The Science of Birds - The Common Loon

Episode Date: January 13, 2022

This episode—which is Number 43—is all about the Common Loon, Gavia immer. People in Europe may know it as the Great Northern Diver.This bird is a symbol of the northern wilderness in North America. It’s closely associated with lakes and ponds in the boreal forests of the northern US and Canada.~~ Leave me a review using Podchaser ~~‍Links of InterestLoon scenes in the movie On Golden Pond [VIDEO]Why Hollywood Loves this creepy bird call [VIDEO]Loon Kills Bald EagleAnimation of Common Loon abundance across the seasons.Link to this episode on the Science of Birds websiteSupport the show

I first learned about the existence of the common loon the same way I learned about most of the important things in life, from pop culture. There's this movie that came out in 1981, on Golden Pond, starring Catherine Hepburn and Henry Fonda. I was five years old at the time. I remember almost none. nothing about the movie, except for some vague imagery of the setting, a summer cottage on a lake in northern New England. Mostly, I remember the characters seem to have a lot to say about the loons living on the lake. The movie shows footage of loons and also features the sounds of calling loons. As I remember it, Catherine Hepburn's character, Ethel, seems to talk about loons incessantly for pretty much the entire length of On Golden Pond.

The loons. The loons. They're welcoming us back. Oh, look, I've spotted the loons. Thanks to scenes like that, Catherine Hepburn won the Academy Award for Best Actress that year. Good for her. As far as I'm concerned, however, the real stars of On Golden Pond were the common loons. But did anyone give a loon an Oscar? Even for Best Supporting Actor? Nope. As usual, the birds got snubbed. The character Ethel in this movie was out of her friggin mind for loons.

And, you know, I don't blame her. The common loon is a magnificent bird. It really is something to get excited about. Hello and welcome. This is the Science of Birds. I am your host, Ivan Philipson. The Science of Birds podcast is a lighthearted, guided exploration of bird biology for lifelong learners. This episode, which is number 43, is all about the common loon, which bears the scientific name, Gavia Imer.

This bird is a symbol. of the northern wilderness in North America. It's closely associated with lakes and ponds, golden or otherwise, in the boreal forests of the northern U.S. and Canada. In Canada, the common loon is so well-known and well-loved that it was featured prominently on the country's gold-colored one-dollar coin. These coins were first minted in 1987. Today, the word loony is often used as the nickname for the Canadian unit of currency. The Canadian dollar is the loony. But why do we call these birds loons? It's hard to say, because the origin of this English name is uncertain. It might have come from Luma, an old English word meaning a stupid or awkward person. That's where

the word lummox comes from. And as I understand it, there's a related word, Lume, in Scandinavian languages, which means clumsy or lame. But that's kind of rude, don't you think? I mean, did some European person hundreds of years ago see a beautiful loon and then shout? Hey, everybody, look at that big black and white bird. Yeah, the one floating around on the lake. What a stupid-looking bird.

It's all awkward and lame. Ha-ha. I tell you, we got to come up with a name for it. A name that, like, really captures the essence of just how stupid that bird is. That may not be how it really happened, but to be fair, the common loon and other loons really are awkward on the rare occasions when they try to walk around on dry land. They're built for diving in water and for flying, not so much for walking. More on that later.

Other names for the common loon include ember goose, and in the Icelandic language, Himrimi, which means surf roer. Now we're talking. Surf Roarer is a cool name, and I think, a better-fitting one for this excellent bird. The other English name you'll hear used a lot in Europe is Great Northern Diver. That's also a good, no-nonsense name. The bird is great, it breeds in the north, and it dives. Great Northern Diver. That's the name you'll see in birdfield guides in the UK and elsewhere in Europe. Well, today we're going to stick with the North American name, Common Loon. Again, its scientific name is Gavia Imer.

And now it's time to immerse ourselves in the natural history of this iconic bird. Size and shape are the first key traits we'll talk about. A guy named William Wood wrote a book in 1634 called New England's Prospect. In it, Wood gives us the first recorded use of the word loon. And he also had this to say about what a loon looks like. Quote, the loon is an ill-shaped thing, like a cormorant, end quote. Wow, so this guy manages to insult both the loon and the cormorant in a single short sentence. An ill-shaped thing?

