The Science of Birds - Seabirds

Episode Date: June 9, 2023

This is Episode 77. It's an overview of seabirds. Some might call them Oceanic birds or Marine Birds.How do we define what is or isn’t a sea bird?Well, it depends on who you ask. There’s no one definition, since “seabird” is an informal term, rather than a scientific one. It doesn’t correspond to a single taxonomic category, or to a single evolutionary lineage.Here’s what the authors of the book Oceanic Birds of the World have to say about it:“To our mind, true seabirds are birds of the ocean, birds you generally go on a boat to see. Yes, some of these species can be seen from shore (and almost all come  ashore somewhere to breed), but the birds we include here are species that make  their living from the ocean for all or most of the year, and often not from coastal waters.”Oceanic Birds of the World is a field guide, and it includes about 270 species. Other authorities might say there are between 300 and 350 seabird species. In this episode, we'll talk about the various types of seabirds and what taxonomic groups they belong to. We'll look at how seabirds face the challenges of live on the ocean, how and where they breed, and how they find food.Links of InterestBass Rock - the tiny island that gannets love [video]Far From Land: The Mysterious Lives of Seabirds [book]  ~~ Leave me a review using Podchaser ~~Link to this episode on the Science of Birds website Support the show

From the heaving, rolling deck of a fishing boat, I looked out at dark cyan waves and thick rain clouds. Surrounding the vessel in all directions were flapping streaks of black, white, and gray. These were birds, of course, of various sizes. Some pigeon-sized, others with wingspans wider than any eagle. This was in the chilly waters off New Zealand's east coast. I was on my first pelagic birding trip, and I was in heaven. Thank you, anti-motion sickness medication. Without that, I would have been in hell instead,

curled up in the fetal position on the deck, begging for someone to please kill me and toss me overboard to feed all those hungry birds. The bird species swooping and swimming hungrily around the boat, Huttons and short-tailed shearwaters, Cape Petrels, Westland Petrels, Northern Giant Petrels, Fairy Prions, and three species of Albatross, including the Wandering Albatross. For decades, I had wanted to see a wandering albatross. At up to 11 feet or 3.35 meters from wingtip to wingtip, no other bird has such a large wingspan.

And there it was. a wandering albatross right in front of me. Birds like these are perfectly at home in the open ocean. There's is a world that, for landlubbers like most of us humans, can seem at once, beautiful, mysterious, desolate, even alien. But we live on a planet that's mostly ocean, right? Over 70% of the Earth's surface is covered by marine habitats. So I guess it's not surprising that birds Birds, resourceful, adaptable little buggers that they are, have taken advantage of the opportunities offered by the sea. Every day of every year, the world's oceans are criss-crossed by millions of birds as they

fly or swim around, in search of food, safe places to rest, and places to raise their chicks. We can't personally witness most of that activity, but it's happening. Seabirds, at least in my opinion, and I hope you'll soon agree, are some of the most incredible animals on Earth. Hello and welcome. This is the Science of Birds. I am your host, Ivan Philipson. The Science of Birds podcast is a light of birds. hearted exploration of bird biology for lifelong learners. This episode, which is number 77, is all about seabirds. Some might call them oceanic birds or marine birds.

And I don't think it would be wrong to call them birds of the briny deep. Or maybe even something cool like the feathered minions of Poseidon. But we'll stick with seabirds. This episode is an overview of this group. group. But how do we define what is or isn't a seabird? Well, it depends on who you ask. There's no one definition since seabird is an informal term rather than a scientific one. It doesn't correspond to a single taxonomic category or to a single evolutionary lineage. Here's what the authors of the book Oceanic Birds of the World have to say about it. Quote, to our mind,

true seabirds are birds of the ocean, birds you generally go on a boat to sea. Yes, some of these species can be seen from shore, and almost all come ashore somewhere to breed, but the birds we include here are species that make their living from the ocean for all or most of the year, and often not from coastal waters. End quote. Oceanic birds of the world is a field guide, and it includes about 270 species. Other authorities might say there are between 300 and 350 seabird species. Birds that, quote-unquote, make their living from the ocean for all or most of the year are what we call pelagic birds.

I used that word in the intro, right? Pelagic. It means relating to the open sea. So when you go on a pelagic birding excursion, you get on a boat, the boat motors away from the coast and you end up miles and miles out to sea. The avian cast of characters you find out there can be much different from those you see from shore. Humans have had a long relationship with seabirds. Sometimes we're friends, sometimes we're enemies. Sailors, fishers, and I'm guessing pirates back in the day could get useful information by

watching seabirds. Flocks of birds might, for example, reveal the presence of large schools of fish nearby. But when it comes to catching fish, birds have also been seen as our competitors. They've been persecuted and hunted for millennia. Today, seabirds face many pressures from the human world. They're having a hard time. Until very recently, it's been hard for scientists and conservationists to actually figure out how seabirds are doing. These critters have been very difficult to study. Many of them swoop around at high speed over the featureless ocean for months or years at a time, staying hundreds or thousands of miles away from land. But this is the 21st century, yo! We got all sorts of gadgets and stuff.

advances in technology like the miniatureization, it's a little hard to say, the miniaturization of satellite trackers have made it possible for scientists to discover so much more about the lives of seabirds. Pretty soon, with all this technology, I bet we'll be able to just ask Siri or Google on our phones to give us some hard data on seabirds. Hey Google, exactly how many waved albatrosses are nesting on the island of Española today, right now. Sorry, I don't have any information about that.

