The Science of Birds - Mergansers

Episode Date: October 17, 2024

This is Episode 105. It’s all about a small group of birds called mergansers. These are diving ducks known for their skill at catching fish. They have long, slender bills with serrated edges, earning them the nickname "sawbills." Maybe you’re familiar with these birds. Maybe you’re already a big fan. Or maybe you didn’t know they existed until just now. Either way, our goal today is to learn a lot more about Common Mergansers and their close relatives. There are five species that we call mergansers. And there’s another species in this group that’s called the Smew. The Smew is sort of an honorary merganser. The six species we’re looking at today are divided among 3 genera. Of all the ducks in the world, mergansers are the species that depend the most on fish. So not surprisingly, they’re excellent divers and swimmers.  Links of InterestMerganser Duckling Swimming at High Speed [VIDEO]Red-breasted Merganser Courtship Display [VIDEO]Hooded Merganser Courtship Display [VIDEO]Hooded Merganser Chicks Jumping Out of Nest [VIDEO]Red-breasted and Common Mergansers herding fish [VIDEO] ~~ Leave me a review using Podchaser ~~Link to this episode on the Science of Birds website Support the show

Hello and welcome. This is the Science of Birds. I am your host, Ivan Philipson. The Science of Birds podcast is a lighthearted exploration of bird biology for lifelong learners. This is episode 105. It's all about a small group of birds called Morganzers. These are diving ducks known for their skill at catching fish. They have long, slender bills with serrated edges, earning them the nickname Sawbills.

When I think about Murganzers, the first thing that flashes in my mind, besides that thin, serrated beak, is the image of a common Morganser flying swiftly along the course of a small river, flying low just above the water, like it's on a very important mission and it ain't got time to waste. The common Morganser is large for a duck, and the male in breeding plumage is pretty unmistakable. He's got a white body with black accents, and his head is a dark, glossy green. Maybe you're familiar with these birds, too. Maybe you're already a big fan, or maybe you didn't even know they existed until just now. Either way, our goal, today is to learn a lot more about common Morgansers and their close relatives.

There are five species that we call Morgansers. And there's another species in this group that's called the Smew. That's S-M-E-W. The Smeu is sort of an honorary Morganser. The six species we're looking at today are divided among three genera. We'll talk a little more about that later. Of all the ducks in the world, Morganzers are among the species that depend the most on fish. So, not surprisingly, they're excellent divers and swimmers. There's this video, this meme, of what I think is a juvenile common Morganser. I've seen it pop up on YouTube and Instagram and whatnot. In the video, this person is holding the young bird in one hand.

They gently set it down on the bank of a river. As soon as it realizes that it's free, the little duck bolts into the water and takes off, paddling frantically like a speedboat along the surface of the water. It's gone in an instant. It's amazing and honestly pretty funny. I'll put a link to the video in the show notes. But yeah, it gives you an impression of how great Murganzers are at getting around in water. All right, let's go ahead and get into it.

First, we'll check out what Murganzers look and sound like. then we'll consider their diversity, distribution, and habitats. And much more! The body shape of a typical Morganzer is very much like your standard duck, but a few of them, especially the common Morganser, have bodies that are more streamlined, slightly torpedo-shaped, you might say. Two of the six species, the hooded Morganser and the Smew, have more compact bodies. These two birds are also the smallest in the group.

The larger Morganser species have some features that are convergent with those of other diving, fish-eating birds, like cormorants and loons. All these birds have a streamlined form and their feet are positioned, more or less, at the back of their bodies. Their webbed feet work sort of like the propeller of a boat. boat, propelling them through the water at high speed. But being awesome at diving and swimming comes at a cost. The posterior position of their feet makes Murganzers, loons, and cormorants

pretty useless for walking around on dry land. Grebes also fit into this category of aquatic birds that suck at walking. It's the beak of a Morganzer, however, that really sets it apart from other ducks. Let's take a few minutes to look at this thing. Unlike your classic spatulate bill of a typical duck, a Murganser's bill is long, slender, and hooked at the tip. It looks much more like the bill of a cormorant. But unlike cormorants and unlike loons,

Morgansers have wicked little teeth running along the inside edges of the upper bill and the lower bill. And when I said teeth just now, you probably couldn't see me making air-cans. quotes. Because we all know birds don't really have teeth, right? The way mammals and reptiles do? So in Murganzers, instead of calling the small hook-like structures running along the bill teeth, we should call them serrations. The red-breasted Morganser even has the scientific name Murgis serrator. The serrations of all Murgansers are made of the protein keratin, just like the

rest of the outer sheath of the bill. Remember that the general term for the keratin sheath of a bird's bill, its beak, is the ramphothica. Anyway, the serrated bill of Murganzers is, of course, an adaptation for catching and holding onto slippery fish. Murgis serrater, the red-breasted Murganser, is arguably the most highly adapted as a fish eater. It has the narrowest, most cylindrical bill of all Murganser species. Many other kinds of ducks have comb-like ridges of keratin on the inner edges of their bills. They're relatively blunt and rounded, however.

