Episode 278: Gender Diverse Animals

This week is Connor’s episode, and we’re going to learn about some animals that don’t conform to “typical” gender roles, one way or another.

I’ll be at ConCarolinas this week, from June 3 through 5, including recording a live crossover episode with Arcane Carolinas!

Further reading:

Species of algae with three sexes that all mate in pairs identified in Japanese river

How a microbe chooses among seven sexes

Facultative Parthenogenesis in California Condors

The sparrow with four sexes

Chinstrap penguins make good dads:

Laysan albatrosses make good moms:

Black swans make good dads:

Some rams really like other rams (photo by Henry Holdsworth):

New Mexico whiptail lizards are all females:

California condor females don’t always need a male to produce fertilized eggs:

Clownfish change sex under some circumstances:

The white-throated sparrow essentially has four sexes:

You are awesome (photo by By Eric Rolph)!

Show transcript:

“Hey y’all, this is Connor. Welcome to a very special Pride Month edition of the Strange Animals Podcast.”

This week we have Connor’s episode! We decided to make it the very last episode in our Kickstarter month so that it’s as close to the month of June as possible, because June is Pride Month and our episode is about gender-diverse animals! Don’t worry, parents of very young children, we won’t be discussing mating practices except in very general terms.

Pride month celebrates people’s differences when it comes to gender expression and sexuality. That’s why its symbol is the rainbow, because a rainbow is made up of all different colors the same way there are different kinds of people. Sometimes people get angry when they hear about Pride month because they think there are only two genders, and that those two genders should only behave in certain ways. Pffft. That’s not even true when it comes to animals, and humans are a lot more socially complicated.

For instance, let’s start by talking about a humble creature called algae. If you remember episode 129, about the blurry line between animals and plants, you may remember that algae isn’t actually a plant or an animal. Some species resemble plants more than animals, like kelp, but they’re not actually plants. In July of 2021, scientists in Japan announced that a species of freshwater algae has three sexes: male, female, and bisexual. All three sexes can pair up with any of the others to reproduce and their offspring may be male, female, or bisexual at random.

Even though the algae has been known to science for a long time, no one realized it has three sexes because most of the time, algae reproduces by cloning itself. The research team thinks that a lot of algae species may have three sexes but researchers just haven’t been looking for it.

Yes, I realize that was a weird place to start, but it’s also fascinating! It’s also not even nearly as complicated as a protozoan called Tetrahymena thermophila, which has seven sexes.

Let’s look at a bird next, the penguin. You’ve probably heard of the book And Tango Makes Three, about two male penguins who adopt an egg and raise the baby chick together. For some reason some people get so angry at those penguins! Never trust someone who doesn’t like baby penguins, and never trust someone who thinks animals should act like humans. The events in the book are based on a true story, where two male chinstrap penguins in New York’s Central Park Zoo formed a pair bond and tried to hatch a rock, although they also tried to steal eggs from the other penguins. A zookeeper gave the pair an extra penguin egg to hatch instead.

The most interesting thing about the story is that same-sex couples are common among penguins, in both captivity and in the wild, among both males and females. Since penguins sometimes lay two eggs but most species can only take care of one chick properly, zookeepers often give the extra eggs to same-sex penguin pairs. The adoptive parents are happy to raise a baby together and the baby is more likely to survive and be healthy. Occasionally a same-sex penguin couple will adopt an egg abandoned by its parents.

If you remember episode 263 a few months ago, where we talked about animals that mate for life, you may remember the Laysan albatross. In that episode we learned about a specific Laysan albatross named Wisdom, the oldest wild bird in the world as far as we know. While I was researching Wisdom, I learned something marvelous. As many as 30% of all Laysan albatross pairs are both females. Sometimes one of the females will mate with a male and lay a fertilized egg, and then both females raise the baby as a couple. Sometimes one of the females lays an unfertilized egg that doesn’t hatch. There are many more Laysan albatross females than males, which may be the reason why females form pairs, but it’s perfectly normal behavior. It’s also been a real help to conservationists. Sometimes an albatross pair will nest in an area that’s not safe, like on an airfield. Instead of leaving the egg to be smashed by an airplane, conservationists take the fertilized egg from the unsafe nest and use it to replace the unfertilized egg of a female pair. The egg is safe and the chick has adoptive parents who raise it as their own.

Many other birds develop same-sex pairs too. This is especially common in the black swan, where up to a quarter of pairs are both male. One or both of the males will mate with a female, but after she lays her eggs the males take care of them and the cygnets after they hatch. Cygnets raised by two dads are much more likely to survive than cygnets raised by one mom and one dad. The males are stronger and more aggressive, so they can defend the nest and babies more effectively.

Birds aren’t the only animals that form same-sex pair bonds. Many mammals do too. It’s been documented in the wild in lions, elephants, gorillas, bonobos, dolphins, and many more. In species that don’t typically form pair bonds, homosexual behavior is still pretty common. It’s so common among domestic sheep that shepherds have to take into account the fact that up to 10% of rams prefer to mate with other rams instead of with ewes. Some rams show attraction to both males and females. This happens in wild sheep too, where rams may court other rams the same way they court ewes. Some ewes also show homosexual behavior.

The New Mexico whiptail is a lizard that lives in parts of the southwestern United States and northern Mexico. It can grow over nine inches long, or 23 cm, and is black or brown with yellow racing stripes. It eats insects and is an active, slender lizard that’s common throughout its range. And every single New Mexico whiptail lizard is a female.

The lizards reproduce by a process called parthenogenesis. That basically means an animal reproduces asexually without needing to have its eggs fertilized. The lizards do mate, though, but not with males. Females practice mating behaviors with each other, which researchers think causes a hormone change that allows eggs to develop. Females who don’t mate don’t develop eggs.

Female birds can sometimes reproduce asexually too. It’s been documented in turkeys, chickens, pigeons, finches, and even condors. A study published in late 2021 detailed two instances of parthenogenesis in California condors in a captive breeding program. In both cases the females were housed with their male mates, and in both cases the pairs had produced offspring together before. But in both cases, for some reason the females laid eggs that hatched into chicks that were genetically identical to the mothers. It’s possible parthenogenesis is even more common in birds than researchers thought.

In many species of reptile, whether a baby is a male or female depends completely on how warm its egg gets during incubation. For example, the American alligator. The mother gator builds a nest of plant material and lays her eggs in it. As the plant material decays, it releases heat that keeps the eggs warm. How much heat is generated depends on where the mother alligator builds her nest and what plants she uses, which in turns affects the eggs. If the temperature in the nest is under 86 degrees Fahrenheit, or 30 Celsius, during the first few weeks of incubation, most or all of the eggs will hatch into females. If the temperature is 93 F or 34 C, most or all of the eggs will hatch into males. If the temperature is between the two extremes, there will be a mix of males and females, although usually more females.

Because climate change has caused an overall increase in temperatures across the world, some already vulnerable reptile populations, especially sea turtles, are hatching almost all males. Conservationists have to dig up the eggs and incubate them at a cooler temperature in captivity, then release the babies into the ocean when they hatch.

