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Episode 278: Gender Diverse Animals

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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 263: Pair Bonds

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Thanks to Ella and Jack for this week’s topic suggestion, animals that mate for life or develop pair bonds! Happy Valentine’s Day!

Further reading:

Wisdom the albatross, now 70, hatches yet another chick

The prairie vole mates for life:

Swans mate for life:

The black vulture also mates for life:

The Laysan albatross:

Wisdom the Laysan albatross with her 2021 chick (pic from the link listed above). I hope I look that good at 70:

Dik-diks!

The dik-dik nose is somewhat prehensile:

The pileated gibbon (and other gibbons) forms pair bonds:

Show transcript:

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

Last February Ella and her son Jack suggested a Valentine’s Day topic. I already had the February episodes finished last year, but this year Valentine’s Day falls on a Monday and that just seems too perfect to pass up. So thanks to Ella and Jack, we’re going to learn about some animals that are monogamous.

Valentine’s Day falls on February 14th and in many European cultures is a day celebrating love and romance. It also falls at the very beginning of spring in the northern hemisphere, when many animals start finding mates.

Different species of animal have different relationships. Some animals are social, some are solitary. Every species is different because every species has slightly different requirements for reproducing due to different habitats, foods, how much care the babies need, and so forth.

There are different types of monogamy among animals and it can get complicated, just as it’s often complicated in people, so I’m going to simplify it for this episode into two categories: animals that mate for life and animals that form pair bonds. Animals that mate for life, meaning the male and female seek each other out every mating season to have babies together, don’t necessarily spend all their time together outside of mating season. Animals in pair bonds spend a lot of their time together, but they don’t always exclusively mate with each other. But some animals do both.

For instance, the prairie vole. This is a little rodent that lives in dry grasslands in central North America, in parts of the United States and Canada. It’s about the size of a mouse with a short tail although it’s more chonky than a mouse, like a small dark brown hamster. It spends most of its time either in a shallow burrow it digs among grass roots or out finding the plant material and insects it eats by traveling through aboveground tunnels it makes through densely packed plant stems. It lives in colonies and is a social animal most of the time, and the male in particular is devoted to his mate. He’s so devoted that once he’s found a mate, he will even drive away other females who approach him.

The only time the prairie vole isn’t social is during mating season, which is usually twice a year, in fall and in spring. At that time, mated pairs leave the colony and find a small territory to have their babies. The pair spends almost all their time together, grooming each other, finding and sharing food, and building a nest for the babies. When the babies are born, both parents help care for them.

The male prairie vole mates for life. Most of the time “mating for life” means that if one of a pair dies, the other will then find a new mate. But for the male prairie vole, if his mate dies, he stays single for the rest of his life. He also shows behaviors that are similar to grief in humans. The female prairie vole is a little more practical and although she also grieves if her mate dies, she’ll eventually find another mate. Researchers who study prairie voles have discovered that the hormones found in mated pairs are the same as those in humans who are in love.

That’s so sweet, and I wish I didn’t have to talk about the voles dying. I think the opposite of love isn’t hate; the opposite of love is grief. It’s okay to be sad even for a long time when someone you love dies or moves far away, or if your own pair bond doesn’t work out. It’s also okay to find happy moments even when you’re grieving. Life is complicated. Also, just going to point out, devoted as they are to each other, sometimes a prairie vole will mate with someone besides their own mate.

One bird that’s famous for being monogamous is the swan. It mates for life and also forms pair bonds. These pair bonds form while the swans are still young, and the young couples basically just hang out together long before they’re old enough to have babies. It’s no wonder pictures of swans appear on so many wedding invitations and Valentine’s day cards. It helps that they’re beautiful birds too. The black vulture also mates for life but no one puts vultures on a wedding invitation. Also, swans sometimes split up and find new mates. Things don’t always work out with a pair bond, even for swans.

Another large, beautiful bird that mates for life is the albatross, but it doesn’t form a pair bond. Most of the time the albatross is solitary, traveling thousands of miles a year as it soars above the open ocean, looking for squid, small fish, and other food near the surface of the water. But once a year in some species, and once every two years in other species, albatrosses return to their nesting grounds and seek out their mate.

Albatrosses live a very long time so are really picky about who they choose as a mate. Once a pair forms, they develop a complicated, elegant dance to perform together. Each couple’s dance is unique, which helps them find each other in a crowded nesting colony when they haven’t seen each other in a couple of years.

The oldest wild bird in the world that we know of is a Laysan albatross named Wisdom. She was tagged by scientists in 1956 when she was at least five years old already, and as of 2021 she was still healthy and producing healthy chicks with her mate. Her leg tag has had to be replaced six times because she’s outlasting the material used to make the tags.