These structures are called lamelli. They're used by ducks as a sort of filter for feeding on tiny aquatic plants and animals. Most waterfowl have lamelli of some kind. So my guess, my hypothesis is that the serrations on the bills of Murganser, evolved from lamelli. In evolutionary biology terms, we'd hypothesize that Murganser serrations and the lamelli of other ducks are homologous structures, that they're both derived from a structure found in the common ancestor of these birds, even if they have different functions today. The classic example of homology in vertebrate animals is the forelim. The front limb or arm

of a mammal is homologous with a bird's wing. These two things, these appendages, evolved from the same original structure. But I'm not sure if ornithologists have really figured out that the serrations of our mergs are truly homologous with the lamelli of other ducks. It could be that these two structures evolved independently. The hooded Murganzer, which is the only species in the genus lophidites, has serrations that aren't all that sharp. The tooth-like structures on the bill of a hooded Murganser are more rounded or squared off. They're not so pointy. Compared to other Murgansers, the hoodie eats many more crunchy invertebrates, like aquatic insects and crayfish. So its bill may work a little differently. I mean, if you had to choose which kind of Murganser to insult or harass,

which species to incur the wrath of, my suggestion is that you go with the hooded Morganser. First of all, it's small and weak compared to most of the other species. And with those blunt serrations on its bill, a hooded Morganser almost never draws blood when it attacks and bites you in the arm or on the neck. It only pinches a little bit. You can just laugh it off. So you can go ahead and keep trash-talking the bird, insulting its mother and whatnot. without fear of repercussion.

Anyway, the tip of a typical Murganser's upper beak, the part we call the nail, is hooked. Again, this is an adaptation that helps with nabbing fish. In terms of bill color, three species have reddish-orange bills. That's true for the common red-breasted and scaly-sided Murgansers. The other three species have grayish-black bills. The common Murganser is the largest of the six species. Male common Morganzers are a bit larger than females at about 26 inches or 66 centimeters long. By comparison, your standard issue mallard duck is a few inches smaller than a common Murganzer.

The Brazilian Morganser is the next largest, followed by the scaly-sided Morganser. The smallest two species are the hooded Morganser, and the Brazilian Murganser, and the Brazilian Murgensur is the next largest, followed by the scaly-sided Murgensur. the smew. At only 16 inches or 40 centimeters long, the smew is the smallest of the bunch. Now, if you're looking at the silhouettes of Morganzers, there's another feature they share. They have a crest formed by feathers. Both males and females of all species have some sort of crest sticking up from their heads. The only exception, more or less, is the male common Morganser when he's in his breeding plumage. His glossy green head lacks a crest. But his girlfriend, the female common Morganser, has a totally rad crest all year long.

It's shaggy and spiky. Her head, including the crest, is rusty brown instead of green. Female Morgansors across the species have heads that are mostly reddish or brownish. But again, there's an exception. Female Brazilian Morgansers look a lot like their male counterparts. Both sexes of that species have dark plumage overall. and they have iridescent green heads and necks. They also both have crests, even though the males is actually longer.

As far as I know, Brazilian Murganzers have similar plumage in all seasons. But during the non-breeding season, males of most other species look a lot like the females. The grand prize for the most outlandish, most in-your-face head ornament has to go to the hooded Morganser. The male has a large, fan-shaped white crest that has a thick black border. Its feathers are dense and smooth-looking, with no visible gaps. If you look at him from the side, the male hoodie looks like he's got a massive, spherical head that's three sizes too large. But when you see him from the front or back, you realize it was all an illusion.

The bird's head, or at least his skull, isn't oversized. The crest is thin and flattened from side to side, like a punk rocker mohawk. The male hooded Morganser can raise and lower his crest, sort of like a traditional paper fan. When the crest is lowered, it lays mostly flat and trails out from the back of the bird's head. In that position, the large patch of white on the crest is shaped more like a triangle or rectangle behind the eye. The crests of the other Murganser species, by comparison, are kind of untidy and wiry-looking. Male Murgansers in general have breeding plumages with high contrast. Their bodies and wings have a lot of white, and their heads and necks are dark. Some, like the red-breasted Morganser, also have patches of reddish-brown feathers.

Another name for the red-breasted Morganser that it's probably safe to assume no living person on earth, actually uses anymore is C. Robin. Because, like the well-known European Robin, this Morganser species has a patch of reddish feathers on its chest. The aptly named scaly-sided Morganser has some cool-looking feathers on its flanks.

