A Deep Dive Into the World of Pelicans
I love watching a group of Brown Pelicans fly in formation over the ocean. With their huge wingspans, they glide easily and flap infrequently. As they float down to cruise just inches above the water’s surface, they make use of ground effects to increase their flight efficiency. They make it look almost effortless.
Their appearance recalls something prehistoric—with their long bills, chunky bodies, and expansive wings. But these Brown Pelicans are actually small for their kind. Most other pelican species are three or four times larger. Those guys look even more like something out of the Lost World.
And when dozens of Brown Pelicans are diving like torpedoes into the waves to catch fish—wow! What an amazing thing to see.
As a kid growing up in southern California, I sort of took these birds of the coast for granted. And I just assumed that all pelican species were plunge divers like the Brown Pelican and that people everywhere got to see this behavior.
I wasn’t alone in having misconceptions about pelicans. It turns out that there are several persistent myths about these birds. Maybe you’ve heard some of them, or dare I say, even fallen victim to believing them.
Well, today we’re going to get pelicans all sorted out. We’re going to shine the light of science on these wonderful animals and learn about their unique anatomy, their behavior, and more.
What's Special About Pelicans? Their Key Traits
Pelicans are large waterbirds, familiar to people in many parts of the world. Since most pelican species are big, whitish, and oval-shaped you might mistake one for a swan or goose from a distance. But seen up close a pelican is unmistakable. It’s long bill and throat pouch, technically gular pouch, are dead giveaways.
The pouch is made of stretchy, featherless skin. It hangs like a hammock from the lower jaw. This unique feature works like a basket—or really more like a fishing net—that enables a pelican to scoop up fish. No other group of birds feeds quite like this.
Those of us who live in North America are perhaps most familiar with the Brown Pelican and its feeding behavior. This species is famous for its dramatic plunge dives.
All pelicans have relatively short legs with fully webbed feet. And I mean fully. All four of their toes are connected by webbing. This type of bird foot is called totipalmate. Pelican legs, being stubby, aren’t great for walking. But those totipalmate feet make these birds really good swimmers. Duck feet, by contrast, and which you may be more familiar with, have only three toes connected by webbing. That’s just plain ol’ palmate.
Given that they eat fish and swim well, it’s no surprise that all pelicans spend most of their time on or near water. Some species are coastal, others live mostly on inland waters.
In these habitats, they tend to spend time together in groups. Whether in breeding colonies or while out foraging for fish, these are gregarious birds.
You can often find dozens of pelicans loitering around on beaches, mudflats, or river banks. Such places are called ‘loafing sites’. Seriously, they’re called loafing sites or loafing platforms. Loafing sites are places where water birds just hang out in their idle time, to rest, preen, vape, or whatever between bouts of feeding.
Most communication between pelicans is visual, rather than based on sound. They lift and wave their wings and snap their bills at each other. Adult birds can make simple calls, like grunts and hisses, but most of these are used only within a breeding colony. In other situations, pelicans are generally silent.
The Pelican's Bill and Throat Pouch
The beak—the bill—of a pelican is the longest of any bird. Specifically, the Australian Pelican is the world record holder. The male of this species has a bill up to almost 20 inches long, about 50 cm. No bird bill is longer. If we’re looking for the longest bird beak in the world relative to body size, then the trophy goes to the Sword-billed Hummingbird.
The upper bill of a pelican is mostly flat, with a broad, rounded tip. It's not as broad and rounded as the beak of a spoonbill, but it’s getting there. Its shape is closer to a type of short sword used by the Ancient Greeks. The blade was called a xiphos. The upper jaw of a pelican looks a lot like a xiphos. Another detail is that the pelican’s sword-like upper bill has a small, hard, hook-like projection at the tip. It’s called the nail.
The lower jaw, the mandible, is made of long bones that are amazingly flexible. The two halves of the mandible can bow outwards under pressure, which dramatically enlarges the opening into the gular pouch, technically gular pouch. More than once, I’ve come across a Brown Pelican skull on a remote beach in Baja California, Mexico. Holding the skull in my hands, I could bend each half of the mandible like the wood of a sapling tree, like a bow. It was really cool.
