rotund, squishy belly is really more like the rock-hard chest of a bodybuilder. The basic cruising speed for most penguins is around 4.5 miles per hour, or 7.24 kilometers per hour.

When they chase fish or other prey, penguins can swim much faster. The fastest swimmers of all are the GENTU penguins. Those dudes can hit speeds of 22 miles or 36 kilometers per hour. When penguins really need to get ripping like that, they do what we call porpoising. They swim like porpoises or dolphins by alternately leaping out of the water and plunging back in. You've maybe seen some of those awesome slow-motion shots of penguins doing this. Penguins and marine mammals porpoise because they have to breathe air. They need lots of oxygen when swimming at top speed.

So they're forced to stay close to the surface. But the path of least resistance is actually to jump into the air when taking a breath, rather than plow along at the water's surface, because, you know, physics and stuff. Some penguin species are content to swim around in relatively shallow, near-shore waters, down to maybe 120 feet or 35 meters. But other species specialize in making deep dives to find food. Dive depths and durations vary across species, but all penguins are superbly adapted for diving.

For example, penguins have solid bones. Most other birds have quote-unquote hollow bones, which come in handy for flying efficiently. Solid bones, on the other hand, are more ideal for diving birds because they reduce buoyancy. Another set of diving adaptations in penguins is related to the use and conservation of oxygen during a dive. A penguin can take only a single deep breath before torpedoing into the same. the briny deep. Oxygen is stored not only in the lungs, but also the blood and in those massive muscles. Most of what we know about diving physiology in penguins comes from research on emperor penguins. And not coincidentally, this species is the most amazing diving bird in the

world. A diving emperor can stay down for over 20 minutes at a time. The current record is a wee bit over 32 minutes. Imagine holding your breath for 32 minutes. But if you were like a penguin, you wouldn't be just sitting there. You'd be holding your breath while running around at full speed, chasing your favorite food, like hot dogs or something. In my case, I'd be chasing burritos. Meanwhile, the pressure around you would be unbearably crushing at up to 40 times higher than normal. Oh, and you're in ice cold water the whole time. Doesn't sound like fun, does it? But all of that is fairly routine business for a business goose. To slow the rate of oxygen consumption, a penguin's heartbeat slows down.

It might beat only 15 to 20 times per minute, or even slower. Even with this adaptation, an emperor penguin burns through its supply of oxygen in about five minutes. Then it has to switch to anaerobic metabolism for the rest of the dive. Scientists don't have a ton of data on average dive. depths and durations for all penguin species. Again, it's the emperor that we know the most about. This species usually dives no more than about 160 feet or 50 meters. But the dive depth record for an emperor penguin is over 1,800 feet, which is 564 meters. Isn't that just incredible? So that's swimming and diving. We all know that penguins are a little less graceful

when it comes to moving around on land. The ways they waddle and hop around are actually part of their charm. Besides waddling and hopping, a few species, like the little penguin, can sort of run, just not very fast. Species that live in the polar region have another more efficient mode of locomotion

for traveling across snow, tobogganing. Here, the penguin falls forward on its bulging belly and scoots forward by pushing with its feet. By tobogging, a penguin can get from point A to B faster and with less energy than walking. A penguin might move as fast as a person jogging when tobogging at top speed. At least in Antarctica, adult penguins don't have any land-based predators to worry about. Toothy, bloodthirsty beasts lurk in the water, most definitely, but up on the ice, it's relatively safe. This may be why penguins seem so ungainly on land.

natural selection hasn't put much pressure on them to be any better at walking or running. Waddling and tobogganing around at relatively slow speeds works just fine when there aren't any predators on your tail. But make no mistake, penguins can really get around when they need to. Some emperor penguins walk up to 70 miles to get from the ocean to their breeding colony. It just takes a while. And penguins in general, especially the smaller species, are more. more agile than you'd think, just by looking at them. Most species are astonishingly skillful climbers, whether scrambling up the side of an iceberg or hopping up a rocky cliff. They use their

strong claws and bills to get traction. We'll shift gears now to look at the diversity of penguins, as well as their global distribution and habitats. Sphanicity is the technical name for the penguin family. It sounds like the first letters there are S-F, but they're actually S-P-H. The root comes from the Latin word for a wedge, sphiniscus. Apparently, a biologist way back in the 1700s thought penguins looked wedge-shaped. But I don't know, that's a stretch, don't you think? I'd go with spindle or football-shaped.