Each of the large overlapping feathers is white, but also has several thin, concentric black lines. The overall effect is beautiful, and it does look like fish or reptiles. skills. Now here's a quote for you. Few ducks are handsomer in life than a male American Morganser. That bold and potentially controversial statement is from the book, A Natural History of North American Birds of Eastern and Central North America, first published in 1925. And by American Morganser, they were talking about the common Murganser. That quote,

few ducks are handsomer in life than a male American Morganser is remarkably similar to the one that goes Few humans are handsomer in life than the male American podcaster Ivan Philipson That quote is from my mom So you can trust that it's completely unbiased and factually correct But yeah, the male common Morganser is a good-looking duck The female too is pretty easy on the eyes

with her shaggy ginger crest and blue-gray body. But returning to the hooded Morganser, to me that is the most beautiful, most handsomest of the Morgansers. The male is stunning. He's got that big crest, a black face and neck, and his eyes are bright yellow. Overall, his plumage is super high contrast and crisp looking. The back is black and the breast is white with two black stripes extending down the sides. His flanks are Rufus or tawny, with fine, wavy patterns of gray and black, while the

abdomen and undertale coverts are white. Pickax, Sheldrake. That's another old-timey name that probably no one uses anymore. It's an alternative name for the hooded Morganser. Pick-axe Sheldrake. That's pretty rad, you got to admit. I guess because the male's head looks sort of like a pick-axe, especially when he lowers his crest. And the word Sheldrake comes from Dutch and means a multicolored male duck. So you know what I'm thinking? If I'm ever the frontman for a punk rock band,

that should be my stage name. Pickax Sheldrake. And of course, as a punk rocker named after a Murganser, it would be mandatory that I have an epic white mohawk with a black border. Now, let us not forget our honor Merganser, the smew, Mergelis albelis. It's the smallest of the six species, right? Well, the male smew looks totally different from any other Murganser. He's mostly white with some bold black

accents. There are circular patches of black around the eyes that some say make the smew look like a cross between a duck and a giant panda. But when I look at a male smew, I think it looks way more like the duck version of an imperial stormtrooper from Star Wars. These aren't the droids we're looking for. Seriously, it's uncanny how much the smew looks like a stormtrooper. Look up some photos of the two side by side, and you'll see what I'm talking about. Right. Now it's time to listen to the beautiful melodies of singing Morgansers. Just kidding, these birds don't vocalize all that often.

And the sounds they do make are not musical. males make some calls during courtship when they're trying to impress females, and females sometimes respond during courtship with their own distinct calls. Both sexes make alarm calls, and these are mostly grunting sounds. For example, the following recording is a common Morganser, making what I think is an alarm call. Next, we have some red-breasted Morgansers recorded on the coast of Norway. It sounds like they're engaged in some courtship behaviors. The funny, sort of cat-like sound is the male.

In response, you might hear the female making a few soft calls. Now let's go over to the far north-eastern part of China. There we have the scaly-sided Murganzer, Murgis Squamatus. In this recording, I'm pretty sure what we're hearing is a female calling to her chicks. She's making a low, repetitive grunting call. You can hear the high-pitched squeaks of the ducs. mugglings as well. The Brazilian Morganser, Murgis octocetaceous, is the rarest merganser species in the world.

So not surprisingly, there aren't all that many recordings of this species vocalizations available. But I do have one for you, recorded in southeastern Brazil. A pair of Brazilian Morganzers are making contact calls to each other. So far, we've been listening to the vocal sounds of Morganser species in the genus Murgus. Birds in that genus are what we sometimes call the true Morgansers, again using air quotes. Then now we've got one more recording, and this one is from the hooded Murgensers. Murganser, Lophaditis, Cuculatus. So this is not one of the true Morgansers because it's in its own genus. In this recording, we're listening to a group of hooded Morgansers near the coast of Georgia

in the U.S. It's January, and these ducks are making courtship displays. The males produce a growling sort of call while making a display called the head throw, or buck. The male arches his back and throws his head back so that his beak is pointing up. We're hearing several males making their growling calls in this recording. All right, let's get into the geographic distributions of Murganzers, their migration patterns, and their habitats. But first, you know I got a geek out on the etymology of these bird names, on their origins. Just in case I haven't made it clear already, the bird.

Birds we're talking about today are ducks. They're all species in the duck and goose family, Anatidae. I covered that family in episode 18 of the podcast. But Morganzers and the Smew are different enough from other ducks that someone back in the day decided to give them their own name. And they're different enough that we're giving them their own podcast episode. The word Morganser originated with Latin, and it means diving goose. or plunging goose. The bird that we call the common Morganser goes by a different name in the UK and elsewhere in Europe.

English-speaking folks over there call it the gooseander. So just remember that the common Morganser and the gooseander are the same species. Now, what about the name Smew? That has to be one of the least flattering names for a duck, smew. It sounds to me like what we call a sticky, mucous-like substance. Maybe because Smew sounds like a mash-up, a portmanteau, if you will, of the words smear and glue. Smew. Anyway, for such a charming, beautiful bird, it doesn't have the best name. In my opinion. It seems the origins of the name Smew are sort of murky. It might

have come from a Dutch word meaning widgeon, which is another type of duck, or Smew might have come from a German word meaning wild duck. In any case, the genus name for the smew is Mergelus. That's a diminutive form of the word Mergus. So Mergelus sort of means a cute little Merganzer. And that, I would say, is spot on. The six species we're looking at today belong to a subgroup within the family Anatity. It's a distinct evolutionary lineage called Mergeny. That's spelled M-E-R-G-I-N-I. And I'm pretty sure it's pronounced Mergini. This group is usually called the Mergeny tribe. Tribe is a taxonomic unit that's more inclusive than genus, but less inclusive than family or sub-family. Birds in the tribe Mergini are often called sea ducks.