Do you want to hear a joke? No, that's okay. I was just... What kind of bird is always out of breath? A puffin. Okay, well, I guess we'll have to wait a few years before our digital assistance can be actually useful for studying birds. But there really has been a revolution in scientific progress

when it comes to sea birds over the last few decades. and yet we still have a lot to learn about them. In any case, let's go ahead now and dive into what we do know about the biology of the feathered minions of Poseidon. The world's coastlines and oceanic waters have been home to birds for a long, long time. We know this because the fossil record for seabirds is pretty good compared to what we have for many other types of birds. Seabirds live and eventually die in an environment where there's deposition. Sediments like sand, silt, and mud are deposited, laid down sequentially on the shore, on continental shelves, and in deep waters. The skeletons of seabirds that come to rest in those sediments can end up being preserved as,

fossils after millions of years. Paleontologists have discovered fossils of what were clearly seabirds from the age of the dinosaurs, the Mesozoic era. The earliest marine birds that we know of were the Hesperornathies. They existed as far back as the early Cretaceous over 100 million years ago. These guys were specialized for diving and chasing fish around underwater. They probably looked sort of like loons or cormoros. ants, but, you know, with teeth, a mouthful of pointy teeth. Interestingly, many

hesperornathies were flightless. They had gone all in on the swimming way of life. But when the Cretaceous period ended with a bang 66 million years ago, the Hesperonathies all went extinct. But there was another critter that lived right around the time of the big extinction event. This was tithostonics, a bird whose fossilized wingbone was found in New Jersey, as in, oh, New Jersey! Unlike those loon-like hesperornathies, it seems tithostonics might have left some descendants behind. It's possible that this was an ancestor of modern albatrosses and petrels. 66 million years later, here in the magnificent present, we have somewhere between 250 and 350 seabird species on the planet. Let's do a quick rundown of the major seabird groups.

I'll stick with the ones described in the book, Oceanic Birds of the World. Taxonomically, in terms of their scientific classification, seabirds represent five avian orders and about 14 avian families. The first and perhaps most obvious group is the penguins. All penguins are flightless, and they are superbly adapted to a life at sea. Penguins are in the family Svanicity, and that is the only family in the order Svenisiformis. Check out episode 36 of this podcast if you want to listen to me yap about penguins for an hour. The next order is proscelariaformis. All the birds in this order are legit seabirds.

We call them tube noses. tube noses. That's because the nostrils of these birds are enclosed in tubular nasal passages, a feature associated with a keen sense of smell. Within the order procelariaformis, there are five families of seabirds. The family procellariadi is the most diverse, with almost 100 species of shear waters and petrels. Also in this family are the Fulmars, the diving petrels, and prions. Like almost all seabirds, shearwaters and petrels are colonial breeders. I mention this now because I want you to listen to the angelic sounds of a wedge-tailed sheer water colony in the Seychelles Islands, in the Indian Ocean.

The birds here are tucked into their nest burrows, or sitting on the ground nearby. I don't know about you, but listening to those ridiculous, adorable calls makes me very, very happy. Okay, so next we have the 15 albatross species. These are the largest flying seabirds, and they belong to the family Diomedeidae. We're still within the order Proseraleiformis. We have two more families in this order, Oceanaitidae and Hydrobatidae. These are the storm petrels, and there are about 30 species. They're tiny swallow-like seabirds.

In fact, a Spanish name people in Chile use for a storm petrel is Golondrina del Mar, literally swallow of the sea. Storm petrels have to flap their little wings when they fly, rather than soar on the wind like petrels or albatrosses. Birds in the family Oceanitidae are called southern storm petrels, because they live mostly in the southern hemisphere. So you can probably guess what we call the birds in the family hydrobatidae. If you guessed water bats, well, good guess, I suppose, because hydrobatidae, and these little guys do flutter around sort of like bats.

Water bats would be a cool name, but no. Species in the family hydrobatidae are called northern storm petrels. This group is distributed mostly in the northern hemisphere. One member of the southern storm petrel family has what might be the saltiest, most sea-farm. scientific name ever. Wilson's Storm Petrel has the scientific name Oceanites Oceanicus. For real, Oceanitis Oceanicus. Have you ever seen a Wilson's Storm Petrel? I haven't, not yet. Which is interesting because our little friend Oceanitis Oceanicus is one of the most abundant birds in the world. These birds flit around above the waves of every ocean on the planet.