Other animals change from male to female or vice versa, depending on circumstances. The clownfish, for example. Clownfish start out life as males but as they grow up, most become females, although only the dominant pair in a colony actually reproduces. Clownfish live in colonies led by the largest, most aggressive female, with the largest, most aggressive male in the group as her mate. If something happens to her, her former mate takes her place, becoming a female in the process. The largest juvenile male then becomes her mate and remains male even though he puts on a growth spurt to mature quickly. If Finding Nemo was scientifically accurate, it would have been a much different movie.

Another group of fish that live around reefs are wrasses, which includes the famous cleaner fish that cleans parasites and dead tissue off of larger fish. Wrasses hatch into both males and females, but the males aren’t the same type of males that can breed. Those develop later. When the dominant breeding male of the group dies, the largest female or the largest non-breeding male then develops into a breeding male. But sometimes a non-breeding male will develop into a female instead.

The term for an animal that changes sex as part of its natural growth process is sequential hermaphroditism. It’s common in fish and crustaceans in particular. Other animals have the reproductive organs of both a male and a female, especially many species of snail, slug, earthworm, sea slug, and some fish. We talked about the mangrove killifish in episode 133, and in that episode I said it was the only known vertebrate hermaphrodite. That’s actually not accurate, although I was close. It’s the only known vertebrate hermaphrodite that can self-fertilize. Almost all mangrove killifish are females, although they also produce sperm to fertilize their own eggs. The eggs hatch into little clones of the mother.

We’ve talked about seahorses before too, especially in episode 130. Seahorse pairs form bonds that last throughout the breeding season. The pair participate in courtship dances and spend most of their time together. When the eggs are ready, the female deposits them in a special brood pouch in the male’s belly, where he fertilizes them. They then embed themselves in the spongy wall of the brood pouch and are nourished not only by the yolk sacs in the eggs, but by the male, who secretes nutrients in the brood pouch. So basically the male is pregnant. The female visits him every day to check on him, usually in the mornings. When the eggs hatch after a few weeks, the male expels the babies from his pouch and they swim away, because when they hatch they are perfectly formed teeny-tiny miniature seahorses.

Let’s finish with a little songbird that’s common throughout eastern North America, the white-throated sparrow. It has a white patch on its throat and a bright yellow spot between the eye and the bill. There are two color morphs, one with black and white stripes on its head, one with brown and tan stripes on its head. Both males and females have these head stripes. The male sings a pretty song that sounds like this:

[white-throated sparrow call]

A 30-year study into white-throated sparrow genetics has revealed some amazing things. The color morphs are due to a genetic difference that affects a lot more than just feather colors. Black morph males are better singers, but they don’t guard their territory as well or take care of their babies as well as brown morphs do. They also aren’t as faithful to their mates as the brown morph males, which are fully monogamous and are diligent about helping take care of their babies. Despite their differences in raising offspring, both morphs are equally successful and equally common.

All this seems to be no big deal on the surface, maybe just pointing to the possibility that the species is in the process of splitting into two species or subspecies. But that’s not the case.

Black morphs always mate with brown morphs. A black morph male will always have a brown morph mate, and vice versa. Genetically, the two morphs are incredibly different—so different, in fact, that they seem to be developing a fully different set of sex chromosomes. In other words, there are male and female black morph birds and male and female brown morph birds that are totally different genetically, but still members of the same species that only ever breed with each other. In essence, the white-throated sparrow has four sexes.

Usually I try to end episodes with something funny, but today I’m going to speak directly to you. Yes, you! If you’re listening to this or reading the transcript, my words are meant just for you. You are an amazing person and I love you. You deserve to be happy. If anyone has ever told you there’s something wrong with the way you are, or the way you wish you were or want to be, they’re wrong. They probably also don’t like penguins, so you don’t have to believe anything they say. If you’ve ever read books by Terry Pratchett, you may recognize this quote: “Be yourself, as hard as you can.”

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 127: New World Vultures

This week we’ll learn about some vultures from North and South America–some living, some extinct, and one mystery! Thanks to Maureen and Grady for their suggestions!

Thanks also to Kat White for the Turkey Vulture Song that opens the podcast! If you’d like to buy her album “In the Eye of the Owl,” visit her website at katwhitemusic.com/

Further listening:

CritterCast episode 35 Turkey Vultures

How to tell a turkey vulture apart from a black vulture:

The king vulture has a very bright head:

The Andean condor soaring:

The painted vulture:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

Way back in episode 40 we learned about the bearded vulture and some of its close relatives. This was a suggestion from Maureen, and I always meant to revisit vultures so we could learn about more vulture species. Then Grady wanted to know how long buzzards stay in the sky until they come down for food, and why do they soar for so long? That’s a great question that shows some good observation skills, so let’s go back to vultures and learn more about them.

Those of you listening in Europe may be wondering why I’m talking about buzzards in a vulture episode. That’s because we’re going to learn about new world vultures today, and in North America the general term for a vulture is a buzzard. In Europe, a buzzard is actually a type of eagle.

Before we get into the episode, though, I should mention that the intro music we heard is by Kat White, who was kind enough to let me use a snippet. It’s from the album “In the Eye of the Owl,” which is all about animals and so much fun I wanted to let everyone know about it. I’ll put a link in the show notes so you can find out more about the songs.

Kat also let me know about a turkey vulture named Lord Richard who lives in a park called Lindsay Wildlife Experience in California. Lord Richard just turned 45 years old and got a huge birthday party! So as you can see, vultures can live a long time in captivity, although usually not as long in the wild. Then again, the oldest verified vulture is an Andean condor born in captivity in 1930 who died in 2010 at the age of 79. Andean condors in the wild can live more than 50 years. This makes Lord Richard sound like a positive youngster.

New World vultures are native to the Americas and all of them are pretty big. In fact, condors are vultures and they’re extremely large birds. The New World vultures aren’t very closely related to each other but they all share some traits.

Vultures are scavengers that find dead animals to eat. The meat from dead animal carcasses is referred to as carrion. Vultures will also eat rotting fruit and garbage sometimes. Because they eat meat that is often spoiled, vultures have an extremely acidic digestive system that helps the bird digest its food quickly and kills off any bacteria that might make it sick. It also has beneficial bacteria in its digestive system that neutralize toxins.

But that’s not where the adaptations to eating carrion end. The vulture is a highly specialized bird. Most vultures don’t have many feathers on their heads, unlike other birds. If you’re snacking right now, you might want to pause this until you’re done. Quite often a vulture will actually stick its head into a rotting animal carcass to get at the, uh, softer parts. This means its head gets covered in rotting gunk and a lot of bacteria. If it had head feathers, they would be destroyed by bacteria.

One interesting thing about vultures of all kinds is that they actually help stop the spread of diseases like rabies and anthrax. Their digestive tract is so effective that it kills off viruses that caused the animal to die, so it’s actually beneficial to the environment in general and to farmers. Unfortunately, farmers don’t always know this and think vultures spread disease. Many vultures are protected species in most countries to stop farmers and other people from shooting them.