Maybe that biologist was referring to the penguin's bill. The bill seems more wedge-shaped to me. Anyhow, the family sphenicity contains 18 penguin species. Not surprisingly, there's still some debate among ornithologists about the exact number of species. There might be as many as 21 species. But as usual, I'll stick with the current taxonomy used by eBird, which is clenophobic. checklist. These 18 penguin species are divided into seven genera. The most diverse genus is Eudiptees, which has seven species. Naturally, we don't have time here to go into detail about

each of the 18 penguin species. But I just want to take a moment to mention the macaroni penguin, Eudiptees Chrysolophus. This is a medium-sized penguin. At a little over two feet tall, it's halfway between the size of an emperor and a little penguin. The macaroni penguin has a heavy orange or reddish bill, red eyes, and long yellow plume feathers that sweep back from its forehead and over its eyes. This is more or less what the other six species in the genus Eudiptees look like. We call this group the Crested Penguins. Well, Benedict Cumberbatch calls them Crested Penguins.

But don't listen to him. There are more macaroni penguins in the world than any other sphenicid. It's the most abundant penguin species. Macaronies come to land only when breeding. Otherwise, they spend their lives out at sea, swimming around in pursuit of prey like krill and lanternfish. It's my opinion that every kid needs to know about the macaroni penguin. I mean, kids love penguins and kids love macaroni, right?

It's perfect. And perhaps you've been wondering this whole time where this bird got its funny name. Maybe some Italian sailors a few hundred years ago were exploring a sub-Antarctic island when they came across one of these little penguins. The explorers were like, Hey Giuseppe, come over here and look at this goose. He has a yellow and he's headed like somebody spill a bowl of pasta. Let's call him a macaroni.

It's a funny name, Macaron. That's not actually what happened. The name macaroni in this case was a sort of pejorative used in 18th century England to describe a man who is overly concerned with his clothes and fashion. A dandy, a fop, an early version of a hipster, you might say. English explorers who saw macaroni penguins for the first time thought it was a fitting name for these sharp-dressed little birds. All right, refocusing our discussion of the

the family Svenicity. Just looking at the general appearance of penguins, you might guess that their closest relatives are birds like puffins, meurs, and gillimots. But you know better than to be fooled by superficial appearances, you can't always judge a bird by its cover. Thankfully, ornithologists have worked out most of the real evolutionary relationships among the world's bird families using anatomical and genetic data. The closest relatives of penguins are actually the shear waters and petrels of the family procellariadi and the albatrosses of the family diomedeidae. These birds look almost nothing like penguins, do they? So what about those puffins and meurs? I'll come back to them in a few minutes when we talk about evolution. If we look at a

globe to see where penguins are found across the planet, we see a couple things. First, penguins live almost exclusively in the southern hemisphere. The Galapagos penguin, Sphiniscus, mendiculus, is the only exception. It can be found just barely north of the equator, but that's it. Another species that approaches the equator from the south is the Humboldt penguin, Svaniscus Humboldt-Eye. It gets up into the coastal area of northern Peru. Members of the penguin family live on every continent in the southern hemisphere,

including Africa and Australia. Now, it's my civic duty at this juncture to point out that there are no penguins in the far north, in the Arctic. I've said it before. Contrary to what we learned on TV, no wild penguin has ever run afoul of a polar bear or Santa Claus. Forget about chili-willy and those Coca-Cola commercials. Those were all lies. The second major pattern we see in the distribution of penguins is that most of them breed on islands. If we can point to a hot spot of penguin diversity, it would be a widespread collection of islands and coastlines