Seriously, did William Wood ever actually see a common loon? And side note, if you'd like to read the book New England's Prospect yourself, go to your local library and ask for it by its full title. Which is, and I'm dead serious here, this is the actual title, New England's Prospect, a true, lively, and experimental description of that part of America commonly called New England, discovering the state of that country, both as it stands to our new come English planters and to the old native inhabitants, laying down that which may both enrich the knowledge of the mind-traveling reader or benefit

the future Voyager. Sorry. I just love those ridiculous book titles from Ye Olden Days. Anyway, the common loon is a large water bird. Its body length ranges from about 25 to 36 inches, which is 65 to 9. 90 centimeters. Wingspans are between 51 and 65 inches, or 130 and 165 centimeters. Males are larger than females, up to about 27% larger, and body size varies a lot with geography across the species range. One time when I was in Iceland, I saw a dead, stuffed common

loon in a museum. I stood right next to it, and wow, I was impressed by how big it was. It was a beast. However, and this is true, it turns out that things look larger when you're closer to them. The common loon is vaguely duck or goose-like in shape. Thus the name ember goose, but loons are not in the duck family anatidae. Loons are only very distantly related to those familiar waterfowl, the ducks and geese. The loon has a stout neck attached to its ovoid or egg-shaped body. It has short, strong legs, and these are attached way at the back of the body. The feet are large and webbed.

Webbed feet and powerful legs are what the loon uses to propel itself through the water, on the surface or while diving. The position of the legs, at the back end of the bird, is optimal for swimming. It's like having a propeller at the back end of a boat, but there's a trade-off. That leg position severely limits the bird's ability to walk on land. And thus, the poor loon got named for the one thing that it sucks at. This would be like, instead of naming me Ivan, my parents named me sports. The common loon's bill is straight and tapers to a sharp point.

It's dagger-shaped. Bill length ranges from 2.5 to 4 inches, or 6.5 to 10 centimeters. This streamlined shape is great for shooting through the water like a torpedo, and the bill serves as an ideal tool for snatching prey underwater. In terms of color, the bill is black in the breeding season, but bluish-gray in winter. The black bill matches the common loons mostly black breeding plumage. But these birds also sport plenty of white accents. Its back and wings are bedazzled with hundreds of little white squares and spots.

and the black neck has patches of elegant vertical white lines, a larger patch that wraps around the back of the neck like a collar and a smaller one in front. The black parts of the neck can show some purple or greenish iridescence in just the right light. And I should mention that the chest and the belly are also a crisp white. Adult loons, both males and females, all have pretty much the same plumage pattern. Males may be larger, so there is sexual dimorphism in size, but not so much in terms of plumage. The only real bit of color on a common loon is in its eye. The iris is completely blood-red with a tiny black pupil.

If you've ever looked deeply into the terrifying crimson eye of a loon, you might suspect that this bird was a source of inspiration to that famous writer of horror fiction, H.P. Lovecraft. because Lovecraft lived in New England. New England, which also happens to be crawling with, that's right, common loons. Coincidence? But seriously, the red eyes of loons are striking. They're almost like gems or, I don't know, like hard candies.

Interestingly, they fade to more of a dull reddish brown every winter when the birds aren't breeding. At that time of year, common loons are a lot less glamorous overall. They're not as boldly patterned. On their upper parts, their feathers are gray or even a little brownish, and they don't have all those lovely white spots and squares. So that was a lot about what a common loon looks like. We'll move on to consider how this bird swims, flies, and yodels.

Yes, it yodels, and it wails, and we'll get to that. In the late 1700s, famous French naturalist Georges Cuvier came up with a Latin name for the common loon. He wanted to acknowledge the bird's talent as a diver, so naturally he assigned it the genus Urinator. Yes, Urinator, I kid you not. Even though this snicker-inducing word is a synonym for bedwetter, in Latin it actually means diver. Urinator has, in very various forms been used in the scientific names of other diving birds, such as the brown pelican and the common diving petrel. Urinator is no longer used in the name of our loon, much to the disappointment of everyone. But the common loon is an excellent diver. It displays many