Quite often you’ll see a vulture perched somewhere up high with its wings spread. It does this to dry them when it’s been rainy or foggy, but also so that sunlight will help kill off any bacteria on the feathers. That’s another reason the vulture has no feathers on the head, so that sunlight can kill off any bacteria on its skin.

Vultures do some other gross stuff, like pee on their own legs. They do this to cool down in hot weather, since as the liquid droppings evaporate it cools the legs, and therefore cools the blood flowing through the legs, and therefore cools the vulture’s body temperature overall. But vultures also like to bathe in shallow water, which helps clean the skin and the feathers, and which of course washes any droppings off their legs.

Vultures also puke up what they’ve eaten if they feel threatened. This serves two purposes. The vulture is immediately much lighter and can fly away more easily, and the horrible stench of partially digested rotting meat may drive away a potential predator.

There are seven species of new world vulture alive today. The most common one is the turkey vulture, which lives throughout most of North and South America. The next most common is the American black vulture, which lives in South America up to the southern parts of North America. From a distance it can be hard to tell the two apart, but the black vulture has silvery tips on its wings.

The turkey vulture is the vulture most often referred to as a buzzard. It has a wingspan of about six feet, or over 1.8 meters, although it doesn’t weigh more than about five pounds at most, or 2.4 kg. It’s kind of a picky eater, surprisingly, and doesn’t like really rotten meat. It often hangs out with black vultures, but black vultures are more aggressive even though they’re a little smaller, and the turkey vulture will wait until the black vultures are done eating before it moves in to finish off what’s left.

Black vultures and turkey vultures aren’t very closely related and don’t really look very similar if you see them up close. The turkey vulture has a red head that looks a lot like a male turkey’s, which is where it gets its name. The black vulture has a gray head.

Unlike the turkey vulture, which almost exclusively eats carrion and rotting fruit and sometimes vegetables, the black vulture will also eat eggs and sometimes kills small animals, especially baby animals. It hunts in groups and can even kill newborn calves.

If you want to learn more about the turkey vulture, the Critter Cast Podcast has a really good episode all about it. I’ll put a link in the show notes in case you don’t already listen to Critter Cast.

The other new world vultures are mostly restricted to South America, except for the California condor. We’ll talk about condors in a minute. The king vulture is most common in South America although it also lives in parts of southern Mexico and in Central America. Unlike most vultures, which are mostly black, its feathers are mostly white with some gray and black markings. The skin of its bald head is brightly colored, with different individuals having different coloration—red, orange, yellow, purple, even blue, with an orange crest on its bill in adult birds. It also has a white eye with a red rim, and short bristles on the head. The ancient Maya people considered the king vulture a messenger of the gods, which is pretty neat.

The king vulture is big even for a vulture, with a wingspan of up to about 7 feet, or 2 meters, which makes sense since it’s most closely related to the Andean condor. It has a stronger bill than most vultures, which helps it tear open an animal carcass that other vulture species might not be able to access. Often, other vulture species will wait until a king vulture has opened a carcass and eaten its fill before they move in and eat too. It especially likes the skin and tougher meat of a carcass, and its tongue is raspy to help it pull meat off bones.

The king vulture’s ancestors lived farther north, into parts of North America, but went extinct around 2 ½ million years ago. We don’t really know all that much about the ancestors of the New World vultures, though, because they’re not very common in the fossil record. But the New World vultures are related to the terratorns, huge birds that are extinct now. We’ve discussed terratorns once before way back in episode 17, about the Thunderbird, but let’s discuss them again because they were incredible birds.

We have a decent number of terratorn remains from the La Brea Tar Pits and a few other places. The terratorns were bigger even than condors. A number of species lived throughout the Americas, with even the smaller species having an estimated wingspan of around 12 feet, or 3.8 meters. The largest species known, Argentavis magnificens, lived in South America around six million years ago. It’s estimated to have a wingspan of at least 16 feet, or 6.5 meters, and possibly as much as 26 feet, or 8 meters. That’s the size of a small aircraft.

Researchers think Argentavis was an efficient glider, hardly needing to flap its wings. But it wasn’t very maneuverable, so researchers also think it was probably a scavenger like modern vultures. Smaller terratorns may have been active hunters, more like eagles than vultures. Argentavis had strong legs and probably took off by running into the wind with its massive wings spread, sort of like an airplane taking off, so it didn’t have to flap its wings at all.

That brings us to Grady’s question about why and how buzzards soar for so long. Argentavis would have spent most of its time soaring, hardly ever needing to flap its wings. Its wings weren’t even very strong, and it might not even have been able to flap them when they were extended. The turkey vulture, or buzzard, is especially good at soaring for long periods of time, sometimes for hours, without needing to flap its wings.

If you’ve noticed, soaring birds like vultures, eagles, and hawks tend to fly in circles. There’s a reason for this. When the wind blows over a hill or mountain, it creates an updraft, a breeze that blows directly upward. Similarly, air rises from land that’s been warmed by the sun, causing columns of warm air called thermals. A soaring bird stays in these updrafts and thermals by flying in circles. Vultures also have wingtips where the feathers are spread out, so that each flight feather is separated from the next by a small space. Each of these feathers acts like a tiny wing of its own, which helps keep the vulture gliding forward and not downward. All this wind over the wingtip feathers causes a lot of pressure, though, and vultures have a special bone at the wingtip that helps strengthen and support the flight feathers. Soaring instead of flapping conserves a lot of energy, which is why vultures will soar for as long as they can, looking for food.

Most New World vultures have a good sense of smell, which is unusual for birds. The turkey vulture finds a lot of its food by smell. The black vulture doesn’t have nearly as good a sense of smell, though, and as a result it often follows turkey vultures to find carcasses, then bullies the turkey vultures out of the way to eat first. That’s not very nice, birds. In addition, the turkey vulture has keen eyesight, which helps it find dead animals that might not have started to smell yet.

So let’s talk about those condors now. There are two species of condor alive today, the California and the Andean. We covered the California condor in episode 44, extinct and back from the brink. The California condor actually went extinct in the wild in 1987, with only 22 birds alive in captivity, but an ongoing captive breeding program saved it from extinction and captive-bred birds started to be released into the wild in 1991. But there are still fewer than 500 individuals alive today, so it’s still in danger of extinction. The California condor only lives in a few small areas of western North America today, but around 40,000 years ago it lived throughout North America. Part of the reason it’s still so rare is that it reproduces very slowly. A pair doesn’t nest every year, and even when they do, the female only lays one egg. A young condor depends on its parents for a full year, both for food and to learn how to fly. It can take a young condor months to learn how to fly properly, and researchers sometimes observe awkward crash landings that are probably pretty funny, although maybe not so funny to the condor.