in the sub-Antarctic latitudes, from the southern tip of South America all the way around to New Zealand. Ten species live across this area. The hottest penguin hotspot would be the region including New Zealand, Tasmania, and the many smaller islands south

of them. This is the stronghold of those crested penguins in the genus Eudiptees, including our buddy, the macaroni penguin. But what about Antarctica, you ask? Yes, what about it? The running gag here on the science of birds is that I kind of make fun of Antarctica. Many of the bird families we've talked about so far have been cosmopolitan, meaning that they're found all over the world. But until today, there's always been an asterisk attached to the word world. All across the world, asterisk, except for

Antarctica. Well, Antarctica, here's your moment to shine, your 15 minutes of fame. I begrudgingly admit that, yes, you do have some birds. Luckily, they are spectacular birds, so good for you, Antarctica. Seven penguin species can be found on this continent. Two of them breed pretty much only in Antarctica, the emperor penguin and the Adelie penguin, Pygoscelis Adelii. In terms of habitat, penguins depend on cold oceanic waters. These environments are highly productive, meaning they're rich with fish and other critters that penguins prey on. The southern ocean that forms an enormous ring around Antarctica offers expansive habitat for penguins. Those more northerly species like the Galapagos penguin still depend on cold water habitats. Ocean

currents around the Galapagos Islands cause upwelling. This is where cold, nutrient-rich water moves from the depths to the surface. Warmer tropical waters don't have enough nutrients to produce the same biomass of fish. So there just isn't enough food for penguins in most of the tropics. Penguins need habitats on land to lay their eggs and raise their families. We tend to picture penguins breeding on ice and snow, but that's true for only a few species. Most of them lay their eggs on sandy beaches or rocky coastlines.

And the Fjordland penguin, Eudiptese Pachyrinkus, that species actually breeds in the coastal rainforests of New Zealand. Almost all penguin species migrate. They travel sometimes long distances from the habitats where they breed to where they molt and then on to where they forage in the non-breeding season. They sometimes travel thousands of miles on these annual movements. I talked a little about the evolution of penguins in the intro. I want to return to this topic briefly. By studying penguin fossils, avian paleontologists, also known as paleonathologists,

have worked out roughly where on earth it was that penguins first evolved. These birds first appeared on the continent of Zeelandia. Never heard of it? Well, I didn't make it up. It's real, I tell you. Zelandia is sometimes referred to as the eighth continent, and it's still around. It's just that these days most of the continent is sunken beneath the waves. The largest chunks of Zeelandia that rise above the ocean today are the islands of New Zealand and New Caledonia. Data from fossils and the genomes of penguins suggest that this group of birds first became distinct around the time of the mass extinction event that killed most of the dinosaurs. That was 66 million years ago. It's still uncertain whether penguins first evolved before the big extinction or a few million years later. Either way, the penguin lineage has been around a heck of a long time. And I think it's interesting that, all of these millions of years later, a lot of penguin diversity

is still concentrated around New Zealand. The genus Aptenidites, which includes the king and emperor penguins, is the most ancient of the living branches within the family, Svenicity. These guys seem to have branched off on their own sometime between 10 and 40 million years ago. They're the largest of the modern penguins. But once upon a time, there were some monster penguins that would have dwarfed any that we see today. About 30 to 40 million years ago, the southern seas around New Zealand, New Zealand and beyond were home to beasts like Anthropornus.