By some estimates, there are as many as 30 million Wilson's storm petrels out there. So, if, like me, you have not seen this species, that underscores just how difficult it is for most of us to see seabirds. Anyway, where were we? All right, we just finished up with the families in the order prosolariaformis. There were four, proselyariidae, daimedei, oceanidae, and hyiheids. Our next order is suliformis. I'll speed up a bit here. In this order, we have three seabird families, sullidae, frigatidae, and fallacrochoracidi. The gannets and boobies are in the family

sullidae. Frigot birds belong to the family fragotidae. Falakro coracidi, and that starts with a pH, is the family of the cormorants and shags. Falakrocoracity is a mouthful, isn't it? In fact, it's one of the longest bird family names with 17 letters. Crazy stuff. If you really want to learn these words, try dropping them into everyday conversation

with your family and friends. You know, Sally, I was thinking the other day about the relative charms of birds in the family's diomedeity and falis. I've actually compiled a list here. Sally? Sally, where are you going? I made a list. Sally! Next up, we have the order, fithontiformes. This order has just one family, and that's the tropic bird family, fithontidae. These words again begin with pH. The last of the five orders of seabirds is caradreiformes. Not all species in this group are what we would call

seabirds, only some of them. There are four families of interest here. The first is Alcidi, the family of the ox, as in A-U-K-S, puffins, murs, gillamots, razorbills, those sorts of lovable football-shaped birds. These are all marine species, so they're all seabirds. The next family is that of the Skuas and Yeagers. Their family name is another fun one to pronounce. Sterkerreidi. I seriously love complex words like this. I love the challenge.

Sterkorariadi. Am I alone in this? Am I crazy? Probably. Next we have a family known and loved by all, Laridae. If you listened to episode 47 of the podcast, you hopefully remember that this is the family of gulls and turns. Sandpipers all belong to the family scolopacity. See episode 26. But most of these are shorebirds rather than true seabirds. However, two species in this family, the red fallow rope and red-necked fallow rope, live a mostly oceanic life, at least in the wind.

winter. So some ornithologists consider them seabirds. We could say the same for some ducks, like iders, and there are critters like brown pelicans and all that sort of stuff, but we don't have all day, so let's just call it good where we are. It took long enough just to give you the order and family names of all these seabirds. There's no way I'm going to describe what all of them look like. I mean, I could do that, but you guys would hate me. I think about 97% of my listeners would click the unsubscribe button well before I got finished detailing the subtle plumage and morphological differences between the black capped petrel and the Bermuda Petrel.

You'd probably bounce on me unceremoniously, just like Sally did. Even though many seabird species are only distantly related, they can still look pretty similar to our eyes. They have some common features. For example, most have a streamlined body, which is an adaptation to both flying and diving. Webbed feet, too, are standard issue among seabirds. Plumage colors in these birds are notoriously unexciting. They aren't red or blue or polka-dotted like so many land birds.

Instead, seabirds are black, white, gray, brown, or some combination of these. Males and females generally have very similar or identical plumage. A handful of species, like the puffins and boobies, have colorful bills or feet or a few tufts of feathers. Humans are suckers for color, so we get pretty excited about puffins and blue-footed boobies. But, of course, a bird doesn't need to be all colorful to be beautiful or charming. Seabirds have loads of charm and personality. and in many cases, elegance aplenty.

Some species have shapes and colors that are so similar, telling them apart at a distance can be pretty tough. Just look at a field guide showing a bunch of shear waters side by side. Yikes. Maybe don't start with this group if you're a beginning birder. I don't want you to get overwhelmed and rage quit. A seabird can be especially hard to ID if it's flying fast, probably away from you while you're watching it from a moving platform like the deck of a boat

and or while you're getting slapped in the face by wind and rain. But the challenge is all part of the fun when it comes to seabirding. The sea is a harsh mistress, quick to anger and slow to forget. as the old saying goes. That's true for human sailors, and I guess it's true for seabirds. Yet, despite the many challenges of the marine environment, seabirds are swarming all over it. They've evolved to thrive in the oceans. The adaptations of seabirds help them minimize the energy they burn

while they go about the business of foraging and breeding. Oceans are vast. Other than water, resources in the ocean, like food, can be scattered across hundreds or thousands of miles, often in a semi-random way. One of the most obvious challenges seabirds face is the need to get around. They need to travel great distances over or through open water. Many species have long, narrow wings. These are what we see on albatrosses, Shear waters, petrels, gannets, and gulls. This wing shape maximizes lift, especially in the wind. Birds with wings like this take advantage of wind blowing over the ocean,

or rushing up the faces of sea cliffs, or whipping over the crests of waves. They can soar passively, barely flapping, and therefore barely using much energy for great distances. For example, gray-headed albatrosses can fly. over 500 miles or 900 kilometers per day in the non-breeding season. At that time of year, some of these birds will circumnavigate the entire continent of Antarctica. Sometimes a gray-headed albatross will circle the globe more than once in a single season. One reason albatrosses and many other seabirds fly such ridiculous distances is that they aren't just making a series of B-lines from one place to another. First off, they have to adjust their flight paths to move with

the wind rather than against it. Second, they often fly in zigzag patterns as they look for food. Other seabirds have gone a different route. They are swimmers and divers. Ocks in the family Alcadie are great examples. Instead of having long, narrow wings, they have relatively short stubby wings, wings that seem to be barely functional enough to get the bird into the air. But wings with that shape work really well as a means of propulsion underwater. Ocks and their lookalikes and distant relatives, the diving petrels, have lost the ability to fly long distances, at least not without burning an obscene amount of energy. But what they've lost in aerial efficiency, they've gained in their ability to zip around underwater in their pursuit of fish.