Other species in this group include the Iders, the skoders, the harlequin duck, the long-tailed duck, the golden eyes, and the buffalo head. Of all these sea ducks, the ones most closely related to our Murganzers are the two golden-eye species and the buffalo head. Those are the three species that make up the genus, Bousafela. The Smew, which is the only bird in the genus Mergelus, has sort of an intermediate position between Bousafela and Murgus. For instance, the Smeuse bill, with its hooked tip and serrated edges, is a feature shared with the Murgis Murgansers. However, the Smew's proportionately small bill and steep forehead are more similar to what we see in those Boussafala species. Moving on, let's look at the distributions

of Murgansers on the map of the world. Where are these birds found? Most of them are restricted to the Northern Hemisphere. That includes the Common Morganser, aka the Gousander, as well as the red-breasted Morganser, scaly-sided Morganser, hooded Morganser, and the Smew. The common and red-breasted Morgansers have vast distributions that span northern North America and Eurasia. The red-breasted Murganser breeds farther north than any of the other species. Some of its populations breed up in the Arctic. Maybe because of this far-north breeding, distribution, the red-breasted Morganser is one of the least studied ducks in North America, as in there's still a lot that ornithologists don't know about this bird.

The hooded Murganzer is basically a North American bird. It's found all over the eastern half of the continent and in the far western states. The Smew is restricted to Europe and Asia. Most of its breeding populations are in northern Scandinavia and Russia. The scaly-sided Morganser is found only in East Asia, Russia, China, North and South Korea, and Japan. So those guys are all in the Northern Hemisphere, but in the Southern Hemisphere we have the Brazilian Murganser in South America. But interestingly, there used to be at least a couple of Morganser species way down south in Australasia, in New Zealand to be more specific. But those species are sadly now extinct. We'll talk more about them in a little bit.

Some Morganser species are migratory, at least partially. The common and red-breasted Morgansers, for example, have some populations that are year-round residents while other populations migrate. The red-breasted Morganser generally migrates farther than any of the other species, but the Smew migrates pretty long distances as well. The scaly-sided Morganser is also a migratory species. These birds breed in the Russian Far East and North Korea and then spend the winter mostly in China and Japan.

The Brazilian Murganser is a tropical species that does not migrate. In terms of habitat, these are all aquatic birds, of course. You find one Murganser species or another in bodies of water like rivers, lakes, ponds, wetlands, bays, and lagoons. With only one exception, all Murganser species make their nests in tree cavities. So their habitat in the breeding season needs to include large mature trees, and those trees are usually near water. Common Murgansers prefer larger lakes and rivers in boreal and montane forests. Hooded Murgansers, on the other hand, hang out in

forested wetlands like swamps or beaver ponds with lots of trees around. The red-breasted Murganser is the one species that doesn't use tree cavities for nesting. So these birds are able to breed in far northern habitats like the tundra, where trees are pretty much non-existent. In the summer, red-breasted Murgansers are usually found in freshwater or brackish wetlands, not far from the ocean. The breeding habitat for the smew is lakes, ponds, and slow-moving rivers in the boreal forests and bogs of northern Eurasia. Last but not least, Brazilian Morganzers live year-round in clean, clear rivers flowing through tropical or subtropical forests. Naturally, all Murgansers need habitat that's teeming with lots of little fish and the other small aquatic creatures they feed on.

Scientists have used. used a combination of fossil data and genetic data to study the evolutionary histories of Murgansers. Fortunately for us, there was an important study about these birds published just a few months ago in the Zoological Journal of the Linnaean Society. A group of researchers, based in New Zealand and Australia, used genetic data from Murgansers to figure out the evolutionary relationships among all the species. Those relationships tell us something about when and where the species evolved. So a lot of what I'll be talking about regarding the evolution of Murgansers comes from this 2024 study. The lifestyle of pursuit diving, that is chasing fish around underwater,

seems to have evolved just once in the duck family. So once upon a time, there was a species that transitioned from being more of a grazing diver to a streamlined, fast-swimming fish-chasing duck. That species was the common ancestor of the six species we're talking about today. It lived roughly 20 million years ago, somewhere in the northern hemisphere. It was most likely a migratory bird that nested in tree cavities. So that was the origin of the Morganser lineage. Then the first to peel off and go its separate way, in the evolutionary sense, was the smew. So it's the most ancient, most divergent species of the six. Again, the smew is the only species in the genus Mergellus. The genus Lophodytes, that of the hooded Morganser, diverged from the rest of the

ancestral Morganser lineage around 18 million years ago. Between 11 and 9 million years ago, the remaining lineage diversified to give us all the species in the genus Murgus. This recent genetic study also gives us some insight into how and when some Murganzers ended up in the Southern Hemisphere. The researchers in the study were able to sequence mitochondrial DNA from museum specimens of the Brazilian Morganser and an extinct species from New Zealand called the Auckland Island Morganser. That DNA sequence data was then compared with data from the other living Morganser species, as well as a bunch of other sea ducks in the Murgonai tribe. This research suggests there were two independent colonization events,

occurring at least seven million years ago. The Auckland Island Morganser is most closely related to the common Murganser. So that tells us there was a colonization event where some common Morgansers, ended up in the New Zealand region, and the population they founded eventually evolved into a new species on the Auckland Islands. The origin of the other southern hemisphere species, the Brazilian Murganser, is quite different. That bird's closest living relative is the scaly-sided Murganser, which you might recall lives in the far east of Asia. Earlier I mentioned that the Brazilian Murganzer,