In the living bird, the distance between the two halves of the mandible is about 2 inches (5 cm) in the normal position. When bent outwards, that distance can be over 6 inches (15 cm). These bones bend passively when the pelican thrusts its open mouth into water. But a pelican also has some ability to actively, voluntarily expand the mandible using its pouch muscles or its jaw muscles.
The technical name for this jaw bending ability is streptognathism. This means “twisted jaw” in Ancient Greek. Pelicans aren’t alone in displaying streptognathism, but they give us perhaps the most dramatic example.
The remarkable pouch of the pelican dangles below the lower jaw. It’s elastic properties come from being infused with a matrix of collagen. It lacks feathers, and it’s riddled with blood vessels, so the pouch is highly vascularized.
Now we all know how a pelican uses its gular pouch, right? We just need to remember the old limerick that goes:
“A wonderful bird is the pelican,
His beak can hold more than his belly can,
He can take in his beak
Enough food for a week
But I’m damned if I see how the helican!”
While it’s true that pelicans are wonderful, and normally limericks are trustworthy sources of scientific information, this limerick is mostly fake news.
Pelicans do not store food in their gular pouches. This is one of the myths about pelicans: that they hold food in their beaks or their pouches for extended periods of time. It’s not a crazy idea, of course—it's fairly reasonable. It’s just not what happens. A pelican catches a fish and then swallows it in short order.
This is true even when transporting food to its chicks. Pelicans swallow a prey item first then fly back to the nest to regurgitate the partially digested food for their chicks.
In addition to blood vessels, the gular pouch has sensory nerves running through its stretchy skin. This is helpful for pelicans when they’re foraging for fish at night or in murky water. A pelican can feel a fish as it enters its pouch, then it snaps its bill shut.
And those blood vessels in the pouch provide an important mechanism for temperature regulation. Being large birds, pelicans can overheat more easily than small birds. By facing away from the Sun and fluttering its vascularized pouch, a pelican can shed heat to cool down. Heat escapes from the bird’s capillaries to the surrounding air.
This is similar to how the big, floppy ears of elephants work. An elephant is huge, so heat from its metabolism tends to build up in its body, escaping only slowly. Its ears have large surface areas and lots of blood vessels close to the surface. Just as gular fluttering dissipates heat in a pelican, an elephant can flap its ears to cool down. The reasons for this have to do with the physics of thermodynamics.
The gular pouch is such an important tool that a pelican takes care to keep its pouch in good working order. Pelicans have a regimen of stretching exercises to keep their pouches flexible and healthy.
How Pelicans Feed and What They Eat
All pelican species have more or less the same bill and pouch anatomy, the same basic structure. And they share the behavior of thrusting their heads into water to scoop up fish or small animals in their pouches.
When catching prey underwater, a pelican’s gular pouch balloons dramatically with the force of the incoming water. A Brown Pelican can take in about 2.5 gallons of water in one go. And an Australian Pelican can take in about 3.5 gallons, or 13 liters!
When a pelican is successful, its prey comes rushing in with all that water. The top of the bill snaps shut and the flexible mandible bones return to their normal position. This closes the opening of the pouch, trapping the prey.
The pelican then presses the big water balloon of its pouch against its breast to expel the water through the narrow opening of the bill. With an upward toss of its head, the pelican swallows the prey animal in one big gulp. All of this takes between 15 seconds and maybe a minute or so.
Brown Pelicans feed on small, schooling fish in shallow coastal waters. While circling in the air over the sea, a Brown Pelican begins a plunge dive sequence when it spots some fish below. This can start from as high as 65 feet (20 meters) above the water’s surface.
The pelican dives down head first. It pulls in its neck so that its head sits over its shoulders. It pulls its legs forward and folds its wings back at the wrist. Just before hitting the water the pelican lines the fish up along its bill, like using the sight on a rifle barrel.
The bird also twists its body to the left at the last moment. The pelican hits the surface at speeds up to 40 miles per hour. As its long bill pierces the water it throws its wings and legs backward while striking forward with its head, like a snake. The movement of the wings and legs here probably gives some extra acceleration to the head. The gular pouch expands and fills instantaneously with water.
If our pelican aimed correctly and everything went according to plan, it successfully captured one or more fish in its enormous gullet. Just how often are Brown Pelicans successful at this? Many years ago, my ornithology professor in college told us about a study that addressed this question. The researchers in this study observed Brown Pelicans feeding in Santiago Bay, on the tropical west coast of Mexico.