adaptations for swimming and diving. It's streamlined bill and body, for example, and its oversized, flippy, floppy webbed feet. On the quiet lakes where loon spend their summers, most of their dives last for less than a minute. But more rarely, loons have been recorded making dives of five minutes or more, even up to 15 minutes. The common loon's heart rate slows down while it's diving. This, of course, helps to burn less oxygen. Another adaptation that helps with diving is the structure of the bones. Unlike most birds, loons have solid rather than hollow bones. A heavier skeleton allows a loon to stay underwater more easily. Remember that penguins, too, have solid bones like this,

and their hearts also beat more slowly during dives. Some biologists have hypothesized that the red eye color of the loon is yet another adaptation to diving, because they say red eyes help with underwater vision, somehow. But there doesn't seem to be any real scientific evidence for this. So perhaps the function of the common loon's blood-red eyes is simply to inspire horror novels and fuel the nightmares of small children. So while the common loon may suck at walking, it is awesome at diving. And it ain't so bad at flying either. This species has been clocked at flying speeds of up to 70 miles per hour, which is 113 kilometers per hour. The bird flaps its wings fast and furiously. It has to because those wings are relatively short and narrow, considering the bird's

overall length and its weight. In fact, loons as a group have some of the smallest wings for their weight of any bird. Remember that loons have those dense bones weighing them down, so that's part of the equation. This is why it can be quite an ordeal for a common loon to get from the water's surface into the sky. It can't just burst into the air the way a duck does. The loon needs a long runway to get airborne. It faces into the wind and propels itself forward by kicking hard with its feet. Even flapping its wings vigorously, the loon might splash along the water's surface for up to a thousand feet before finally getting into the air.

In flight, the common loon looks sort of hunchbacked. Its head and neck jut forward, positioned lower than the hump on the back. The large feet stick straight out the back. This all makes for a pretty distinct appearance, easily distinguishable from a flying duck or goose, for example. Needing that long runway to take off from the water obviously hasn't stopped the common loon from surviving and thriving for millions of years. But then, along come us humans.

We have to go and complicate things. We gleefully build paved roads and parking lots all over the place. This can be a big problem for a loon during migration, because the bird might mistake a wet road for a river or a parking lot for a lake. The exhausted loon comes down to rest on what it thinks is water, and then, uh-oh, it's sitting on the ground, it's stuck. It can't really get around by walking, and it has no watery runway to get airborne again. Sadly, if no kind-hearted people come to its rescue, this bird will probably die. Now we come to the vocal sounds of the common loon.

For many of us, we know almost nothing about this bird other than the fact that it makes beautiful sounds. The calls of loons have been the subject of songs, poems, and legends for millennia, and for good reason. There are several distinct call types given by the common loon. Let's start with the whale. The whale. call is thought to be used as a way for mates to stay in contact on their lake. The pair may also

use the whale when dealing with other loons encroaching on their territory. Here's another example of the whale. Loon calls like this often have that lovely reverberation effect when heard at a distance. The sounds carry a long way, sometimes for miles. This next call is the Tremolo. It seems to be used to express alarm or distress. After sunset and long into the night, common loons on a lake, common loons on a lake will often call together in a chorus. Here's an example of a chorus on Cranberry Lake in upstate New York.

It was recorded around 10.30 p.m. on a summer night. The call you'll hear in the foreground here is the yodel. Yodels are only given by males, either in choruses or in territorial disputes. Each male has a unique yodel, like a signature or fingerprint. Okay, here's the chorus. When it comes to sounds that evoke the northern wilderness, the nocturnal cries of the common loon are right up there with howling wolves. Understandably, loon calls are often described as mournful, unearthly, or haunting.

Maybe not haunting like spooky ghost haunting, but, you know, evocative and unforgettable. Hollywood loves to use the common loon's whale call all the time for pretty much any movie scene that's shot in nature. Hey, movie maker person, is your scene filmed in a jungle? Well, slap a loon call on there. The sound engineer pushes the loon button. How about a desert with no water in sight for days? Yep, the person. Perfect sound for that is a common loon whale. Push the loon button. The movie is set in Australia, loon.

Africa, loon. Antarctica, how about a loon? There was even a loon call used as a background sound for a setting on another planet in Avengers' Infinity War. Loons in space? Preposterous. I mean, everything else in that movie was pretty much 100.000. realistic up to that point, but it lost all credibility the moment I heard that loon. Now let's consider which birds are related to the common loon. Then we can look at this

species distribution, its habitat, and all that fun stuff. Gaviadi is the name of the loon family. It contains only five species. These birds may, at first glance, look like ducks or grebes. But we've learned time and time again on this podcast that ducks can be deceiving. Oh, wait, sorry, I misread my script here. It says, looks can be deceiving. Well, okay, sure. For the record, though, ducks can be deceiving.