The California condor’s wingspan can be up to almost ten feet, or 3 meters. This is huge, but the Andean condor is even bigger. Its wingspan is nearly eleven feet, or 3.3 meters. The Andean condor lives in and near the Andes Mountains along the western coast of South America. It’s mostly black with silvery patches on the wings and a white ruff around the neck, and its head is gray in color but can flush reddish to communicate with other condors. The male also has a comb on the top of its head.

The Andean condor’s feet are adapted for walking, not fighting. Its feet aren’t very strong and its talons aren’t very sharp. It does sometimes kill small animals like rabbits, but its feet are so weak that it can’t use them to attack. Instead, it stabs the animal to death with its beak.

Like Argentavis, the Andean condor’s wings are built for soaring, not flapping. It can soar for hours without needing to flap its wings once, sometimes traveling hundreds of miles in a day to find food.

It’s a social bird that mates for life, and one of its courtship rituals is a hopping, flapping dance. Keep in mind that this is a bird with wings over five feet long. That would be a pretty impressive dance. The Andean condor nests high in the Andes Mountains on cliffs that predators can’t reach and lays one or two eggs.

Let’s go back to the king vulture now to finish up, because there’s a mystery associated with the king vulture. In the 1770s, a man named William Bartram traveled through Florida and took notes about the animals and plants he saw. He published a book of his travels in 1791 and in it, he included information about a bird he called a painted vulture. He said it was fairly common in Florida and that he’d even shot one himself. The description he gave sounds like a king vulture except that Bartram described its tail as white with a black tip, not entirely black.

But remember, the king vulture primarily lives in South America. It is known in the very southern parts of North America in Mexico, but not Florida. What’s going on?

Some people think Bartram included the painted vulture as a hoax. Some people think he got it mixed up with a different bird, the Northern caracara, a bird of prey which only looks slightly like a king vulture. Some people think there may have been a small population of king vultures in Florida at the time that later went extinct, possibly a subspecies of king vulture with a mostly white tail instead of all black.

Bartram wasn’t the only person who reported seeing the painted vulture. In 1734 an English naturalist and artist, Eleazar Albin, painted a vulture that looked almost identical to the one Bartram described 30-odd years later, tail and all. It’s not completely clear where Albin saw his bird, but as far as researchers can determine Bartram wasn’t aware of the painting. So it’s possible that a subspecies of king vulture once lived in Florida but went extinct soon after Bartram saw it. If he and Albin hadn’t documented it, no one alive today would have any idea the painted vulture ever existed.

You can find Strange Animals Podcast online at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 044: Extinct and Back from the Brink

Our episode this week is about some causes of extinction, but to keep from getting too depressing we’ll look at a lot of animals that were brought back from the brink of extinction by people who saw a problem in time to put it right. We’ll learn a lot about the passenger pigeon this week especially. Thanks to both Maureen and Emily for their suggestions! I didn’t mean to lean so heavily on North American animals in this episode–it just happened that way. I try to mix it up a little more than this ordinarily.

The passenger pigeon (stuffed):

The tiny black robin. It fights crime!

The Tecopa Pupfish is not happy about being extinct:

The West Virginia Northern Flying Squirrel SO CUTE:

This is what the Golden Lion Tamarin thinks about habitat destruction:

A rare Amur tiger dad hanging out with one of his cubs:

The Organization for Bat Conservation

Episode transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’re going to learn about how animals go extinct, with examples of lots of animals who’ve gone extinct and others that have been saved from extinction by human intervention. Both topics were suggestions by Maureen, who also suggested several of the animals I included. I could have kept adding to this episode until it was 24 hours long, but I had to stop somewhere, and now that I’m recording I realize there are aspects of extinction I didn’t address at all.

Extinction means that a population of life forms have all died. That sounds pretty definitive, but it’s also hard to know exactly when it’s happened for any given species. Sometimes you can look online and find the specific day that the very last animal of a species died. In the case of the passenger pigeon, that was September 1, 1914, when a captive bird called Martha was found dead in her cage. Martha had been kept in the Cincinnati Zoo long after the last wild passenger pigeon was shot around 1901. But we don’t know for sure that she was the very last passenger pigeon alive at that point. Passenger pigeons were spotted in the wild for years after Martha died.

The passenger pigeon looks similar to the mourning dove, which is a common and very pretty dove throughout most of North America, but it’s not all that closely related. The passenger pigeon was a swift and elegant flyer but was awkward on the ground. And while mourning doves have a soft, musical call, the passenger pigeon apparently didn’t sound very musical at all. Its calls were mostly loud, harsh clucks that were described as deafening when one of the massive flocks of birds took off in alarm.

So what caused the passenger pigeon to go extinct? As is often the case, it wasn’t just one thing. We’ll come back to the passenger pigeon later, but for now let’s discuss one rather unusual cause that contributed to its extinction.

The passenger pigeon was famous for its numbers. There may have been as many as five billion birds alive at any given time, in flocks that numbered millions of birds each. I’m not exaggerating, either. A single flock could take an entire day to fully pass overhead and literally darkened the sky, there were so many individual birds. With so many birds, it wasn’t that hard for hawks and other hunting birds to catch as many pigeons as they could eat—but there are only so many hawks, and millions upon millions of pigeons. The passenger pigeon also nested in a relatively small area within its eastern North American range. Its nesting colonies were so huge they were called cities. A female laid one or two eggs, which both parents incubated. Sometimes there were so many pigeons in a tree that limbs would break off. By the end of nesting season, pigeon poop underneath roosts could be as deep as a foot, or 30 cm.

And while millions of adult birds were tending millions of eggs and babies, predators gorged themselves on pigeon. Hawks, eagles, owls, and other birds of prey naturally caught lots of pigeons, but other animals moved in to take advantage of the buffet. Bears, foxes, wolves, mountain lions, and smaller animals like possums and raccoons would all eat as much pigeon as they could catch. But there were so many birds that there literally weren’t enough predators to make a dent in the population before the babies could fly and the flocks left the nesting grounds for another year. I mean, birds sometimes just laid their eggs directly on the ground. They were not very hard to catch.

The problem was that once the passenger pigeon’s numbers fell due to other factors, the predators’ yearly glut of pigeon eating started making a difference. The once enormous flocks grew smaller and smaller. And since the passenger pigeon was adapted to thrive in huge colonies, where individuals worked together to gather food and feed babies communally, once the flocks dropped below a certain number, the birds weren’t able to raise their young effectively.

This is depressing, so let’s cleanse the palate with a bird that was saved from certain extinction not too long ago. There are actually a number of species I could have chosen, but I decided on the black robin because it’s tiny, jet black, and has a name that sounds like an alternate-universe DC comic book character.

When I say robin, my North American listeners think of a big thrush-type bird that always looks like it’s frowning, and my European listeners think of a tiny round ball of floof. The black robin is the round ball of floof type, but it’s not from Europe. It’s found only on a few small islands off the coast of New Zealand—really small islands. In 1980, the entire population of black robins lived on Little Mangere Island, which is 279 acres in size, or 113 hectares. Of course, the entire population of black robins in 1980 was five individuals, only one of which was a female. That bird was called Old Blue, and she basically saved her species. A team of conservationists led by Don Merton established a breeding program and today there are more than 250 of the birds.