Anthropornus was a giant penguin that stood six feet or nearly two meters tall, and it weighed about 200 pounds. That is one serious business goose. And if you look at the genus name for this bird, Anthropornis, you can probably figure out that it translates to man bird. Anthropornis was indeed a man-sized bird that stood upright like a human. Pretty wild, and maybe even a little terrifying. This also makes me imagine how, if evolution had played out a little differently,

penguins could have kept growing larger and larger. Something like the vortex from Afterman could have come to exist in reality. But, alas, scientists think that Anthropornis and other giant penguins went extinct about 20 million years ago because they couldn't compete with the early ancestors of whales and dolphins. Earlier I said I'd return to the connection between puffins and penguins, and that's where we've arrived. Puffins, meurs, ocklets, and all those adorable little buggers belong to the family Al-Sidae. Collectively, they're known as Ocks, A-U-K-S. Despite some resemblance between ox and penguins, they are only very distantly related.

The two groups of birds look similar because natural selection. has honed them similarly, but independently, to occupy a similar niche. Ocks and penguins are diving birds that pursue fish and other prey in cold oceanic waters. They both propel themselves with their wings underwater, and they breed in colonies along the coast. It turns out that certain adaptations, like having plumage with strong counter-shading, are really beneficial for this lifestyle. So at least some of the resemblance between birds in these two families is because of the fascinating phenomenon of convergent evolution. Turning our attention now to conservation.

Everyone loves penguins, right? So I'm sure we humans have done everything in our power to protect these birds and their habitats. Well, yes, and no. No doubt thousands of people are working to understand the needs of penguins. and working to conserve their populations. It's just that, on average, the human species has made life a lot harder for these birds. While a few penguin species seem to be doing okay, the trend for most of them is that they are in decline.

Twelve of the eighteen species are categorized in some level of risk on the IUCN's red list, including five that are considered endangered. For example, both the Galapagos penguin and the African animals, penguin are endangered. As I mentioned, most penguin species tend to breed on islands. You've heard me talk again and again about the vulnerabilities and conservation challenges faced by island-dwelling birds. Penguins on some islands have been hit hard by non-native predators like rats and stoats. Other threats faced by at least some penguin species include oil spills, pollution of the ocean in general, entanglement in fishing nets, and competition

with commercial fisheries. Penguins everywhere depend on cold water, and cold oceanic water is becoming increasingly rare as the planet warms up. Climate change is a big part of the equation in penguin conservation. You knew we couldn't get through this without climate change rearing its ugly head.

Water temperature has an enormous influence on what fish species can live where. The cold dependent fish and krill species eaten by penguins are declining, in many places where temperatures are rising. Rising ocean temperatures may have other negative effects on penguins, like the decrease of sea ice and an increase in violent storms that hammer breeding colonies. Faced with these and other threats, some species are predicted to decline by 60% or more by the end of the century. But it's difficult for scientists to

accurately predict the outcome of climate change for each penguin species or each population. A major challenge is that there are complex interactions and feedback loops between many of the variables, ocean temperature, sea ice extent, fish and krill abundance, and so on. But no matter how you look at it, it seems like the penguin family overall won't be doing so well in the coming decades. Not unless we can stall or at least dramatically slow the rate of global warming, especially since parts of Antarctica are heating up faster than just about anywhere else on the planet. We've been touching on the subject of what and how penguins eat all along the way today. But there's a couple more points to make about their diet and foraging.

Depending on the species, penguins specialize in features. on small fish or free-swimming crustaceans like krill. Squid is another favorite food, especially for the larger penguin species that can dive deep to hunt for these cephalopods. Fish and squid are slippery, wiggly critters. Penguins don't have teeth to hook into these prey, the way a shark or a dolphin does. So what do penguins have instead of teeth? Well, if you've ever seen the inside of a penguin's mouth, I'm sorry. I'm sorry. You might still be suffering from PTSD. It's a mess in there. It looks like the