I'm just saying. But the point is that the Loon family, Gaviadi, is not closely related to anatidae or podisipedidae, the families of ducks and grebes respectively. Believe it or not, loons are much more closely related to herons, storks, and penguins than they are to ducks or grebes. All five loon species are in the genus Gavia. The closest relative of Gavia Imer, our common loon, is the yellow-billed loon, Gavia adamsiai.

The yellow-billed loon breeds way up in the Arctic in North America and across northern Siberia in Russia. This bird looks a lot like the common loon, except that, well, of course, it has a yellow bill. As for where we find common loons, this species has a breeding distribution that spans the northern latitudes of North America. It also breeds in Greenland and Iceland. I find it really interesting that even though common loons breed in the far western reaches of mainland Alaska, we don't find them just across the Bering Strait in Russia. The two continents are separated by only about 50 miles, a distance that a common loon could easily cover in less than an hour, at least theoretically. And there should be some good habitat

over there for common loons. However, let's not forget that easternmost Russia is the kingdom of the yellow-billed loons. Maybe the yellow-billed loons keep the common loons out. I can imagine an adventurous common loon flying over and landing on a lake in Russia. Immediately a rough-looking gang of yellow-billed loons swims over to give our common loon a hard time. You're long way from your home, American loon. This country belonged to yellow bills. We have no place for you. We don't like your face.

Your bill, it is not yellow. Go back to USA. Back to your Mickey Mouse and how you. you say, Leonardo DiCaprio. And that, of course, was a flawless Russian accent. All joking aside, I don't know the real reason that common loons don't breed in Asia. I'm not sure anyone does. Maybe someone will figure it out.

In any case, the common loon is a migratory species. When autumn rolls around, these birds leave the inland lakes where they breed, and they head for coastal waters. These movements are generally southward. You can find loons in winter off the coasts of Norway, Sweden, the U.K., Ireland, all the way south to Spain. In North America, we find them on the Pacific and Atlantic coasts, as well as in the Gulf of Mexico. And although most loons move to coastal marine areas, some of them will hang around in freshwater habitats in winter. And speaking of habitat, let's circle back for a moment to look at the breeding habitat of the common loon.

In summer, breeding loons prefer large, deep lakes with clear water. Loons eat fish, so the lake needs to be teeming with small fish. And if there are some islands and little coves along the lake shore, all the better. Most of the Primo Loon Lakes are in the boreal forests of North America, but we also find loons on some mountain lakes at lower latitudes in the U.S. On a large, placid lake, surrounded by a deep green forest, the common loon is the apex predator. It's like the lion of this lacustrine ecosystem. You can probably guess that the word lacustrin means having to do with lakes.

I imagine fish in a loon-haunted lake must live in fear of those vampiric red eyes and that pointy black beak. The global population of the common loon is estimated at about 600,000 birds. The species is in the least concern category on the IUCN red list. So it's doing reasonably well on the global scale. It has a large range and a pretty stable population. However, and there's always a however, isn't there? Loons are sensitive to the water quality of their lakes and to the availability of their fishy prey. For decades, one of the biggest threats to the common loon has been water pollution.

More specifically, mercury poisoning. Mercury increases to unnatural levels in a lake affected by man-made acid rain. This heavy metal is toxic to fish and to loons. It accumulates in the bodies of loons, making them sick and or, causing them to have fewer surviving chicks. Because the common loon is affected so strongly by pollution, biologists consider this bird a bio-indicator for the health of lake ecosystems. If a lake or cluster of lakes supports a healthy population of breeding loons, all as well. The ecosystem there is probably relatively pristine, relatively healthy. But in places where loons have declined

in number, or their reproduction has declined, the birds may be telling us, indicating to us that something is wrong. The good news is that government regulation of industrial pollution in the U.S. and Canada has reduced acid rain, like big time reduced. We don't hear about the threat of acid rains so much anymore, do we? Again, acid rain is the main thing that leads to high levels of mercury and lakes. But ecosystems and loon populations are still recovering from the bad old days when acid rain was a major environmental problem. What do we call a bird or other animal that eats mostly fish? Well, the Latin word for fish is piscous. And you've heard of the astrological sign, Pisces, right?