The black robin was almost driven extinct mainly by introduced predators like cats, rats, and dogs. That’s a common problem, especially in island habitats. Like the dodo, the black robin had never had to deal with mammals that wanted to eat it. It isn’t entirely flightless but it spends most of its time on the ground, digging through brush and dead leaves for insects, and isn’t a very strong flier.

Habitat loss is another huge cause of extinction, and if I wanted to spend all year on this one topic I could. But I won’t, because that would be really grim and not fun at all. One of the factors contributing to the passenger pigeon’s extinction was habitat loss. It mainly ate acorns and small nuts, insects, and seeds found in forests, and when European settlers decided they wanted to turn huge sections of North American woodland into farms and towns, the passenger pigeon soon didn’t have enough forested areas to sustain its massive population. It would have had a hard time as a result even if all other factors had been in its favor.

Habitat loss doesn’t just mean cutting down trees. It can mean polluting a river, bottom dredging in the ocean, diverting water to farmland, and filling in wetlands. It also isn’t always caused by humans. Natural causes like forest fires and volcanoes can lead to habitat loss and extinctions. And many of the dinosaurs, of course, were killed off by a massive meteor impact and its long-term repercussions on climate.

I could choose any of literally thousands of examples of animals that went extinct due to habitat loss, but here’s just one. I mainly chose it because it has a cute name. The Tecopa pupfish was an awesome little fish that lived in California, specifically in the Mojave desert, which is not a place you’d ordinarily expect to find any fish. There are hot springs in the Mojave, though, and the pupfish lived happily in water that was 110 degrees F, or 43 C, or even a little warmer. That’s the temperature of a comfortably warm bath. It ate algae but it also gobbled up mosquito larvae, and it was only about an inch and a half in length, or 4 cm. It didn’t live in the actual hot springs pools, which were too hot, but in a pair of outflows, basically streams that flowed away from the pool down to the Amargosa River.

The problem is, humans really like hot springs. In the 1950s and 60s, people flocked to the Tecopa Hot Springs to soak in the water. Bathhouses were built, the hot springs pools were enlarged, and in 1965, both outflows from the springs were diverted into a single newly dug channel. After that, the water flowed faster. That meant it remained too hot for the pupfish unless the fish moved downstream, and when it moved downstream to where it was comfortable, it had to compete with another subspecies of pupfish, the Amargosa River pupfish. It also had to compete with introduced species of fish.

By 1966, almost no Tecopa pupfish remained. In 1970 it was put on the endangered species list, but by then it was far too late. By 1972 there were no Tecopa pupfish.

Oh my gosh, that’s so depressing. I need another success story. The West Virginia Northern Flying Squirrel is an adorable and fascinating rodent, a subspecies of the more common northern flying squirrel, but it lives only in the highest elevations of the central Appalachian Mountains. During the ice ages, it was isolated from other flying squirrel populations by glaciers and developed separately. It has a broad, flat tail and loose folds of skin that connect its forelegs to its hind legs along its sides. When it jumps from a branch, it holds its legs out to pull the skin folds taut, which allows it to glide through the air.

But it almost died out completely due to industrial logging. By 1985, only ten individuals were found in four different areas of its range. It was listed as a protected species in 1985, and that together with the conservancy of its mountaintop habitats, allowed it to increase to a small but healthy population today.

The West Virginia Northern Flying Squirrel was lucky because its habitat became protected and started to recover from heavy logging, so the flying squirrels were able to stay put and lead their ordinary squirrelly lives. Other species aren’t as fortunate. The Golden Lion Tamarin, for instance, has been snatched from the jaws of certain death but still faces an uphill battle due to habitat destruction.

The golden lion tamarin is a monkey native to the coastal forests of Brazil. It’s a gorgeous monkey with golden-orange fur that grows long around the face so it looks like a lion’s mane. The golden lion tamarin is only around 10 inches long, or 25 cm, not counting its long tail, and it lives in trees where it runs and leaps and climbs a lot like a big golden squirrel.

The problem, of course, is that the Atlantic Forest of Brazil keeps getting cut down. What used to be nearly unbroken forest that stretched for thousands of miles has now shrunk to only around 8% of its original size, and it’s in little bits and pieces widely separated from each other. By 1969, there were only 150 tamarins left.

Fortunately for everyone, especially the tamarins, an aggressive conservation program was well underway by 1984. Zoos throughout the world started breeding golden tamarins for reintroduction into protected wilderness in Brazil. As it happens, while I was still researching this episode, I got an email from a listener that is just so perfect, I have to share it. Emily wrote,

“I used to volunteer at the zoo and I was in charge of making sure the Golden Lion Tamarin monkeys didn’t escape their habitat. There were no fences around it, since they were trying to simulate natural conditions enough so that they could eventually be released back into the jungle. So my job was to walk around the enclosure and shoot them with a water gun. It was set on “very soft.” Just a gentle aquatic nudge to get back in the tree! They were tiny, luxurious creatures and I hated it when my scheduled changed and I had to stop volunteering.”

I love this so much. Thank you, Emily, for sharing the story with me and agreeing to let me use it on the show. I feel like I should pause for a moment so everyone listening can just imagine how awesome it would be to walk around spritzing beautiful little monkeys with water.

Anyway, the population of golden lion tamarins is now over 3,000. And even better, the Brazilian government has made an effort to develop protected wilderness corridors connecting what used to be separate sections of forest. This will help not just the tamarins but lots of other animals too.

Now I feel great. But we’re not done talking about causes of extinction, and unfortunately we’ve reached the worst part: overhunting by humans.

That was the main cause of extinction for the passenger pigeon. People would just shoot up into the air at the seemingly endless flocks of birds. They didn’t even have to aim. Every shot would bring down a rain of dead and injured birds. Almost no one imagined the passenger pigeon could possibly go extinct—there were just too many of them. Even when the flocks were noticeably smaller and the birds’ range had shifted away from the more populated eastern states, professional hunters and trappers continued to follow the flocks and kill as many birds as possible. The dead pigeons were shipped by train to big cities as cheap meat—so cheap that by 1876 it actually cost more to ship a barrel of pigeons on ice than it cost to buy the pigeons when they arrived. By 1878, only one large nesting site remained—and 50,000 pigeons were killed there every single day. No babies survived from that nesting and the surviving adults were killed when they tried to start new nests in another area.

It was senseless. It makes me so mad. But while the passenger pigeon was a great big lesson on how quickly a species can be driven to extinction from an enormous, thriving population, it happens on a smaller scale all the time.

The Caribbean Monk Seal, sometimes called the wolf seal, grew to about 8 feet in length, or 2.5 meters, and had sleek dark gray fur that sometimes looked greenish due to algae growing on it. They were curious, friendly animals that didn’t fear humans, and you can see where this is going. The first European to see the Caribbean monk seal was Christopher Columbus, whose men killed eight seals. The next European to see the Caribbean monk seal was Ponce de Leon, whose men killed 14 seals. Things didn’t get any better from then on.