Sarlac pit from Return of the Jedi, or a sandworm from dune. Rows and rows of flesh-colored spines line the bird's mouth cavity. These structures are made of keratin, and they curve backward toward the gullet. Once a fish gets nabbed, there's only one direction it's going, down the hatch. Even the penguin's tongue is bristling with rows of wicked spikes. So you might want to think twice before French kissing a penguin. Also, penguins don't have lips, so maybe just lay off this whole kissing thing, okay? Getting back to the subject, penguins swallow their prey whole. Or if a fish is too big, it might be torn into a few pieces first. Unlike many other types of birds, penguins don't have a crop. Recall that a crop is an

enlarged part of the esophagus used to store food, like a satchel. What penguins have instead is a special chamber of the stomach called the proventriculus. The proventriculus is where adult penguins store and sort of predigest food for their chicks while out on long foraging journeys. Some penguin species forage far out at sea, others hang close to shore, some dive deep, some stay closer to the surface. Because of these different foraging strategies, multiple penguin species can sometimes coexist in the same breeding and feeding areas without too much competition for food. With their mouths full of nightmarish spines, penguins are a terror to small fish and krill. But penguins themselves are hunted by an assortment of predatory sea monsters. Penguins get eaten by

killer whales, sea lions and seals and sharks. Little penguins, that's little penguins with a capital L and capital P, that species is small enough that those guys sometimes get snatched and carried off into the sky by white-bellied sea eagles. In the waters of Antarctica, the massive leopard seal is a continuous prowling threat. Leopard seals ambush penguins at the water's edge, as the birds are diving off the ice or when they're returning from foraging. Leopard seals are scary. Can you imagine living like that? What if every time you made a trip to your kitchen to pull some lunch out of the fridge, you knew there was a non-zero chance, maybe even a good chance, that a huge tiger was going to burst out of nowhere, coming at you full speed with its claws and teeth?

Would you want to go into your kitchen? probably not, but you got to eat, right? So do penguins. They have no choice but to face the terrors of the deep. Our last topic is how penguins reproduce. There are loads of fascinating jaw-dropping and heartwarming facts about this part of the penguin life cycle. So many facts that I could probably fill an entire episode or two or three just talking about the breeding behaviors of penguins. We'll just be scratching the surface here today. Penguins are monogamous.

They generally stick with the same partner throughout a single breeding season. Some species tend to find a new mate for each year that they breed. For example, only 15% of emperor penguins keep the same mate from one year to the next. Other species, such as the little penguin, form long-term bonds and pair up more faithfully with the same mate year after year. Most species breed in colonies. A penguin colony might have a couple hundred birds or it might have hundreds of thousands.

You've probably seen some documentary footage of these immense penguin colonies. They are truly one of the grand spectacles of nature. The sound of hundreds of thousands of penguins honking, braying, barking and whistling is the definition of, a cacophony. This Spanisid symphony

isn't something I've experienced personally. Not yet. Visiting a penguin colony is definitely on my bucket list. I've seen Galapagos penguins and Little Blue Penguins in the wild. One or two individuals here and there. But I'd love to see a big colony up close and hear all that racket with my own ears. But I'll also need to be ready to smell all those penguins with my own nose.

The aroma of guano from a hundred thousand penguins is, I'm told, less than pleasant. Having been to the penguin exhibit at the zoo, I've had a whiff or two myself. But I imagine having to smell penguin poop is a small price to pay for getting to experience a colony in the wild. Now, you'd think that scientists would already know where every penguin colony on the planet is located. I mean, it can't be that easy for a massive cluster of no. noisy, stinky penguins to go unnoticed, can it? Well, the world is a big place, and even today it's challenging for researchers

to explore the extreme southern latitudes, especially Antarctica. So, it seems, scientists have yet to map out every last penguin colony. In the last 10 years or so, scientists have made some exciting discoveries in this regard. Satellite images have revealed the locations of previously unknown emperor

and Adeli penguin colonies. But the birds themselves are too small to see with satellites. So how does one detect a penguin colony from space? Look for the poop, of course. A penguin colony is plastered with heaps of guano. It makes a giant recognizable stain that satellites can actually detect. As an example, it was only a few years ago that researchers examining satellite photos

found what looked like a large adelee penguin colony on the Danger Islands. These islands are at the far northern tip of the Antarctic Peninsula. A year later, the researchers made an expedition to ground truth what they saw in the photos. Lo and behold, it turned out that there are about 1.5 million Adeli penguins breeding on the danger islands. This is one of the largest concentrations of Adelis anywhere. and these are some of the largest bird colonies on the planet, period. And yet, until just a few years ago, we didn't know they were there. Pretty cool, huh?