Penguins have taken this evolutionary trend to the next level. They can't fly at all, but they can dive much deeper and for longer periods than other flying seabirds. Another major challenge for birds at sea is navigation and orientation. Ornithologists still haven't completely figured out how seabirds accomplish this. But from studies on a number of species, it's clear these birds have several adaptations for finding their way around the globe. For example, they combine information from the position of the sun and stars and from coastal landmarks. Some researchers have hypothesized that sound may also be used for navigation.

Specifically, infrasound, super low frequency sounds that humans can't hear but are all over the place in the ocean. What about the Earth's magnetic field? You've probably heard that some land birds are known to use magnetic information to navigate. Until recently, there wasn't much evidence that sea birds use this kind of information.

But in 2020, a group of researchers at Oxford University, published a study that showed strong evidence that Manx Sheerwaters, Pafinus Pafinus, do use magnetic information. After leaving their birth colony in the British Isles, their natal colony, young Shearwaters spend about three years in the South Atlantic. They goof around off the east coast of Argentina, getting into all sorts of trouble. But then they fly thousands of miles to return to their natal colony. That's a pretty amazing navigational accomplishment. This behavior of breeding in the same spot where you were born is called natal philipatry.

That's spelled P-H-I-L-O-P-A-T-R-Y. This 2020 study found evidence that baby Manx shearwaters imprint on the magnetic signature of their natal colony. This allows them to sort of remember the colony's geographic position. They use that magnetic signature to find their way home several years later. But it seems the magnetic field only helps to identify the latitude of the natal colony. The young shearwaters still have to use other cues to locate their colony in the dimension of longitude, of east versus west. Lastly, seabirds can use their sense of smell to navigate the high seas. Many species have keen powers of olfaction, and certain places in the world have a distinct odor.

For example, I was recently walking down Hollywood Boulevard in California, the Walk of Fame and all that. I had a great time, but yeah, I don't think a seabird would have any trouble finding that street based on smell alone. Now, don't worry, I'm allowed to throw shade at California because I grew up there. You know I love you, Callie. We'll talk more about olfaction in a few minutes when we get into how seabirds forage. Because a sense of smell is helpful for finding food, and finding food is another major challenge for seabirds. How do you gather enough to eat for yourself and your chicks in the ocean's vastness? Finding water to drink is a little easier. However, all that water is super salty. A human would die

pretty quickly if they drank seawater instead of fresh water. In my last podcast episode, episode 76, I actually went into detail on how some birds can drink salt water. So I won't repeat all that here. But the basic idea is that they have a pair of salt glands over their eyes that remove excess salts from their blood. The salts then get expelled through the nostrils. I also want to point out that some seabirds may not actually guzzle salt water to meet their needs for hydration. Instead, they can get most of the water they need from the fish they eat, because water in the flesh of fish isn't all that salty.

The last major challenge for seabirds I want to talk about is staying warm and dry. So, thermoregulation. Imagine a black-browed albatross, or more, More impressively, a tiny Wilson's storm petrel flying among towering waves in the frigid seas around Antarctica. Those birds must have some serious adaptations to conserve their body heat. The major distinction of seabirds here, compared to typical land birds, is that many of them have especially dense contour feathers and, beneath those, dense down feathers. These provide a protective and usually waterproof outer shell

and a highly efficient layer of insulation beneath. The amazing abilities of seabirds to fly or swim epic distances, to navigate, to find food, and to keep warm, have allowed them to spread to every corner of the world's oceans. And yet, despite all the adaptations of seabirds, they still have a hard time out there. Storms, predators, competition, starvation, disease, any of these can spell doom for a bird at sea. Dead sea birds wash up on the shores of every continent day after day, year after year.

Sometimes dozens or even thousands of them are found exhausted or dead along a stretch of beach. When there's no obvious cause of death, people call these events Rex, W-R-E-C-K-S. The usual culprit of a seabird wreck is a large, violent storm. If you're a bird of the briny deep, there's really only one reason you have to set foot on dry land. To breed. Like whales, seabirds evolved from land-dwelling ancestors. Whales, however, figured out long ago how to make babies entirely in the water. Birds haven't learned that trick yet. But who knows, maybe someday. Stranger things have happened over the long march of evolutionary time. For now, their need to lay eggs on terra firma compels seabirds to gather on the world's beaches,

bluffs, and seaclifts. The life histories of seabirds differ dramatically in several key ways from those of most land birds. The term life history is from the science of ecology. It means the pattern of events that occur in an organism's life, from birth to death. A bird's life history includes things like its age at maturity, how many offspring it has, its lifespan, and how much energy it puts into growth versus reproduction. For example, if I were to tabulate some data for my own life history, I'd say my age at maturity would be about 52.

That's still a few years away, so I'm just guessing that I'll finally grow up by then. How many offspring do I have? That's a big zero, amigo. And my lifespan? Unknown. I'll let you know how long I lived after I die. And lastly, how much energy have I devoted to raising kids? That's another zero on the data sheet.