Seals provided oil from their fat, much like oil made from whale blubber. It could be used to grease machinery or burn in lamps—remember, this was before petroleum products and electricity. Hunting the seals for oil, meat, and skins wasn’t the only problem, though. Conservation back in the 19th century wasn’t all that great. Scientific expeditions usually just killed as many animals as they could find, because that was how they were studied. In only four days, an 1886 expedition specifically made to study seals killed 42 animals and captured a newly born pup that died a week later.

The Caribbean monk seal held on for decades despite the slaughter, but the last one was spotted in 1952 and that was it. Not only were the seals hunted nearly to extinction, the fish and crabs the seals ate were also overhunted. What seals remained had almost nothing to eat and frequently starved to death.

We need a big success story after that one. Let’s talk about the California condor.

The California condor is an enormous bird with a wingspan ten feet wide, or over 3 meters. It’s a scavenger so it looks superficially like a vulture, with a bald head. Its feathers are black with white patches under the wings, and it has a floof of feathers around its neck that looks precisely like it’s wearing a really fancy opera cape. By 1987, the entire world population of the California condor was 27 birds. And those 27 birds were not going to survive long without help. Poaching and habitat loss had almost wiped them out, along with poisoning from lead bullets—the birds would eat the bullets frequently left in the discarded guts after a hunter field dressed a kill.

So all 27 birds were captured and placed into a breeding program, although only 14 birds were able to breed. By 1991 there were enough condors that individuals started to be released into the wild again. Currently there are almost 450 birds total.

Fortunately, in 2019 California hunters will no longer be allowed to use lead bullets at all, and a lot of hunters have already started using lead-free ammunition. This will allow more condors to be released in areas of California where they used to live but were hunted to extinction over a century ago. Lead poisoning is a big problem for all scavengers, including bald eagles.

Our last success story is the Amur tiger, also called the Siberian tiger. It had a lot of names in the past because its range was so large, from Korea to northeastern China, eastern Mongolia, and parts of Russia. It’s a big tiger, as big as the Bengal tiger in the past although the remaining population of Amur tigers is overall smaller than Bengal tigers today. Its head is broad, with a skull similar to a lion’s. Its coat color and markings vary considerably, and its winter coat grows very long and shaggy.

The Amur tiger was already under pressure from hunting and habitat loss when the Russian Civil War broke out in 1917. Tigers were either killed by accident during the fighting, or killed by soldiers on patrol, almost wiping out what animals remained. And after that, tiger hunting wasn’t prohibited until 1947, at which time only a few dozen tigers were left.

Fortunately, it survived. In 2007 the Russian government even set aside a national park just for the Amur tiger. No human activity is allowed in most of the park and tiger numbers are climbing. In 2015, a logging company agreed to dismantle abandoned logging roads so they couldn’t be used by poachers. Bridges were removed, trenches dug, and some areas were simply bulldozed so that vehicles can’t get through. That’s the same year that camera traps got rare photos of an adult Amur tiger male, a female, and three cubs. Since male tigers are usually solitary, that was pretty awesome.

Genetically the Amur tiger is very similar to the extinct Caspian tiger. There’s a possibility that as the Amur tiger’s population grows, it could be reintroduced to parts of Asia where the Caspian tiger once lived.

That brings me to something I meant to mention in last week’s episode. If you listened to the recent Relic: The Lost Treasure podcast episode where I was a guest, you heard me absolutely mangle an explanation of what a subspecies is. So here’s my attempt to clarify what I was trying to say. A subspecies develops when an animal population becomes isolated from the rest of the population for long enough to start evolving in different ways from the parent population. A subspecies can still produce fertile offspring with the parent species and other subspecies of the same species, and may look almost the same, but on a molecular level it’s different enough that if given enough time, it will continue to develop into a different species.

It’s a complicated topic and I said the word species too many times. But hopefully that gives you an idea. Technically humans are a subspecies of Homo sapiens, by the way. Our official scientific name is Homo sapiens sapiens. The extra sapiens indicates that we’re a subspecies and that we’re extra smart, because sapiens means intelligent. All tigers are subspecies of the species Panthera tigris, and the Bengal tiger is called Panthera tigris tigris, because I guess they’re extra tigery.

Anyway, it’s important to remember that while a subspecies may look almost identical to the parent species, it’s developing in different ways due to different evolutionary pressures in its specific habitat. The dodo’s ancestor was a type of pigeon that decided to stay on the island of Mauritius. It probably continued to look like a pigeon for a long time before its evolutionary changes started to show. It’s easy to think that a subspecies going extinct isn’t as important as a full species going extinct, but that’s not the case.

Thinking about extinction can make us feel angry and helpless. But there are lots of things you can do to help, simple things like picking up trash when you’re out hiking, remembering to bring your reusable bags into the grocery store, and using a refillable water bottle instead of buying a new plastic bottle of water. If you have some extra money, there are lots of good conservation organizations that can use a donation. One I try to donate to every year is the Organization for Bat Conservation. I’ll put a link to it in the show notes if you’re interested. If you don’t have extra money but can donate your time to a local organization, that’s just as good. Although you probably won’t be lucky enough to get to spritz monkeys gently with water.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on iTunes or whatever platform you listen on. We also have a Patreon if you’d like to support us that way.

Thanks for listening!

Episode 017: Thunderbird

We’re talking about Thunderbird this week and the huge North American birds that may have inspired Thunderbird’s physical description. Thanks to Desmon of the Not Historians podcast for this week’s topic suggestion!

Further listening:

While I was in the middle of researching this episode, Thinking Sideways did a whole episode on Washington’s Eagle.

Further reading:

“The Great Quake and the Great Drowning”

“The Myth of 19th Century Pterodactyls”

Depiction of Thunderbird on a Pacific Northwest totem pole:

A wandering albatross hanging out with a lot of lesser birds. Biggest wingspan in the world right here, folks!

A California condor. #16, in fact.

An adult bald eagle with a juvenile.

Washington’s eagle as painted by James Audubon

Model of a teratorn. We don’t actually know what colors they were.

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week’s episode about Thunderbirds was suggested by Desmon of the Not Historians Podcast, a fun, fascinating podcast about history. If you haven’t given it a listen yet, I recommend it.

Despite my interest in birds, before I started research for this episode, I didn’t know much about the Thunderbird. I knew it was an element in First Nations lore but I didn’t know which tribes or regions, just assumed it was out west somewhere. Since I live in East Tennessee, “out west” to me is a vague wave of the hand and a mental image of wide-open plains and buffalo and maybe John Wayne. But it turns out that the Thunderbird is an important element in Northeastern and Pacific Northwest tribal lore, as well as being well known among the Great Plains societies and beyond. Thunderbird, in fact, is one of the most widespread figures in Native American lore.