Murgis octocetaceous, is the rarest of the six species. Well, that species is actually one of the most threatened waterfowl species in the world. It's critically endangered. According to BirdLife International, there are less than 250 of these birds left on the planet. If you're trying to picture a Brazilian Murganzer, it's a dusky gray brown all over with a shiny green head and neck, and it's got a ragged crest hanging off the back of its head. This duck used to be more widespread in South America,

but today it survives in only a scattered collection of small populations, mostly in Brazil. A variety of human-related factors are driving Brazilian Morganzers towards extinction. These include dam construction, which obliterates river habitats, and deforestation. Another big threat is pollution from sewage, mining, and agriculture. Similar threats are faced by other Murganser species around the world. These birds need clean water in rivers, lakes, ponds, and coastal waters that are rich with healthy fish populations. Dams, deforestation, and pollution can all be devastating to Murgansers. The scaly-sided Murganser is also,

in trouble. It's listed as endangered at the global level. The estimate is that there are fewer than 5,000 of these birds remaining in East Asia. Scaly-sided Morgansers are suffering from habitat loss because of logging. People also hunt them illegally, trap them accidentally in fishing nets, disturb them with obnoxious motorboats, and so on. If we're not careful, we could lose these threatened Morganser species forever. already have a track record of killing off some Morganser species. One of them was the aforementioned Auckland Island Morganser, Murgis Australis. This species was still living on the Auckland Islands archipelago, south of mainland New Zealand, until the early 1900s. This species was killed off by

hunting and by the ravages of introduced predators, like cats and rats. There are still some museum specimens of the Auckland Island Morganser, so we not only have DNA from this species, we also kind of know what it looked like. It was about the size of a red-breasted Murganser. The male was pretty dark overall, with brown and blue-gray plumage. His head and neck were a dark reddish brown, and he also sported a short, shaggy crest. There was another species, the Chatham Island Murganser that was possibly a close relative of the Auckland Island Morganser. Several thousand years ago, humans appeared to have driven the Chatham Island Murganser to extinction. We know about this species, whose scientific name is Murgus Milaneri, only from a few fossils. It lived only in

the Chatham Islands, which lie east of mainland New Zealand. This bird was smaller than any of the other Murganser species we're talking about today. At this point in the episode, we all understand that Morgansers are fish eaters. They're specialized ducks honed by natural selection to be fish-chasing machines. Like cormorants, loons, and grebes, Murgansers are pursuit divers. Specifically, they're pursuit divers that propel themselves underwater with their feet. some other kinds of pursuit divers, like puffins and penguins, use their wings for propulsion underwater. Let's take a few moments to talk some more about the diet and foraging strategies

of Morgansers. The common Murganser, the gooseander, is perhaps the most familiar species for many of us. It eats mostly fish. Studies that have quantified the proportion of fish in the Common Morganser's diet, have found that it's somewhere between 50 and 90%. At least 50 fish species have been recorded in this bird's diet. The primary prey species include salmon, trout, suckers, sculpin, shad, sticklebacks, chub, and minnows. The specific types of fish eaten by common Murgansers vary depending on habitat, geographic location, and time of year. But the fish are generally small, typically four to 12 inches long, which is 10 to 30 centimeters. I just mentioned that trout and salmon are on the menu for these Murgansers.

Some people think that because they feast on young salmon, the birds can negatively impact salmon fisheries. You might recall that I talked about a similar conflict between humans and cormorants in episode 99. And like cormorants, Murgans. Morgansers have sometimes been persecuted and killed because of their supposed negative effect on fish populations. While predation by common Morgansers on salmon is a thing, the actual extent of their impact on salmon fisheries is mostly unknown. It's still up for debate. Variation across different ecosystems makes it difficult for scientists to generalize their findings. It seems that, yes, in some river systems Morganzers might play a role in limiting juvenile salmon populations, at least at a local

level. Meanwhile, in many other rivers, their impact is probably minimal compared to other environmental stressors. You know, stressors like dams, pollution, and overfishing by humans. In any case, it sounds like more research is needed on the question of how Murgansers affect commercial salmon fisheries. Anyway, that's fish. The rest of the common Morganser's diet is made up of invertebrates and amphibians. We're talking about critters like caddus fly and mayfly larvae, crayfish, and worms. The hooded Murganser also eats lots of fish, which make up roughly 45 to 80% of its diet. But compared to many of the other Murganser species, hoodies focus a bit more of their attention on aquatic invertebrates.