The Laysan albatross is a smaller species of albatross, with a wingspan of not quite 7 feet, or over two meters. Its body is mostly white, although its back is gray, with black and gray wings and a dark smudge across the eyes that looks very dramatic. It spends most of the time in the northern Pacific between the west coast of North America and the east coast of Asia, but it only nests on 16 tiny islands. Most of these are part of the Hawaiian islands with a few near Japan, but recently new breeding colonies have been spotted on islands off the coast of Mexico.

Wisdom the albatross is estimated to be at least 70 years old as of 2021 and she’s raised 30 to 36 chicks successfully. Because of her age, which is old even for an albatross, she may have outlived her first mate and taken another. She’s been with her current mate since at least 2012.

Albatrosses only lay one egg during nesting season. Both parents help incubate the egg and feed the baby when it hatches. It takes two or three months for the egg to hatch, depending on the species. Once the egg hatches, it’s at least another 5 or 6 months before the chick is old enough to leave the nest and care for itself, and in some species this is as much as 9 months. This means a big time and energy investment for both parents.

Albatrosses don’t reach sexual maturity until they’re at least five years old. Birds younger than this still join the breeding colony and practice their dance moves for when they’re old enough to choose a mate.

Pair bonding and mating for life are common in birds, rare in amphibians, reptiles, and fish, and surprisingly rare in mammals. One mammal that both mates for life and forms a pair bond is a tiny antelope called a dik-dik.

The dik-dik lives in parts of eastern and southern Africa and is barely bigger than a rabbit, which it somewhat resembles in shape. It stands less than 16 inches tall at the shoulder, or 40 cm, although its back and rump are arched and rounded and so are actually higher than the shoulder. Females are usually larger than males, while only males have horns. The horns arch back from the head but because the male has a tuft of long hair on the top of his head, and because the horns are only about 3 inches long at most, or 7.5 cm, they can be hard to see.

The dik-dik has an elongated snout that’s somewhat prehensile. It lives in hot areas without much water, so it gets most of its moisture from the plants it eats. Most of the time hot weather doesn’t bother it, but on exceptionally hot days it can cool down by panting through its long nose. Its nose is lined with blood vessels close to the surface and it has special nose muscles that allow it to pant quickly. Air moving over the blood vessels helps cool the blood.

Because pretty much everything eats the dik-dik, traveling long distances to find a mate is dangerous. Once the dik-dik finds a mate, they stay together for life in a small territory and spend most of their time together. Females give birth to one fawn twice a year, and the fawn no longer needs its parents at about 7 months old. Parents drive away their grown offspring, who leave to find a mate and territory of their own.

Humans, of course, strongly pair bond because we’re such intensely social creatures, and many people choose a partner and stay with them for life. Then again, we don’t always. Surprisingly, our closest living cousins, the great apes, are also very social, but they don’t typically form pair bonds and females may mate with different males.

The gibbon, which is a lesser ape instead of a great ape, does often form long-lasting pair bonds. We’ve talked about various species of gibbon in previous episodes. Gibbons are the apes that sing elaborate duets with their mates, with their children sometimes joining in as a chorus.

Here’s a pair of pileated gibbons singing together. The female is named Molly and was in a rehabilitation center after being injured, but she found a wild mate while she was recovering:

[gibbons singing]

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 202: Terror Birds and Pseudotooth Birds

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Let’s find out about some gigantic birds this week! Thanks to Pranav and Richard for the suggestions!

Further reading:

Exceptionally preserved fossil gives voice to ancient terror bird

Antarctica yields oldest fossils of giant birds with 21-foot wingspans

Look at that beak! Llallawavis scagliai:

Big birdie!

A red-legged seriema and an unfortunate snake:

Another big birdie!

Toothy birdie!

Show transcript:

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

This week we’re going to learn about some gigantic extinct birds! Pranav wants to hear about Phorusrhacidae, also known as the terror bird. Something called a terror bird is definitely going to be interesting. My brother Richard also tweeted me about some huge extinct birds called pelagornithids, so we’ll talk about them too. Both birds were huge and successful, but extremely different from each other.

Phorusrhacidae is the name for a family of flightless birds that lived from about 62 million years ago to a little under 2 million years ago. Flightless birds may make you think of ostriches and penguins and dodos, but remember that Phorusrhacids were called terror birds. They were carnivores and many of them were enormous.

Most terror birds lived in South America, with one species known from southern North America. A few newly discovered bird fossils from Africa and Europe may have been close relations of terror birds, but palaeontologists are still studying them.

Various species of terror bird ranged in size from about 3 feet tall to 10 feet tall, or 1 to 3 meters, and had long, strong legs that made them fast runners. The terror bird also had a long, strong neck, a sharp hooked beak, and sharp talons on its toes. The beak was strong but the jaw muscles were relatively weak. Researchers think that it ambushed prey and chased it down, then either kicked it to death with its sharp talons or held it down with its feet and stabbed it to death with its beak. Smaller species may have grabbed its prey and thrown it back down with enough force to injure, stun, or outright kill the animal. It may have swallowed small prey whole and regurgitated pellets made up of compressed fur and bones, the way many modern carnivorous birds do today.