I’m always cautious when mystery animal research points me to religious lore. Many cryptozoologists like to mine myths, legends, folktales, and religious stories of all kinds to find corroboration for the existence of their personal pet cryptid, but if you aren’t extremely well versed in the culture, it’s easy to misinterpret elements of a story. Worse, some cryptozoologists do this on purpose, running roughshod over sacred beliefs and yanking out one mention of, for instance, a giant human and then shouting about how this tribe clearly knows all about Bigfoot. Not to pick on the Bigfoot hunters, but guys, you need to calm down.

Thunderbird is associated with storms but it’s not accurate to say he’s a storm god. He’s more of a representation of the uncontrollable power of nature. In many Plains societies, Thunderbird is associated with trickster figures and a deep belief in the dual aspect of nature—that things in nature often hold their own opposites, that everything found in nature is reflected and represented in the human world.

Thunderbird is not necessarily a single being, either. Many tribes have stories about four different varieties of Thunderbird represented by different colors. Sometimes the different colored Thunderbirds correspond to the cardinal directions, sometimes not. And while Thunderbird is generally supposed to be an enormous eagle-like bird, the difference between bird and human is frequently blurred in the stories. This blurring of human and animal traits in stories is true across all cultures, incidentally, and if you doubt me, think about “what big eyes you have, granny.” Animal beings in traditional stories of all types are allegories, not real animals or real people.

The Thunderbird is also an allegory, a spiritual being, and it’s a disservice to the rich and sophisticated First Nations cultures to strip those trappings away and try to find nothing but a bird underneath. That’s not to say the physical form of Thunderbird wasn’t inspired by eagles or other birds. Just don’t dismiss a culture’s spiritual world to root out so-called proof of a natural explanation.

But. That doesn’t mean there aren’t any gigantic honkin birds in North America and throughout the world.

Going by wingspan, the biggest known living bird is the wandering albatross. Its wingspan can exceed 12 feet, with unconfirmed rumors of individuals with wingspans topping 17 feet. That is an enormous wingspan, seriously. I’d love to see one. The wandering albatross looks like an enormous seagull, white with black wings and a pink bill and feet. Males have more white on the wings—sometimes only the wingtips are black—and a peach-colored spot behind the head. Like many seabirds, albatrosses have a salt gland in their nostrils that helps filter excess salt from the body.

The wandering albatross spends most of its life on the wing far out at sea. It can soar for hours without needing to flap its wings. It eats fish and other animals it can catch at the surface of the ocean or in shallow dives, and sometimes will eat so much it can’t fly and has to sit in the water while it digests. I feel that way every time I go to a buffet.

But since the wandering albatross, as well as its somewhat smaller relatives, lives around the southern sea at the south pole, I think we can safely say that it wasn’t an inspiration for Thunderbird. Besides, it’s basically a giant seagull. Not exactly Thunderbird material.

The California condor’s wingspan is ten feet, and many people point at it as a possible Thunderbird model. But the condor is a type of vulture, which means it has a bald head and mostly eats carrion. Vultures evolved bald heads to reduce bacterial growth in their feathers, since yeah, they sometimes stick their heads in dead animal carcasses to get at those yummy soft parts. No matter how magnificent a wingspan the condor has, it doesn’t fit the stories of Thunderbird battling creatures like Horned Snake, since vultures aren’t raptors and their bills and claws are relatively weak. The same holds true for the Andean condor, with a wingspan of eleven feet, not to mention that bird lives in South America.

The trumpeter swan has a wingspan of over ten feet and lives in North America, but while swans can be aggressive, they eat aquatic plants and act like gigantic ducks, not exactly fierce Thunderbird material. The American white pelican likewise has a ten-foot wingspan but, well, it’s a pelican.

So what about North American eagles? We only have two known species, the bald eagle and the golden eagle. Both have wingspans that can reach more than eight feet and, tellingly, both are common throughout the Pacific Northwest and throughout most of North America. It’s entirely possible that admiration of these large eagles gave form to descriptions of the Thunderbird.

But while an eagle with a nine foot wingspan is impressive, let’s not fool ourselves. We all want to know about GIANT HECKIN HUGE BIRDS. Like, twice that size! This is what cryptozoologists so often dig around for in Native Thunderbird legends, hints that there was once and maybe still is a bird so enormous that it inspired terror and awe in people who saw it, to the degree that they immortalized it in cultures throughout North America as the Thunderbird.

In cultures without written language, stories impart knowledge of everything—history as well as religion, warnings of real-life dangers as well as rituals to ward off the danger—and many stories serve dual purposes. Among the Pacific Northwest peoples, certain stories about Thunderbird battling Whale commemorate a cataclysmic event now known to science, a violent earthquake on Jan. 16, 1700. It was probably a magnitude 9 quake that dropped the coast as much as six and a half feet and resulted in tsunami waves drowning villages from northern California to southern Vancouver Island. In the 1980s a team of researchers studying the geology of the area looked closely at stories of the Makah people in Washington state. Soon they learned that all the indigenous peoples along the coast had stories about the earthquake.

The difference between that study and cryptozoologists looking for Bigfoot or a real-life Thunderbird is one of training and intent. The 1980s team consisted of anthropologists, geologists, and indigenous scholars. And they weren’t cherrypicking information that matched what they had already decided was the truth. What they discovered among the Pacific Northwest peoples guided their research and helped them learn more about the infrequent but violent earthquakes in the area. They even uncovered stories that may be about older quakes and tsunamis.

The problem is that stories about events that happened a long time ago tend to fall out of circulation eventually, especially if the events are no longer relevant. The earthquake stories were hard to gather in the 1980s because the event that inspired them happened almost 300 years before. How much can you remember about the year 1700 without looking it up online? And in the meantime, other cataclysms, notably invading Europeans bringing diseases like smallpox, destroyed much of the native culture.

In other words, even if you’re a trained anthropologist with a deep understanding of the cultures you’re studying, teasing historical information about giant birds from Native American stories is next to impossible. We know truly gigantic birds used to exist in North America because we’ve found their remains, but we can never know for certain if any of those birds inspired Thunderbird legends in any way or if the birds were ever even seen by humans.

Some of the largest flying birds that ever lived are known as pseudotooth birds because their beaks had toothlike spines. They were big, slender birds that probably looked a lot like albatrosses although at the moment they’re classified as more closely related to storks and pelicans. While we don’t have any complete skeletons, researchers estimate the birds’ wingspans may have been as much as 20 feet. One species, Pelagornis sandersi, may have had a wingspan as wide as 24 feet. I just went outside and measured the road in front of my house, and it’s only about 18 and a half feet wide, just to put that into perspective. It’s probable the pseudotooth birds weren’t actually able to flap their wings, just soar.

Like albatrosses, the pseudotooth birds probably covered vast distances in flight. Their remains have been found in North and South America, New Zealand, parts of Africa and Europe, Japan, even the Antarctic. They ate whatever they could scoop up from the water with their long bills. The toothlike projections on their bills weren’t very strong and just helped the bird keep hold of wriggly fish, but they certainly look impressive.