Right? So if a plant-eating bird is a herbivore, then logically we would call a fish-eating bird a that's right, a minnow-muncher. Other answers we would accept are goby-gobbler and salmon swallower. And of course I just made those silly names up. The actual word is Pisivore. P-I-S-C-I-V-R-E. Pysivore. The common loon is piscivoris. The common loon is pyceivorous. It eats mostly fish, either in lakes or in coastal marine waters. Not just any old fish, though, our loon prefers to hunt smallish fish that have a spindle-shaped body. In other words, fish that look sort of like flattened footballs. Examples of freshwater fish would be bluegill, yellow perch, and pumpkin seed. Custations are also on the menu. The common loon will eat crayfish

in freshwater and crabs in the ocean. This bird is a visual hunter. A floating loon dips its head into the water to look around for any fish, sort of like it's snorkeling. This is why these birds prefer clear water, the better to see the fish down there. And the need to locate their prey visually is also why loons usually hunt in shallow water. When the hunt begins, a loon dives and propels itself underwater with a those large, webbed feet. It doesn't use its wings much at all. It can change direction

underwater abruptly to keep up with a fleeing fish. The loon uses its feet and tail like rudders to turn on a dime. Even though the bill of the common loon looks like a spear or a dagger, the bird doesn't spear fish to catch them. Instead, it simply nabs the fish between its upper and lower beak, like tweezers. Fish are usually swallowed underwater. To help move the fish along down into the gullet, the loon has some pointy projections called denticles on the roof of its mouth. These little spines face backward into the throat.

In the podcast episode I did on the penguin family, we talked about a similar situation going on in the mouths of those birds. As I mentioned, the common loon is usually the top of the top of the bird. predator in its lake. An adult loon is a large bird, and so it rarely has to worry about being attacked by other animals. In the winter, however, when loons are paddling around on waves in the ocean, some of them get snatched by the occasional rando shark. Loon chicks are another story. They're much more vulnerable. One of the primary predators of baby loons is the bald eagle. Eagles and loons occupy similar habitats in the summer. If large fish in the lake are in short supply, a bald eagle or a

pair of eagles might try to pick off some loon chicks for lunch. But common loon parents are fierce protectors of their babies. A couple of years ago, there was a grisly crime scene discovered on the shore of a lake in Maine. There was a dead eagle lying there near a dead loon chick. Foul play was suspected. Maybe a person had illegally shot the eagle. So a game warden collected the deadbirds and took them to a veterinarian for examination. An x-ray of the bald eagle revealed a puncture wound in its chest that went all the way into the heart. Investigators came to the conclusion that the eagle had grabbed the baby loon in its talons. But before the eagle could get away, one of the adult loons shot up from underwater and stabbed the eagle in the heart with its dagger-like bill.

Wow, how crazy is that? In this instance of mortal combat between two national icons, Canada wins and America loses. The common loon may not spear fish with its bill, but I guess it does spear eagles. The breeding system of the common loon is serial monogamy. Loon's pair up and raise chicks together. The bond between a pair lasts, on average, about five years. But some pairs have stayed together to raise brood after brood for over 15 years. The two members of a bonded pair spend only the breeding season together.

They go their separate ways in winter, reuniting on their same territory the following summer. It seems commitment in these birds is more to the territory than to the mate. For example, let's say a female returns to her breeding lake in spring, but her partner from last year never shows up. She's not going to go to the ends of the earth to find her lost lover. She's not going to file a missing person's report. her motivation is to stay in what she instinctively knows is a high-quality territory, a nice lake with lots of fish and good nesting habitat.

Another male soon arrives on her lake. The female is probably going to just shrug her shoulders, say, and then pair up with this new guy. In any case, when two adult loons do pair up, they go through a series of courtship behaviors. These include some synchronized diving, circling each other while swimming, flicking their bills in and out of the water, and bowing their heads. Often when we say a bird species is monogamous like this,

we do so with a little asterisk at the end of the word monogamous. This species is monogamous, asterisk, an outward appearance only, wink, wink. These so-called monogamous birds might mate on the side with individuals other than their partner. Shananigans of this sort are common in birds, especially songbirds. If your human sense of propriety makes you offended by bird infidelity, you might be happy to hear that the common loon is an exception. It seems these birds never mate with anyone other than their bonded partner. So there are no extra pair copulations and no extra pair fertilizations. This was confirmed by a study published in in the journal Behavioral Ecology and Sociobiology.