Over a couple days they recorded 2,449 plunge dives. They calculated that adult pelicans were successful in 84% of their dives. Immature birds weren’t quite as skillful. They came up with a fish only 75% of the time.
I remember this study mostly because my ornithology professor said it involved his idea of the perfect field work. The researchers, he told us, sat on that beautiful beach in Mexico, lounging with their toes in the sand. They drank ice cold beers as they counted pelican after pelican diving into the turquoise waves.
So these pelicans are smashing into the water again and again day after day. The forces involved could be destructive to the delicate tissues of a bird. But pelicans have been doing this for millions of years. It’s no surprise then that they have a suite of adaptations that minimize any negative impacts.
Looking at these adaptations, we can return now to that whole “I’m a pelican and I rotate my body to the left on impact” situation. The best explanation for why Brown Pelicans twist to the left is that the birds are protecting the soft tissues of their trachea and esophagus. These structures are always positioned on the right side of a Brown Pelican’s neck.
Another adaptation that provides protection is a system of air sacs beneath the pelican’s skin. These are concentrated on the bird’s underside. They act like airbags in a car to cushion the impact. Most birds have air sacs, but these are a bit more specialized for plunge diving. Air sacs in pelicans make them extra buoyant too, so these birds can’t dive very deep. They float like inflatable pool toys.
In your travels, you might have been told by someone that Brown Pelicans often die of starvation after going blind. They go blind—these people will tell you—because the birds sustain damage to their eyes after so many impacts with the water. It’s another myth about pelicans, a meme that just won’t go away.
Pelicans have been pelicanning for millions of years. If any of them ever went blind from diving too much—well, those guys were likely removed from the gene pool long, long ago. The pelicans that delight us today are the hardened survivors… those that natural selection has endowed with adaptations for their unique feeding strategy. As yet another example of such an adaptation, the third eyelid of the pelican—the nictitating membrane—closes over the eye to protect it at the moment of impact.
So if you’re going to worry about pelicans, don’t worry about them being blinded or otherwise harmed by going about their normal daily routines. Worry instead about the harm that humans do to them.
A very different feeding strategy is used by several of the larger pelican species, including the American White Pelican, Australian Pelican, and Great White Pelican. These birds often work together with other members of their species to catch prey.
These species rarely if ever plunge dive. Instead, they feed while paddling around on the surface of inland water bodies or shallow coastal waters. Sometimes they feed alone or with a buddy or two. But at other times, they coordinate their feeding with 10, 50, or even well over 100 other pelicans.
In the most impressive displays of coordination, American White Pelicans gather in groups of up to 30 birds, forming a semicircle on the water. They synchronize their bill dipping movements and herd schools of fish toward shore or into the center of the circle as it closes in. These events are called “fish drives.” They can last up to 10 minutes or so.
These coordinated semicircles of pelicans have the highest rate of fish capture per bird. That’s when compared to pelicans fishing on their own or in less well-organized groups.
Pelicans are vulnerable to something called kleptoparasitism. You might have heard of kleptomania, a disorder where a person can’t keep themselves from stealing stuff. Kleptoparasite animals are those that steal their lunches from other animals, rather than doing the hard work of catching their own food.
Gulls and terns of several species follow pelicans around and try to steal their catches. Gulls sometimes perch on the heads of a pelican that has just caught a fish. As the pelican is draining water from its gular pouch, the gull tries to snatch the fish.
In North America, Heerman’s Gull is a particularly notorious klepto. These gulls actually time their migrations to coincide with the movements of Brown Pelicans. Heerman’s Gulls chase pelicans around, harassing them and trying to steal their hard-won catches.
But pelicans sometimes flip the script and act as kleptoparasites themselves. They try to steal snacks from other pelicans or other bird species. For example, the Australian Pelican regularly kleptoparasitizes cormorants.
Eating More than Just Fish
So far, we’ve been imagining pelicans as scooping up fish. That’s fine because they do indeed eat mostly fish. But most pelicans will eat other creatures too. Aquatic critters like crayfish, crabs, turtles, frogs, and salamanders are on the menu for most pelicans.