Okay, let me get back on track here. Penguins have courtship behaviors involving some combination of calls, ritualized displays, nest building, and gift giving. Males usually arrive first at the breeding colony each year. When the females arrive, they pair up with either their mate from previous years or a new mate. Again, that depends on the species. The traits penguins use to assess their potential mates vary. For some species, it's mostly about the song or the physical condition.

For others, it's the quality of the nest. Remember that animated kids movie that came out in 1995, The Pebble and the Penguin? No one else does either. It was a box office bomb. Well, actually, there's one person who watched The Pebble and the Penguin, and that person is my wife. In fact, she knows the title song by heart, and will belt it out at random. Or she'll cue it up on her iPhone and play it when we're on a road trip. I just have to grit my teeth and suffer through it. I've heard that song so many times I can hear it playing in my head right now.

Oh, the Things We Endure for Love. The Pebble and the Penguin movie was based loosely on the real lives of Adeli penguins. Adelis use pebbles to build their nests. A nest might be constructed using well over a thousand small rocks. This geological resource is in short supply in most Adeli colonies. Each rock, each pebble is highly valuable. So the birds are crazy about rocks. One behavior in Adeli penguin courtship is where a male

brings a rock to the female and gives it to her as a gift. It's pretty cute. But the idea that this is the penguin equivalent of a marriage proposal, with the rock acting like an engagement ring, is not really accurate. It's a partial myth, perpetuated by the pebble and the penguin, and still circulating the internet. The myth is that a male searches for, quote-unquote, one perfect pebble to win the heart of his love interest. In reality, just about any rock of the right size will do. And by the time a male Adeli penguin is giving pebbles as gifts to his lady, the two have already committed to each other.

At least that's my understanding. If we just have to find a parallel in human romance, a rock is more like a flower bouquet to Adelis or a box of chocolates. The rock just strengthens the existing bond between the two birds. Adelie penguins are so crazy for rocks that they still. steal them from each other's nests and fight over them. And a female will sometimes sneak away from her mate to go find a bachelor male. She'll offer to mate with the bachelor, if he gives her a pebble.

Then she carries the pebble back to her nest and her unsuspecting mate. Maybe there's a deleted scene in the Pebble and the Penguin movie that shows this scandalous behavior, you know, in the director's cut or extended version? Maybe not. I'll have to ask my wife. Anyway, as penguins of all species find mates each year, there are courtship rituals, and there's likely to be some squabbling and fighting, too. The birds compete with each other for the best mates, sometimes resorting to violence. Once they've gotten through all that and they're paired up and mated,

the penguins get on with the care of their eggs and chicks. Most species make some kind of nest, except for kings and emperors. The nest might be a simple depression on the ground, a burrow, or a pile of rocks. Besides Adelis, Gentoo and Chinstrap penguins also build a nest from piles of pebbles. These little rock piles elevate the eggs so that if it rains or there's a lot of snow melt, the eggs don't get swamped with water. Two eggs per brood is typical, again with the exception of the king and emperor penguins, which each have one egg.

Interestingly, penguin eggs are the smallest of any bird, not in the absolute sense, of course, but relative to the size of the adult. Both parents share in the work of raising their young, from incubating the eggs to feeding and protecting the chicks. And the chicks do need protecting. Eggs and chicks are far more vulnerable than adults to land or air-based predators. Avian predators like giant petrels, scuas, gulls, and caracobas, will snatch eggs and kill chicks.