Anyway, the noteworthy life history features of a typical seabird are a long time before reaching maturity, a long life, small clutch size, and an extended time required to incubate the eggs and raise the chicks. In terms of a long life, dig this. The oldest wild bird in the world that we know of is a female Lyson albatross. Her name is Wisdom. She returns to Midway Atoll in the Hawaiian archipelago to breed.

Midway, you might have heard, is the site of a famous World War II battle between the U.S. and Japan in 1942. Wisdom the Albatross was tagged, in other words band. or ringed by scientists way back in 1956. The best guess at her age is 72. That's right, 72. Wisdom is old enough to be my mom. My real mom is actually about that same age. Even more incredible is the fact that wisdom is still laying eggs and raising chicks.

It's estimated that she's successfully raised about 30 chicks in her long life. How amazing is that? Seabirds like Lyson albatrosses are almost always monogamous. They either stay with a single partner for years and years, or they just pair up with one mate for a season. But it's typical for a pair to stay together for a long time. Unlike most land birds, which mature quickly and can breed when they're about one year old, seabirds have a long adolescence.

They often don't breed for the first time until they're four to six years old. For some albatross species, they might be ten before raising their first chick. And notice I said chick, singular. Seabirds tend to lay only one or two eggs per breeding season. And they don't necessarily breed every year. Rather than pumping out lots of eggs every year, seabirds invest a lot of time and energy into a single chick, or maybe a pair of chicks. All of this breeding activity takes place in a colony.

Over 95% of seabird species are colonial. Some of their breeding colonies are the largest bird colonies on the planet. For example, the island called Bass Rock, off the coast of Scotland, is home to the world's largest colony of northern Gannets, Morris Bassanis. Notice that in the second part of that scientific name, the specific epithet is Bassanus. Some might pronounce it Bassinus.

Either way, the Northern Gannet's scientific name is a reference to Bass Rock in Scotland. There are about 150,000 Gannets clustered together on that relatively tiny island. On the other side of the globe, crested ocklets in the Bering Sea gather in breeding colonies that might be swarming with a million birds. And the chin-strap penguin colony on Zabodoski Island in the southern ocean also has about a million birds.

If you've ever seen a large seabird colony like this, you know how impressive they can be. They're one of the great wildlife spectacles in nature. I have fond memories of being on a small boat off the coast of Iceland, looking up at towering black cliffs that were teeming with thousands and thousands of northern Fulmars, common mers, thick-billed mers, razor bills, and Atlantic puffins. It was a totally awe-inspiring thing to see. Seabird colonies can be an awe-inspiring thing to smell, too, because, let's face it, they stink. Ew! All that guano, piling up over countless years, gives off a powerful and distinct odor, rich with ammonia.

Sure, the smell of guano is kind of gross, but I don't know. I got to admit, I find it strangely charming. The pungent fragrance of a seabird colony, for me, evokes the romance of the oceanic world. which makes me wonder if scientists that study seabirds in the field, at least some of them, grow to actually like the smell of guano, or at least become indifferent to it. Seabirds establish their colonies on islands or rugged cliffs on the mainland coast. These sites are usually inaccessible to predators like land mammals. It might be that the safety of the colony is what allowed seabirds. to evolve their special life histories.

Because if you're a bird and you're not constantly threatened by a bunch of furry salivating predators, it probably makes sense to mature slowly, raise fewer chicks per season, take really good care of the ones you do have over an extended period, and live a long life. This life history strategy, combined with colonial breeding, seems to be what works best for seabirds. We've already heard the sound of a wedged-tailed shearwater colony and of a northern Gannet colony. Now here's the tranquil sound of a bunch of streaked shear waters on an island in Japan. When seabirds are ready to breed, they arrive at a colony and begin. to pair up. They either get reacquainted with their partner from last year, or they find a new one,

sort of like human teenagers returning from their summer break at the start of the school year. And like teenagers, pair bonding in seabirds usually involves elaborate courtship displays. They call to each other, perform ritualized dance moves for each other, clack their bills together, and so on. Such behaviors are seen when two birds get together for the first time. But even pairs that have been together for months or years often reinforce their bond by making such displays. Let's listen to a pair of Lyson albatrosses on Midway Atoll. They're dancing for each other, grunting and whistling and clappering their bills.

Bill clappering is when a bird makes a rapid clicking sound by smacking the tips of its upper and lower mandibles together. Isn't that just a fantastic thing to hear? So a pair of seabirds do their little dances and their other courtship behaviors. If all goes well, they eventually mate. Seabird nests can be on flat ground, on a rocky ledge, or crevice, in a burrow, or, for a minority of species, among the branches of small trees or shrubs. Each species has its own way of doing things. Red-footed boobies and some frigate birds nest in trees or shrubs. Puffins and petrels dig burrows. Gannets and albatrosses

make mounds or scrapes on open ground, and so on. Some types of seabirds, like all those in the order prosolariaformis, leave the colony right after mating, after copulation. They say to their mates, Thank you, that was nice. Really, it was, but I'm like literally starving. I've got to bugger off now and go get some grub. Then they fly off to the horizon.