But from what we know from the fossil record, the pseudotooths all died out by the early Pleistocene, some two million years ago. Homo habilis may have seen them flying off the coast of Africa, and if so I bet our distant ancestors thought something like, “Wow, that’s a huge bird!”

The group of North American birds that a lot of cryptozoologists want to call the Thunderbird is the teratorns. Some of them were as big as pseudotooth birds with 20-foot wingspans, but they looked much different. They’re related to the New World vultures, but their bills are more eagle-like, indicating that teratorns were active hunters that could probably swallow prey as large as rabbits whole. Formerly some researchers thought the biggest teratorns couldn’t fly, but new discoveries of fossils with contour feather attachment marks indicate they could. But since teratorns had long, strong legs as well, they might have sometimes stalked their prey on foot the way golden eagles occasionally do.

We have a lot of teratorn remains from the La Brea tar pits. Teratornis merriami had a wingspan of about 12 feet and lived until only about 10,000 years ago. The biggest teratorn is Argentavis magnificens, which lived in South America and probably went extinct around 6 million years ago. It had a wingspan of at least 20 feet, possibly more than 25 feet, but we don’t have very many fossils of this bird. Only one humerus has been discovered—that’s the upper arm bone, and it’s the length of an entire human arm.

It would be truly magnificent if a teratorn descendent still existed. Some people think it did, at least until a few hundred years ago. We might even have a depiction of one by the most famous bird artist in the world, James Audubon.

In February 1814, Audubon was traveling on a boat on the upper Mississippi River when he spotted a big eagle he didn’t recognize. A Canadian fur dealer who was with him said it was a rare eagle that he’d only ever seen around the Great Lakes before, called the great eagle. Audubon was no slouch as a birdwatcher and was familiar with bald eagles and golden eagles. He was convinced this great eagle was something else.

Audubon made four more sightings over the next few years, including at close range in Kentucky where he was able to watch a pair with a nest and two babies. Two years after that, he spotted an adult eagle at a farm near Henderson, Kentucky. Some pigs had just been slaughtered and the eagle was probably coming by to look for scraps. Audubon shot the bird and took it to a friend who lived nearby, an experienced hunter, and both men examined the body carefully.

According to the notes Audubon made at the time, the bird was a male with a wingspan of 10.2 feet. Since female eagles are generally larger than males, that means this 10-foot wingspan was likely on the smaller side of average for the species. It was dark brown on its upper body, a lighter cinnamon brown underneath, with a dark bill and yellow legs.

Audubon named the bird Washington’s eagle after George Washington and used the specimen as a model for a lifesized painting. Audubon was meticulous about details and size, using a double-grid method to make sure his bird paintings were precisely exact. This was long before photography, remember.

So we have a detailed painting and first-hand notes from James Audobon himself about an eagle that…doesn’t appear to exist.

Now, this isn’t the only bird Audubon painted that went extinct afterwards. He painted the ivory-billed woodpecker, subject of our episode nine, and the passenger pigeon, along with less well known birds like Bachman’s warbler and the Carolina parakeet. Yeah, North America used to have its very own budgie that was cute as heck, but it’s long gone now.

To add to the confusion, though, Audubon also made some mistakes. Selby’s flycatcher? Nope, that was just a female hooded warbler. Many people think Washington’s eagle was just an immature bald eagle, which it resembles.

I don’t actually agree. I’m just going to say that right out. Let me explain why.

There are reports of bald eagles with wingspans of nine feet, although I couldn’t find any verified measurements that long. A bald eagle will actually have a slightly wider wingspan as a juvenile than as an adult because of the way its feathers are arranged, but that difference is a matter of a few inches, not feet. In addition, the largest bald eagles are found in Alaska; individuals in the southeastern United States are usually much smaller. And female bald eagles are typically as much as 25% larger than males.

But here we have a male eagle shot in Kentucky with a measured wingspan of 10.2 feet. Juvenile bald eagles do travel widely, but even if that happened to be an outrageously large individual who’d flown down from Alaska, consider that Audubon had seen the same type of eagle nesting a few years before near the same area. He’d watched a pair feeding two chicks. Immature bald eagles don’t nest or lay eggs. There are other differences too, notably the color and size of the nostril area and the type of scaling on the legs.

Golden eagles also resemble juvenile bald eagles to some degree, but they don’t nest in Kentucky. Their winter range just barely touches Kentucky, in fact. They nest in Canada and in the western half of the United States. And the largest golden eagle ever measured was a captive-bred female with a 9.3 foot wingspan, and like bald eagles, golden eagle females tend to be considerably larger than males. A male with a wingspan of over ten feet is probably not too likely; but even if an aberrantly large male golden eagle decided to vacation a little farther south than usual, it’s clear from many details in Audubon’s painting and in his notes that the bird he shot can’t be a golden eagle.

Audubon kept diaries of his birding trips so we know he was familiar with juvenile bald eagles—he even painted one. We also know he differentiated between juvenile bald eagles and Washington’s eagle, which he wrote was about a quarter larger than the juvenile bald eagle.

And Audubon wasn’t the only person to have reported the eagle. From other reports we know it hunted differently from bald eagles, including no reports of it stealing fish from ospreys the way bald eagles frequently do (the jerks). Washington’s eagle reportedly preferred to nest in rocky cliffs near water, not in trees like bald eagles.

So I don’t think Audubon was mistaken or lying. I think he really did paint a type of eagle that was already rare in the early 19th century and which went extinct soon after. Unfortunately, Audubon’s mounted specimen has been lost, but it’s always possible there are other specimens floating around in personal collections or museum storage rooms, possibly mislabeled as juvenile bald eagles.

There’s not a very good chance that Washington’s eagle survived into the present day just because its immense size would make it easy to spot. Then again, size is really hard to estimate without something of known size to compare it to. Is it a gigantic eagle that’s really high up or an ordinary eagle at a closer distance? Combine that with Washington’s eagle looking so much like a juvenile bald eagle and there could be a remote population hiding in plain sight.

There are, of course, lots of reports of giant birds in North America. Most take place along roads or in back yards, where people catch glimpses of eagles of unbelievable proportions—literally unbelievable, in fact, 15 or 20 or even 25-foot wingspans and birds that pick up deer and fly off with them. Most of these are probably misidentifications of known birds of prey with size exaggerated due to alarm, poor visibility, or just an inability to estimate size correctly. Some may be hoaxes. But there’s always the possibility that in this case we might really have a very rare, very large eagle still living in remote areas of Canada or Alaska, and occasionally one flies into more populated areas.

Let’s hope someone finds some remains, either taxidermied specimens or a collection of bones and feathers in some protected cave, so they can be tested and we can find out if there’s a real live teratorn still flying around—or at least learn if there are three species of eagle in North America instead of just two.

I don’t know if Washington’s eagle has anything to do with the Thunderbird. In my mind they feel like two completely separate entities: a flesh and blood eagle circling high above a lake in search of prey, and a terrifying being wrapped in storm clouds soaring somewhere between reality and the spirit world. Some birds are bigger than others, and some birds have to be taken on faith.

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