Penguin parents have to be vigilant against these threats. Penguin chicks are, as you know, absurdly cute. They're covered in hair-like down feathers that keep them warm. They completely depend on their parents for food and protection. The parents take turns making foraging trips out to sea to get food for the chicks. Some of these journeys last for months and cover thousands of miles. When it's feeding time, a parent regurgitates a slurry of partially digested fish bits and whatnot into the mouth of its hungry chick. It's like if they served smoothies at Long John

Silvers, that sketchy fast food seafood restaurant. Mmm, this smoothie tastes like rancid shrimp and fish guts and stomach acid. Thanks, Mom! Once penguin chicks are mature enough, they're able to wander around the colony to explore on their own a bit. Their parents can leave them unattended while they swim off to find food. The youngsters of some species will gather together into a creche. That's spelled C-R-E-C-H-E. You'd be hard-pressed to find any group of animals filled with as much cuteness as a penguin crush. A creche with dozens of chicks can be looked after by just a few adults.

When a parent returns and needs to find its chick or its mate, it makes a distinct contact call. Amazingly, these individual birds can find each other among the throngs, in colonies that might number in the hundreds of thousands. The time from hatching to fledging varies a lot. In some of the smaller species, like the Galapagos, little, and chinstrap penguins, young birds can fledge by about two months old. At the other extreme is the king penguin. It takes 10 to 14 months before chicks in this species fledge and become independent. King penguin chicks actually have to survive on their own for their first winter, while still covered in fluffy down. They can't swim and therefore can't feed themselves. So they fast,

living off their thick fat reserves while they wait patiently for their parents to return in spring. After fledging young penguins of all species wear their new layers of waterproof and insulating feathers. They're ready to take their first plunge into the cold, dark water, of the ocean. They disperse from their natal colonies en masse. If they can avoid orcas, leopard seals, sharks, and oil spills, they might live long enough to reach sexual maturity. They'll return to their colony to breed for the first time. For little penguins, it takes about two years to mature. But this process takes longer for most other species, maybe five years in king penguins, and up to eight ears for Adelis.

Most penguins can live 20 years or more in the wild. Some individuals in captivity have lived for over 40 years. When we think about the biology of penguins, it's helpful to look past all the Hollywood imagery and the cartoons. Yes, penguins are some of the most charming and adorable animals in the world. I'm a sucker for all that, too. me. But I have to remind myself that these birds are way more hardcore than their smile-inducing appearances suggest. Penguins are tough and resilient. They live in some of the most severe

conditions on earth. They have to deal with terrifying predators on an almost daily basis. And penguins have to deal with each other. They fight over mates and resources, biting with strong beaks and slapping each other with their flippers. These amazing birds live a difficult life. They deserve our respect for their ability to survive, even from just one day to the next. This was a big episode, and I appreciate that you took some of your valuable time

to explore the world of penguins with me. Thank you. A special thank you to my supporters on Patreon, who helped me produce this show. Their monthly contributions offset the costs of running the podcast and generally make this whole thing possible. And here's a shout out to my newest patrons, Tim and James. Thanks so much for your generous help, my friends. If you are interested in supporting this podcast as a patron, you can check out my Patreon page at patreon.com forward slash science of birds. I also want to thank my good

friend David Jaffe for sharing his insights into penguin behavior. David has visited Antarctica and other penguin-rich areas many times as a professional naturalist and photographer. You can see some of his amazing penguin photos in the show notes for this episode on the Science of Birds website, scienceofbirds.com. If you have something you'd like to share with me, maybe about the podcast, or about that one time when you French kissed a macaroni penguin, go ahead and shoot me an email the address is ivan at scienceofbirds.com this is ivan phillipson

and i look forward to the next time we dive into the wonderful world of birds together cheers