This phenomenon is called the pre-laying exodus. The birds will spend up to several weeks flying around and foraging on the open ocean, wherever their food is abundant. During this pre-laying exodus, the birds fatten up. The female needs calories to make an egg or two, and both parents build up a reserve of energy for the incubation period that will soon begin. Because incubation in seabirds can be a long haul. maybe only a few weeks for small birds like turns,

but incubation can last up to 10 weeks in birds like albatrosses or large penguins. Sufficiently fattened up after the pre-laying exodus, a bonded pair return to their nest site, and the female lays her single egg, or in some cases a couple of eggs. One of these eggs can be very large relative to the female's body size. For example, a storm petrel egg can be about 25% of the female's mass. If an average-sized human mother gave birth to a baby that was 25% of her mass,

the kid would weigh like 38 pounds, which is 17.3 kilograms. Can you even imagine what a 38-pound baby would look or sound like? Terrifying, I'm sure. Like, you hear a normal baby crying and it sounds like this, right? But a 38-pound baby, it would probably sound more like this. Well, let's try to forget about giant creepy babies. Better to stay focused on seabirds. So now the egg has been laid and incubation begins.

The parents incubate in shifts. The male usually takes the first shift while the feet. female heads out to the ocean. She needs to replenish her body with food after making that ginormous egg. An incubation shift might last five hours or it might last 20 days. It varies, but larger birds tend to take longer shifts. While one parent is out stuffing its gullet with squid or krill or fish, the other parent just sits there stoically on the egg, not eating or doing much of anything. for days or weeks. The parents keep taking shifts like this until junior busts out of its egg, at last.

Then begins the brood guard stage. The parents continue taking shifts to brood the young chick and to feed it. One parent is always there to protect the vulnerable young bird from the elements and avian predators. The other parent out foraging for the chick will sometimes fly amazingly. long distances, as in hundreds of miles. If a foraging trip is relatively short, the returning parent might carry food in its bill. Think about the iconic image of a puffin with dozens of sand eels stuffed in its beak. However, when a parent has to fly a long way from the colony, the captured prey are carried in the

bird's crop, or they're actually digested and then regurgitated at the nest. Eventually, the chick is big enough to be left alone at the nest for a while. Both parents can fly off to hunt for food. They both return to stuff food into the mouth of their fat, insatiable baby. The chicks of some seabirds stay at the nest for months. In other types of seabirds, the little buggers quit the nest early and splash into the water, where they complete their development. Some species of the family Al-Sidi, for example, are precocial, and they leave the nest after only a day or two.

This is true for merlets in the genus Synthlibro-Ramphus. Once the chicks hop in the water, mom and dad take care of them there. The adorable floating family sticks together, splashing and diving through the waves. For seabirds in general, even after the young birds fledge, their parents may take. take care of them for a long time, a long time for birds anyway. We're talking three months, possibly six months. Frigot birds usually care for their offspring for over a year. That's longer than just about any other kind of bird in the world. But the time comes, eventually, for the happy little family to break up. The juvenile birds become independent and head out to sea. Like the manx

Shearwaters, I was talking about earlier, young seabirds often spend several years on the open ocean before returning to land. Historically, it's been hard for scientists to keep track of young birds during this period. The batteries on GPS trackers and geolocators still don't last quite that long. So there's a gap in the scientific knowledge of what young seabirds do and where they go in the first years of their life. Ornithologists call these the lost years. But scientists are getting better and better data all the time. Data from tracking devices has already revealed some amazing stuff about those lost years. For example, a study in 2006 on juvenile wandering albatrosses discovered that, in their first year, these birds traveled an average of 115,000 miles

in one year. That's 184,000 kilometers. That's more than four times the circumference of the earth. I'm lucky if I can register 10,000 steps on my Fitbit every day. It feels like most of my steps are taken between my computer and the fridge. 10,000 steps is about 4.5 miles, which, over a year adds up to about 1,600 miles, or 2,500 kilometers. So, an adolescent wandering albatross covers over 70 times more distance than I do in a year. I guess they don't call them wandering albatrosses for nothing. Albatrosses and most other seabirds come back to land in the same place they were born, or at least pretty close to where they were born.

They have an instinct to return to their natal colony. Some will make their nest only a stone's throw from the exact spot where they hatched, and they'll probably keep coming back to this same site for many years. Remember the term biologists use for this behavior? It's called natal philipatry. Bonded mates may go their separate ways in the non-breeding season, possibly ending up thousands of miles apart, but they can always find each other again by returning to their nest site.

And speaking of the non-breeding season, what do seabirds do when they aren't busy finding mates, incubating eggs, or raising chicks? Naturally, this varies by species, but most of them head to distant waters, far from the colony. They might disperse, or they might end up in more or less the same locations. They find places where food is a lot of, abundant, and where the weather maybe isn't so bad. Arctic turns are one amazing example.