Other birds are eaten, too. Particularly nestlings of other species. You might want to watch a BBC video about Great White Pelicans eating Cape Gannet chicks in South Africa. I’ll warn you that—despite the soothing narration by David Attenborough—this video might be upsetting. I mean, poor little gannets.
There are accounts and videos of pelicans eating gulls, ducks, and pigeons. There’s also a rumor that pelicans have even eaten small dogs. Even though this scenario is plausible, I’m a bit skeptical about it, since I haven’t found any solid evidence. So any story about a pelican scarfing down a chihuahua might need to be relegated—at least for now—to the category of urban legend or myth.
When it's time for pelicans to get together to make more pelicans, they often do so in large breeding colonies. Hundreds or thousands of pelicans congregate in places like small, rocky islands where they’re relatively safe from ground-dwelling predators. Some species nest on the ground, others make stick platforms in trees.
The sexes are very similar. During the breeding season, both develop bright colors on the bare skin of their faces and gular pouches. American White Pelicans also develop prominent horns on their bills. Also called knobs or epidermal plates, these structures are flattened from side-to-side, sort of like a dolphin’s dorsal fin. These horns are shed after the breeding season.
Adults pair off and display their colorful pouches during courtship. Pelicans are monogamous but only for one season at a time. They find a new mate each year.
It’s typical for pelicans to lay 2-3 eggs. These are incubated under the webbed feet of the parents. Both parents care for and feed the chicks.
Pelican chicks sometimes show weird behavior after being fed by their parents. The chick cries loudly, drags itself around by one wing, and bangs its head on the ground. This can even escalate into convulsions that look like a full on seizure. Appropriately, this behavior is called a tantrum. Ornithologists don’t know why these toddler pelicans act bonkers like this. Maybe it's to monopolize the attention of their parents, perhaps at the expense of their siblings.
In ye olden days, in Medieval Times, it was thought that a mother pelican was so dedicated to her attention-hogging babies that she would pierce her own breast to feed them her blood. Not true at all and no one knows how this conspiracy theory got started. It’s yet another myth about pelicans—one that I hope no one still believes.
Diversity, Distribution, and Evolution
The pelican family, Pelecanidae, includes only eight species. The Brown Pelican and American White Pelican are species in the New World. The only other species in this hemisphere is the Peruvian Pelican. Superficially, it looks a lot like the Brown Pelican and used to be considered a mere subspecies of the Brown Pelican. Now it flies proud as a bona fide full species.
The five remaining species are all in the Old World. We have the Australian, Great White, Pink-backed, Spot-billed, and Dalmatian pelicans. Dalmatian isn’t a color pattern; it refers to the historical region in Croatia called Dalmatia. Weirdly though, Dalmatian Pelicans don’t seem to be found in the Dalmatian region, at least not these days, according to data from eBird.
I also want to point out that in my Princeton field guide to the Birds of Europe, the Great White Pelican is described as having a ‘comical look.’ Even better, the Dalmatian Pelican is said to have ‘not so friendly a face.’
Other than the Brown and Peruvian pelicans, which have dark-plumage, pelicans are mostly white or light gray. They have black or dark gray flight feathers on their wings.
Pelicans are among the heaviest flying birds in the world. Only swans are heavier. Pelicans also have large wingspans, stretching to almost 11 feet in the Dalmatian Pelican. That’s pretty close to being the world’s largest wingspan. The Wandering Albatross has a slightly larger span at 11.61 feet or 3.51 m.
Even though the Brown Pelican is a big bird, it’s actually the smallest of the 8 pelican species. This species weighs 7 pounds or so. The Great White Pelican, by comparison, weighs up to almost 30 pounds (13 kilograms)!
As a group, the 8 pelican species are distributed across much of the world. You won’t find them in Antarctica, but they’re on all the other continents. They’re mostly confined to the tropical and temperate latitudes. And they’re absent from the interior of South America and from much of eastern Asia.
Pelicans feed and breed around water. The two chocolate-colored species—the Brown and Peruvian pelicans—are restricted to the marine environment. They live along shallow, near shore waters. The other species live mostly around inland waters: wetlands, estuaries, freshwater lakes, alkaline lakes, etc.
The oldest pelican fossils date to about 30 million years ago. These were found in France. And here’s a neat thing: the oldest fossil is a pelican skull and it has a beak remarkably similar to those of modern pelicans. So these birds have been scooping up hapless fish for over 30 million years.