The researchers collected blood samples from adults and chicks in 47 loon families from Wisconsin, Minnesota, and Michigan. There were a total of 58 chicks. Genetic testing of DNA from the blood samples revealed that every chick in those 47 families was 100% the offspring of the two parents raising it. In other words, there was no genetic evidence of any matings on the side. These birds are both socially monogamous and sexually monogamous. One possible explanation for why common loons are so faithfully monogamous is that the pair need to stay physically close together and work together to defend their territory from interlopers. The territory might be an entire small lake, a close,

cluster of small lakes or part of a large lake. Territory holders aggressively chase off any other loons that come slinking around. Territorial battles between loons can get pretty intense, even fatal. When two males face off, they might yodel at each other loudly. An aggressive male will often lift himself high in the water and spread his wings in an intimidating display. A couple of these upright display postures have names. Ornithologists call them the vulture posture and the penguin posture. And this reminds me of kung fu movies with the different fighting styles, you know, like tiger style and monkey style. So one loon facing off against another might say, ha ha, your penguin style is no match for my vulture style.

But for real, these birds can injure or kill each other with their stabby beaks. Let's not forget what happened to that bald eagle. When they aren't trying to kill each other, loons eventually get around to making a nest and laying some eggs. The nest is a simple mound of plant material. It's built on the ground on the lake shore, or sometimes the nest is surrounded by water on a tiny island. Clutch sizes are small, typically two eggs, but less often just one. When the baby loons hatch, they are covered in fuzzy black down. Like ducklings, loon chicks are pretty active within an hour after hatching.

And they typically leave the nest on day one. For the first week or so, the little fuzz balls right around on their parents' backs. And this is just too much, really. It's one of the most absurdly cute things you'll ever see in the world. world of birds. Seriously, look up some photos of baby loons and you'll see what I'm talking about. Young common loons remain dependent on their parents for food for a couple months. The adults take turns diving to catch tiny fish to feed to their babies. Eventually, the youngsters can be left alone to float on the surface while both parents make foraging dives. The chicks gradually

learn to dive on their own and they themselves become skilled piscivores. Little minnow munchers. But after about 12 weeks, it's time for mom and dad to say say sianara to their offspring. They bail. Juvenile loons make their first migration on their own, sometime between mid-September and mid-November. They'll spend their first two years living in the ocean, just off the coast. But by their third spring, they return to inland lakes in the breeding season. On average, common loons don't breed for the first time until,

they're about six years old. So it's a good thing these birds have long lives. From what we know, they can live for up to 30 years, perhaps even longer. They have time to find a good lake to settle down on, where they can wail and yodel their hearts out all night long. Thank you for joining me today to learn about Gavia Imer, The bird, formerly known as urinator, but known these days as the great northern diver, the surf roerer, the common loon. I hope you get to see one of these birds in the wild soon.

But if you don't live in loon country, I definitely recommend watching some YouTube videos about these birds, or even just looking at some photos. They're beautiful, they're elegant and fascinating. A heartfelt thanks, as always, to my supporters on Patreon. You guys are making a big difference in making this show possible. The newest members of my Patreon team, my newest patrons, are Ian and Karen Dias, Cindy Ann Bowers, and Kai, aka Nanonaturalist. Welcome and thank you. If you, dear listener, are just wishing there was a way you could support this podcast,

I have good news. You too can become a patron of the Science of Birds. Just go check out my page. Patreon page at patreon.com forward slash science of birds. And hey, send me an email if you have something you'd like to share with me. Maybe your thoughts about the podcast, or about an experience you've had with the loon, or about your kung fu fighting style of choice. Whatever it is, you can tell me by writing to ivan at scienceofbirds.com.

You can check out the show notes for this episode, which is number 43, on the science of birds website, scienceofbirds.com. This is Ivan Philipson, wishing you well, and I'll catch you next time. Peace.