This species makes an epic migratory journey every year. They breed in the Arctic and sub-Arctic, then they make an indirect serpentine journey south. They spend the northern winter in the waters around Antarctica. Round trip, this adds up to between 30,000 and 44,000 miles. That's 48,000 to 70,000 kilometers. Every single year. I told you seabirds are incredible. You resisted the idea. You didn't believe me, but I hope you're starting to.

Let's move on to talk about what and how seabirds eat. As a group, these critters eat a wide variety of prey, and they display diverse feeding behaviors. We can categorize these behaviors into several foraging strategies. There's surface feeding, pursuit diving, plunge diving, predation of higher vertebrates, and parasitism. Within each of these general categories, there are, of course, variations. And some seabird species use multiple foraging strategies. The first strategy is surface feeding. Some seabirds prefer to do this while flying. Frigot birds, many petrels, and storm petrels feed from the ocean's surface while in flight. Other surface

feeders do so while swimming around. They seize prey on the surface or dip their heads into the water to nab small critters. Gulls and Fulmars do this, as do some petrels, sheer waters, and prions. The second major foraging strategy is pursuit diving. These birds chase things around underwater. Penguins are pursuit divers, so are ox like puffins and meurs. These birds use their wings for propulsion. Cormorants chase fish around underwater too, but they propel themselves with their feet. Then we have the strategy of plunge diving.

Species in the family, Suladi, the Gannets and Bubis, are special. plunged plunged divers. They shoot like rockets from the air into the water, catching fish and other prey well below the surface. Tropic birds and some turns are also plunge divers. The fourth strategy is predation of higher vertebrates. Higher meaning reptiles, birds, and mammals, rather than fish. For example, scuas and some gull species are especially notorious for snatching up baby birds and other small animals. Paracetism is another strategy, cleptoparasitism, that is, when one bird steals another bird's lunch. Frigot birds and scuas are really good at being kleptos like this. And of course there's eating the eggs of other birds and scavenging for scraps

and whatnot. The point is there are many ways to make a living as a salty seabird. The actual diets of seabirds range from microscopic phytoplankton and zooplankton to small crustaceans to fish and squid. But how do we really know, for example, what a northern fulmar eats or a sooty shear water? It's difficult to observe this in the wild. One fun approach ornithologists used to study seabird diets is to examine bird barf. When captured by scientists, a seabird will some sometimes hack up its lunch, probably as an instinctual defense mechanism. But if the bird doesn't cooperate by regurgitating its last meal voluntarily, scientists can, with care to minimize the bird's stress and discomfort, of course, induce vomiting. This technique is called stomach

lavage. Sounds kind of nice, doesn't it? Lavage, like a fancy French procedure you'd get at the spa. Pardon me, madame, but would you care to schedule a stomach lavage for this afternoon? In reality, the scene isn't so fancy. Researchers insert a tube down the esophagus of the bird and squirt salt water into it. Then they tip the bird's bill into a barf bag and they now have a sample of what that bird has been eating. This method might sound harsh. But, A, remember that seabirds are really good at regurgitation. It's an everyday thing for many of them, at least when they're delivering seafood for their chicks. And B, ornithologists studying seabird diets back in the day used to just kill the birds.

I imagine if you could ask them, most seabirds would probably tell you that getting one's stomach flushed is significantly better than getting murdered. Lavage and other methods have revealed to us that seabirds as a group eat all sorts of critters in the sea. Because of their broad range of prey, these birds are important players in marine ecosystems. One type of seabird or another is involved at just about every level of the marine food chain, which is really a food web, right? It's more complex than a simplistic linear chain of the cormorant eats the big fish and the big fish eats the little fish. It's also important for us to think about

where and when seabirds hunt for prey. Most species will feed opportunistically, but they also have feeding areas they use consistently. These are highly productive areas in the ocean, places where currents and underwater topography might conspire to bring nutrients from the seafloor to the surface. Phytoplankton and zooplankton are dense in such waters. These tiny organisms support the local food web, including seabirds.

Some areas are productive only at certain times of the year. Others are more consistent. The continental shelf break, for example, is a place where many seabirds congregate to forage. This is where the relatively shallow continental shelf drops off like a cliff, and the sea beyond it is much deeper. Upwelling water at the break brings nutrients to the sun. surface, creating productive waters. Prey animals like squid might swim close to the sea surface only at night. For this reason, certain seabirds like petrels forage at night or during the dim hours of dusk and dawn. Nocturnal prey animals sometimes glow with bioluminescence, which probably makes them

easier for seabirds to catch in the dark. Vision is, of course, the most important sense for seabirds when hunting. But many of them can use their sense of smell, too, especially species in the order procellariformis, petrels, sheer waters, albatrosses, all those tube noses. Olfaction is one of their bird superpowers. Petrels, for example, can detect trace amounts of the chemical dimethyl sulfide. This is released into the air by phytoplankton when they're being eaten by zooplankton.

You and I can smell dimethyl sulfide too. It's sometimes called the smell of the sea. Some people would say it has an unpleasant odor. Unpleasant like, you know, the smell of body odor or black licorish. But I imagine that, to petrels, dimethyl sulfide smells like some kind of sublime potpoury of vanilla, coconut, chocolate, cinnamon buns, orange blossoms, and bacon. Petrels can zero in on specific areas of the ocean where this chemical is being released in large quantities. These tend to be highly productive areas, teeming with tons of slimy seabird snacks.