They're especially fond of crayfish. Something like 20 to 50% of a hooded Morganser's diet can be composed of crayfish and other freshwater crustaceans. All Murganser species use their muscular gizzards to grind up the bones and exoskeletons of their prey, often with some gravel in the mix to help with the grinding. But apparently the hooded Morganser has an extra thick, extra strong gizzard, which is probably useful for processing all those crunchy gizzard. crayfish. Morganzers of all kinds use their eyesight underwater to locate fish and other prey. Their eyes are well adapted to see underwater, with the ability to dramatically alter their focus

by changing the shape of the lens in the eye as they move from air to water. One common foraging technique is snorkeling. A Morganser paddles around on the water's surface with its face down in the water. It scans for the movement of prey below. The third eyelid, the nictitating membrane, is transparent. This membrane covers the eye underwater, protecting the eye while still allowing the bird to see, like swim goggles. Murganzers go on the hunt in other ways, too. They make shallow dives or deep dives, visually searching for prey out in the open.

Or a Murganser will poke around with its beak in holes and spaces between rocks on the bottom. This will sometimes spook a fish into revealing itself. And then the high-speed chase is on. And it takes a lot of little fish or invertebrates to fuel the energetic lifestyle and high metabolism of a Morganser. A red-breasted Morganser, for example, needs to eat about 15 to 20 fish a day. To meet that quota, the bird might have to dive up to 300 times

over the course of four to five hours. Another interesting foraging technique used by some Morgansers is cooperative herding. No, not herding sheep or cats, but fish. Of course. This is a behavior seen in red-breasted and common Murgansers. And maybe some of the other species do it as well. I'll read you an excerpt about this behavior from an observation published in 1965 in the journal The Auk. This observation was made in a bay on the west coast of Mexico. Quote, we saw seven red-breasted Morgansers

behaving in a manner that suggested they were fishing cooperatively. The seven birds were feeding in a shallow arm of the bay in water less than 24 inches deep on an incoming tide. They swam in a loose line, moving slowly, more or less in the same direction, with their faces either under the surface or above it for short periods of When a hunting bird discovered a fish, it immediately gave chase, flapping its wings and running on the surface. The positions of the fish were apparently determined by the birds peering under the

water at frequent intervals. As soon as one bird began a chase, the others joined in the pursuit, the nearby birds flapping and running along the surface, those more distant, flying. In the few seconds it took the last bird to arrive, a semicircle was formed by the birds with the pursued fish in the center of the ark. As the birds chased the fish, one or another of them dived under the surface in pursuit, surfacing at about the time the others reached that spot. This diving continued in each case until one of the birds caught the fish. Immediately upon surfacing, that bird would eat the fish. As soon as a fish was caught, the rest of the birds would begin to disperse and to hunt again. Occasionally, in the course of a chase, one or two of the trail,

birds would be distracted by the discovery of another fish, which they then chased. The secondary pursuits did not seem to be very successful. We saw no fish caught under these circumstances, while the cooperating group captured at least 10 fish in 15 minutes. End quote. I would love to see this behavior in person, but I found a short video that shows a mixed flock of both red-breasted and common Morgansers cooperatively herding fish in British Columbia, Canada. I'll put a link to the video in the show notes. Over in Europe, Smew form large flocks in winter, sometimes with thousands of birds. Groups of them will often dive in unison.

So perhaps this species engages in a little cooperative fish herding as well. Other types of birds take advantage of how Murganzers push fish closer to the water's surface during cooperative herding. Birds like snowy egrits, Bonaparte's gulls, and ring-billed gulls mill around at the water's surface waiting for their chance

to grab fish that Murganzers scare up. Or these non-Mirganzer birds will just try to steal any fish that a Morganser catches. Even bald eagles are guilty of this disgraceful thievery. But taking advantage

if other birds can go both ways. Morgansers will keep their eyes peeled for flocks of gulls that are making a ruckus where the gulls have discovered a big school of fish. The Morganzers then swim or fly over to get a piece of the action. This is kind of like me when I'm out walking aimlessly at a city park and I happen to notice some people gathered at a company picnic or a kid's birthday party. I slide over nonchalantly to the picnic table with all the potato salad, cookies, chips, and whatnot, and I can usually get my own piece of the action,

at least a few handfuls crammed in my mouth before someone sees me and realizes I'm an imposter. I run away before the cops show up, just like a Morganser paddling furiously across the surface of a river. When it comes to their breeding system, Murgansers are generally, generally monogamous. But males of most species abandon the females after the females begin incubation. And it's unknown how common it is for pairs to reunite in subsequent years. Male Brazilian Murganzers stick around, however. The male in that species protects the incubating female and then the hatchlings. The whole family stays together for months. Generally speaking, there's a fair amount of elaborate courtship behavior in these Morgansors when they first

pair up early in the breeding season. Males make courtship displays, and to a lesser extent, so do females. These behaviors involve various forms of neck stretching, head shaking, and head throwing, crest raising, and wing flapping. Male hooded Murgansers have one of the most elaborate courtship displays. They raise and fan out their impressive crests and shake them. During the head throw display, a male makes that low, frog-like, or growling call we heard earlier. I'll put a link to a video of hooded Morganser courtship displays in the show notes, so you can see these behaviors in action. They're pretty impressive and also pretty funny. Some Murganser species, like the common and hooded, do something called ritualized drinking during courtship.