This fossil data, combined with molecular genetic data paint a fairly clear picture that pelicans originated in the eastern hemisphere. The most likely scenario is that they spread to the western hemisphere in a single colonization event. Those pioneering colonist pelicans then evolved into the three New World species we have today.
The close relationship of the American White Pelican to it’s New World cousins is counterintuitive. If you were asked to classify the 8 pelican species based on appearance, you’d probably lump the American White Pelican with all of the Old World species and keep the two brownish species in their own group. But, as is often the case, the genetic data tells us the true story and helps us classify species based on their actual evolutionary relationships.
Genetic data has also helped us figure out which birds are the closest relatives of the pelican family. Once upon a time, back when I was in that Ornithology class, the pelican family shared the order Pelecaniformes with the frigatebirds, gannets, cormorants, anhingas, and tropicbirds. So those families were considered the closest relatives of pelicans. This grouping was based on mostly physical features. For example, these birds all have those fully-webbed totipalmate feet.
Based on genetic data, today the order Pelecaniformes is very different. Those other non-pelican families have been moved to other orders. They are replaced by the families of ibises, herons, the Hamerkop, and the Shoebill. The latter two species are actually the closest relatives of pelicans. Hamerkops and Shoebills are unique, stork-like water birds living in Africa.
Our classifications of birds and just about every other living thing keep getting rearranged and updated as we get more and more genetic data. That might annoy some people, but I love it! We’re getting closer and closer to unraveling the truth!
Just the other day, a new study was published in the journal Nature that reported we now have the whole genome sequences of 363 bird species. And importantly, this data set includes representatives of almost every bird family in the world. The Dalmatian Pelican, with its amazing wingspan and ‘not so friendly a face’ is currently the only pelican species with a fully-sequenced genome.
Pelicans face several threats from humans. As is often the case for birds, habitat destruction is high on the list of major problems.
Freshwater habitats, which pelicans depend on, are among the most threatened in the world. People routinely drain, pollute, or degrade wetlands in one way or another.
You may know that the organic pesticide DDT was an enormous threat to bird populations in the middle of the last century. Brown Pelicans suffered major losses because DDT in their environments caused the shells of their eggs to be too thin. A brooding pelican would just crush its thin-shelled eggs. Thankfully, Brown Pelican populations have rebounded since DDT was banned by most developed countries in the 1970s and 80s.
Oil spills can be devastating to pelicans. The horrific Deepwater Horizon event in 2010 caused huge numbers of Brown Pelicans to be covered in oil. It’s uncertain how many of them died, but at least 612 were cleaned up and released by kind-hearted rescuers.
Pelicans in marine and freshwater habitats can run afoul of fishing gear. They get tangled up in old nets or fishing lines, and may drown or starve as a result. Fisherpeople across the ages have persecuted pelicans, killing them outright. Some of them think that the birds compete with them for fish.
The Peruvian Pelican and Dalmatian Pelican are both categorized as Near Threatened by the International Union for the Conservation of Nature, the IUCN. The Peruvian Pelican depends heavily on vast schools of anchovies off the western coast of South America. The main reason this bird is in trouble is that humans are overfishing the anchovy populations.
The Dalmatian Pelican has lost its wetland habitats in many places across Eurasia. And this species faces several other threats, such as illegal shooting, disturbance of its nesting colonies, pollution, and collision with power lines.
And, of course, climate change looms large as a worldwide threat to pelicans. Their habitats are likely to dry up in some places as droughts become more severe. Warming ocean temperatures may cause fish populations to plummet on the coasts of North and South America. It’s hard to predict what will happen to pelicans as the climate changes. But most of what happens will probably not be good.
The Welcoming Wastes of a Bygone Age
To wrap up here, I’d like to share a lovely quote about pelicans from the pioneering conservationist Aldo Leopold. In A Sand County Almanac, he had this to say about some American White Pelicans:
“Let a squadron of southbound pelicans but feel a lift of prairie breeze… and they sense at once that here is a landing in the geological past, a refuge from that most relentless of aggressors, the future. With queer antediluvian grunts they set wing, descending in majestic spirals to the welcoming wastes of a bygone age.”