Studies of albatrosses have shown these birds can chase down the source of a scent that's as far away as 3.7 miles or 6 kilometers. That's a pretty useful adaptation for a bird that forages far and wide. over the ocean. Young albatrosses and other seabirds are way less efficient at finding and catching prey compared to seasoned adults. Youngsters have to hone their skills over time, so it's a good thing that they have long lives. Even when a seabird isn't having the best luck finding food on its own, it might score by just keeping an eye on other birds flying around nearby. If the latter start to flock more tightly to converge, it might be a signal that food is in the water below. The tendency of seabirds to follow other seabirds is called social attraction. I got to see examples of this behavior,

or a variation of it anyway, when I worked as a naturalist on cruise ships in Alaska. We were watching humpback whales feeding on fish in the deep fjords of southeast Alaska. Flocks of several gull species wheeled overhead waiting for the whales to surface. The giant beasts would explode out of the water every ten minutes or so, mouths wide open and full of water and fish. The gulls would swoop down by the hundreds to snatch any stunned fish they could get. The whales would soon disappear beneath the dark water again. The gulls went back to circling and waiting. We humans would try to use the gulls as an early warning system for where the whales would pop up next. After all, the birds had a pretty good vantage point from the sky.

If they suddenly all started flying in one direction, we would look in that direction for the whales. Sometimes that worked pretty nicely. But sometimes the gulls would make a sudden turn and frantically swoop in one direction, but the whales would come up somewhere completely different. The flock of gulls got it wrong. If just a few gulls imagined they saw something whale-like and started flapping towards it, that might trigger a chain reaction. The social attraction behavior in the rest of the gulls could kick in. The silly birds just couldn't help themselves. Or else they were just messing with us humans.

Maybe they were like, oh, you want to see some whales, do you? You like whales? You pay thousands of dollars to go on a cruise so you can eat some fancy dinners and see some whales? Okay, cool, yeah, yeah, I get it. I can respect that. So, anyway, there they are! Whales! Look over there! Quick! Let's all freak out and go over there! Nah, I'm just messing with you. I'm just playing. For real, though, you humans are a bunch of gullible dumb-dums. What are these accents? I don't know.

Ah, we're just having fun, guys. Birds like puffins, petrels, turns, penguins, and frigate birds can do some incredible things. They can dive deep or fly seemingly impossible distances. They can survive rough seas and violent storms. But as tough as they are, these birds are still vulnerable to many threats created by human actions. Almost half the world's approximately 300 seabird species are in decline. Their populations are dwindling.

In fact, seabirds are among the most threatened of all bird groups. The primary threats they face on land are invasive predators, disturbances at breeding colonies, light pollution, and diseases like avian influenza. At sea, many seabirds are threatened by direct competition with humans over fisheries. We are overfishing the ocean, reducing the food supply for the birds. Albatrosses and other seabirds also die by the hundreds or thousands as by-catch in fishing operations. The birds accidentally get hooked and dragged under water where they drown. Pollution and climate change, too, are major threats.

There's a lot we can talk about when it comes to the issue of seabird conservation. But I'll save that for another day and maybe spin it off into a dedicated podcast episode. For now, let's just take a moment to think about and appreciate the hundreds of millions of seabirds out there, at this very moment. They're out there soaring over the high crests of tropical waves, or plunging beneath polar ice, or sitting meditatively on their nests, fasting for days or weeks to protect their fluffy chicks from the wind and from predators. There are still many unanswered questions about the biology of seabirds. But what we do know, I hope you'll agree, is awe-inspiring and deeply fascinating.

It was hard to cut myself off when I was writing the script for this episode. I just had to stop at some point. There's just so much cool stuff to talk about when it comes to seabirds. So thanks for hanging out with me today to fill your brain with knowledge during this long episode. I hope you had some fun. If you're keen to learn more about seabirds, I can recommend a book by Michael Brooke called far from land, the mysterious lives of seabirds. I wouldn't say this is a book for casual reading,

but if you're really looking to dive deeper, so to speak, this is a good next step. The Science of Birds podcast is made possible in large part by the kind-hearted folks who support me through Patreon. A massive thanks, as always, to my loyal and lovely patrons. My newest patrons are Bruce Collins, Jens Jules Rood, Marta, Lainey Casper, Steph Till, Frank Sateel, Deb Meyer,

Chris Grogan, and John Landry. Bienvenido and much gracias to all of you. In other words, thank you. And no, I don't really speak Spanish. Just a little bit. If you, my friend, are feeling adventurous and you'd like to support the science of birds, you can check out my Patreon page at patreon.

slash Science of Birds. You can also shoot me an email if you have something you'd like to share with me, a comment about the show, or maybe you want to provide me with some of your own life history data. Or you want to tell me what you think about the smell of seabird guano. In any case, my email address is Ivan at Scienceofbirds.com. You can check out the show notes for this episode, which is number 77, on the Science of Birds website, Scienceofbirds.com.

This is Ivan Philipson, wishing you a fabulous day. Peace.