Now, you might be thinking, yeah, ritualized drinking, like St. Patrick's Day, or at frat parties with the red solo cups and beer pong. But with Murganser's, ritualized drinking, also called ceremonial drinking, doesn't involve alcohol. It's a behavior with the birds greet each other. They dip their beaks and go through the motions of taking a sip of water from the surface of the lake or pond or whatever. Both males and females do this. Sometimes they do ritualized drinking just before mating, but it can also be used in other kinds of social interactions. For example, when new individuals join the flock.

Interactions among Morgansers aren't always about mating or about friendly greetings. Some species are highly territorial. This is true for the Brazilian and scaly-sided Morgansers, which, as you might remember, are each other's closest relatives. Breeding pairs of Brazilian Morgansers defend a year-round territory on a river or stream, and their territory can be pretty extensive, up to seven miles or 12 kilometers long. But it seems the other species are not so territorial. However, males can still be aggressive toward other birds that get too close to their mates or their nest sites.

As we touched on earlier, in almost all Murganser species, the nest site is a cavity in a tree. For example, the common Morganser often uses a hole originally carved out of a tree by a pilliated woodpecker. Or in Europe, the holes are often excavated by black woodpeckers. The height of the cavity can be up to about a hundred hundred feet. hundred feet off the ground, which is 30 meters. Less frequently, common Murgansers will make their nests in rock crevices, in dense vegetation on the ground, burrows in soil, or in old buildings. Several Morganser species will happily use artificial nest boxes. That goes for the common and hooded Morgansers and the smew. Only the red-breasted Morganser nests exclusively on the ground. These

birds make sure their nests are well-concealed and protected from the elements. So they place the nest in dense bushes, under driftwood on the beach, between boulders, etc. Apparently, there was even a case in the Arctic where some cheeky red-breasted Morgansers build their nest in an abandoned igloo. And that is just fantastic. Once the nest is ready, it's time to fill it with some eggs. Depending on the species, a typical clutch ranges from 8 to 13 eggs. But if you were to peek inside the nest of a common, red-breasted, or hooded Morganzer, it wouldn't be unusual to find a couple dozen creamy white eggs in there. So what's going on here?

Well, these Morganzers have no shame in acting as brood parasites, taking advantage of their own kind. When a female hooded Morganser, let's say, lays some eggs in the nest of another hooded Morganzer, that's called intraspecific brood parasitism. So that nest with a couple dozen eggs contains not just the eggs of the female who occupies the nest, but also some eggs from one or more of her neighbors.

They snuck in and dropped eggs when the nest owner wasn't looking. And sometimes the parasitic birds are ducks of other species. other Morganzer species, or even wood ducks or golden eyes. In the latter case, when the eggs in a nest are from more than one species, we call that interspecific brood parasitism. You know, like what cuckus do. I did a podcast episode all about that. Anyway, only the female incubates the eggs and takes care of the ducklings.

Because dad is a deadbeat. He took off already. Actually, it's probably not fair. to call the males deadbeats, because their behavior of leaving when incubation begins might actually have some adaptive advantages, not just for himself but for everyone in the family. For example, by leaving the nesting area, males might reduce the chances of attracting predators to the vulnerable nest and female, because males are way more conspicuous, right? In any case, mom incubates the eggs and then eventually, here come the duckling.

To the surprise of absolutely no one, baby Morgansars are insanely cute. They're precocial, which means as soon as they hatch, they're covered in fuzzy down feathers, and their eyes are open, and they're able to move around on their own. After hatching, the entire family abandons the nest within about 24 hours. When the nest is in a tree cavity, this exodus is one of the most astonishing and most adorable spectacles in nature. The chicks are able to climb up in the inside of the tree cavity to reach the entrance hole. They have long claws on their toes and stiff tail feathers to brace themselves against the wood as they climb. They clamber towards the light at the end of the tunnel.

Meanwhile, Mom is down on the forest floor, calling to her babies, encouraging them to leap out of the nest. Remember, the nest can be really high off the ground, so it's no small feet. for the baby ducks to make this jump. But each of them eventually does. For a few glorious moments, the sky is raining little fuzzballs. Each chick spreads its tiny wings and webbed feet in an effort to slow the fall. The chick weighs almost nothing, luckily, so it hits the forest floor and bounces once or twice without any harm. Sometimes the impact is also cushioned by a layer of fallen leaves or moss. There's a great PBS video showing some baby hooded Morgansers jumping out of a tree. I'll put a link to it in the show notes. It's hilarious. Once the Murganzer family is all

together on the ground, Mom leads the way to the water. They might have to trek for a mile or so before they reach a river or a lake. The babies stay close to Mom in the water. She's got a little entourage of fuzzy ducklings trailing out behind her as she swims. But there are usually a few of the little buggers riding high and dry on the mother's back, looking smug and making fun of all those losers who have to swim. The female's primary job is to protect her brood, since the youngsters can feed themselves. Their early diet is mostly aquatic insects and other invertebrates. They eat caddus flies, may flies, backswimmers, flies, water striders, and maybe a few seeds. Then, in most Morganser species, the ducklings switch to eating mostly fish.

In the common Morganser, for example, they start eating fish when they're about 12 days old. Sometimes you come across a female common Morganser or red-breasted Morganser, and she's got like 40 or more ducklings in tow. It's crazy. It could be that this is the result of that intraspecific brood parasitism we were talking about earlier. But there's another phenomenon that leads to this situation. It's called Cresh Formation or brood amalgamation. Cresh is spelled C-R-E-C-H-E.

At least with ducks like Morgansers, Cresh refers to a group of young ducklings that are cared for collectively by one or more adult females, not necessarily their biological mother. A few years ago, there was a female common Morganser in Minnesota who made the headlines when she was photographed with over 50 ducklings swimming in a line close behind her. It was ridiculous. There are probably multiple factors that lead to crash formation like this. One might be that some ducklings get confused and start following the wrong mom when two different

broods cross paths on the water. By the time a female realizes she's got a few extra babies trailing behind her, it's too late, or if she ever realizes it. In any case, the other female is long gone. Maybe this is like accidentally picking up the wrong luggage at the airport because it looks just like yours. Sort of like all those standard black suitcases on the luggage carousel, every baby Morganzer looks pretty much identical. The amount of time a female stays with her chicks varies. If she can dump them off into the care of another female, a mother might abandon her chicks after just a week or two. Otherwise, the family will most likely stick together for

some months. In the Brazilian Morganzer, where both mom and dad helped to protect the ducklings, the family may stay together for up to ten months. Some female Murgansers may return year after year to use the same nest cavity, and they may tend to breed not far from where they were born. For example, a study in Finland found that 127 out of 156 banded breeding female common Murgansers were recaptured at the study site in subsequent years. This suggests a high degree of breeding philipatry in female. Philopatry is spelled P-H-I-L-O-P-A-T-R-Y.

This is the tendency of a bird or other animal to return to or stay in the place where it was born, especially for breeding. Another study, using genetic data from DNA, also showed evidence of high levels of female philipatry in common Morgansers, this time in North America. And there's also some evidence of this behavior in red-breasted Morgansers. In terms of lifespan, Morganzers have been recorded living up to 13 or 14 years in some species. But those are the extremes. A typical Morganser in the wild probably has a significantly shorter life expectancy. As they try to survive from one day to the next, Murganzers must face the elements and the many threats imposed by humans. And of course, there are predators. Nest predators like squirrels,

Whirls, snakes, and raccoons eat eggs and chicks if they can reach the inside of the nest cavity. Adult Murganzers have many potential predators, both avian and mammalian. Birds of prey like deer falcons, snowy owls, and bald eagles will eat common and red-breasted Morgansers. The Brazilian Morganser can fall victim to raptors like Great Black Hawks and the Black and White Hawk Eagle. And an example that seems kind of wild to me, there's apparently documentation of killer whales, orcas, eating common Morgansers. Can you imagine seeing that? A Morganser is bobbing around on the surface of the ocean, minding its own business,

and then suddenly this enormous black and white sea monster shoots up from the deep to swallow the bird hole. Yikes! The ocean is spooky, you guys. And that is all I have for you today regarding the world's six wonderful Morganser species. Four in the genus Mergus, one, the hooded Morganser in the genus Lofodites, and the Smew in the genus Mergelis. I hope you've enjoyed learning a few things about these saw-build, pursuit diving, ritualized drinking, torpedo ducks.

That's a wrap on episode 105. If you want to learn about the entire duck family, remember to check out episode 18 of the podcast. I'd like to welcome the most recent recruits to my Patreon community. And to cite, Jamie Quaruchio, Taylor Mon, Peter D, and Joshua Achley. Thanks so, so much for becoming supporters of the show. And a big thank you to my entire Patreon community for making all of this possible. If you are thinking about becoming a supporter, you can check out my Patreon page over at

Patreon.com slash Science of Birds. There's also a support the show link in the show notes. And if you have some words you'd like to share with me, please go ahead and shoot me an email. Perhaps you'd like to offer a better common name for the Smew. You kind of can't go wrong, since just about anything would be an improvement over Smew. I'm going to go with Stormtrooper Duck. Anyway, my email address is Ivan at Scienceofbirds.com. It sometimes takes me a week or more to respond, but I try to get back to everyone who writes to me.

You can check out the show notes for today's episode, along with some curated photos of Morghant. on the Science of Birds website, scienceofbirds.com. This is Ivan Philipson. Thanks for listening and I'll catch you next time. Cheers.