Although the beak was strong, it was also hollow. This would have made it weigh less, which meant that the bird could move its head more quickly. Some researchers think that it might also have acted as a resonant chamber, and that the bird could clap its beak closed to make a loud noise to communicate with other terror birds. It had excellent hearing and vision, but a poor sense of smell.

Many details of what we know about terror birds come from a single specimen discovered in 2010 in Argentina. The bird lived around 3 million years ago and stood four feet tall, or 1.2 meters. It was described in 2015 and is named Scaglia’s magnificent bird. I am not going to attempt to pronounce its scientific name [Llallawavis scagliai], but I’ll put it in the show notes along with a picture. Almost the entire skeleton is preserved in stunning detail, including details that hardly ever preserve, like the tiny bones that help the eye focus. Studies of the tiny ear bones and other details of the ear indicate that its hearing was most acute at low frequencies, which meant it would have been good at hearing footsteps. It also probably had a deep voice.

The terror bird had wings, but they were small and probably only used for display. The wings did have claws, though, and may have been used to fight other terror birds over mates or territory. Young terror birds of some species might have been able to fly, although adults certainly couldn’t.

The earliest known terror bird, Paleopsilopterus, lived about 60 million years ago in what is now Brazil. It was relatively small, only about three feet high, or 1 meter. It evolved only a few million years after the non-avian dinosaurs went extinct, and its descendants became larger and more fearsome until they were apex predators throughout South America.

Kelenken, for instance, grew up to ten feet tall, or three meters, and had an enormous beak, 18 inches long or almost 46 cm. It lived in what is now Argentina around 15 mya. It’s the tallest terror bird known but it was more slenderly built than others so was probably a faster runner. It was only discovered in 1999.

Brontornis, however, was the one that puts the terror into terror bird. It grew over 9 feet tall, or 2.8 meters, but it was massively built. It probably wasn’t a very fast runner and would have definitely been an ambush predator. Most likely it hid among trees or other tall vegetation, and when an animal came too close, BOOM! THERE’S A TERROR BIRD! RUN! TOO LATE, ARGH!

Titanis lived in parts of North America, with fossils found in Texas and Florida. It probably stood a little over eight feet tall, or 2.5 meters, although we don’t have any complete skeletons so can only estimate its actual size compared to other species of terror bird. You may find information online that says Titanis lived as recently as 10,000 years ago in Florida, and that it used the claws on its wings like hands to help catch prey. Both these things are wrong, unfortunately. The fossil bones found in the Santa Fe River in Florida had washed out of their original location and were mixed in with much more recent bones, and there’s no evidence that any terror bird used its wings like hands. Terror birds were descended from birds that could fly, not descended directly from dinosaurs, so its wings were still highly modified for flight.

Titanis lived in North America about five million years ago. But how did it get to North America from South America before the Isthmus of Panama formed around three million years ago? Before then, a big stretch of ocean separated the two continents. Researchers think it island-hopped, as the tops of mountains and hills in what is now Central America first emerged from the ocean as sea levels dropped, forming islands. Volcanoes also formed islands in the area. Titanis may have traveled to these islands by swimming or rafting during storms.

Terror birds went extinct after the Isthmus of Panama opened up when sea levels lowered. This connected North and South America, which allowed animals from North America to cross into South America and vice versa. The Andes Mountains also formed about this time and changed the climate of much of South America. Forests became open savanna where terror birds wouldn’t have been able to hide to ambush prey. Climate change combined with increased competition from saber-toothed cats and other North American predators probably led to the terror birds’ extinction.

There are no descendants of terror birds living today, but its closest living relations are probably the seriema birds, the red-legged and the black-legged seriema. Both live in South America and both are carnivorous birds that eat small animals like rodents, lizards, snakes, and even other birds. When it catches an animal, it beats it against the ground until it dies. It will also sometimes eat fruit and eggs.

The red-legged seriema stands a little over three feet tall, or a meter, with long legs, long neck, and long tail. It’s mostly brown and gray and it has a fan-shaped crest low down on its forehead, just above the bill. The gray-legged seriema looks very similar but is mostly gray. The seriema also has a sickle claw on each foot that it uses to cut pieces off its dead prey so it can swallow them more easily.

The seriema can fly, but it prefers to walk or run. It can run up to 15 mph, or 25 km/h. It builds its nest in low bushes so it can just hop up onto the nest instead of having to fly. It’s also aggressive and will attack animals much larger than it is, driving them away from its nest or chicks. Farmers sometimes catch young seriemas and tame them, then allow them to patrol the farmyard to catch rats and snakes and drive away larger predators.

Next, let’s learn about a different giant extinct bird, Richard’s suggestion. Unlike the terror bird, pelagornithids could fly. They’re sometimes called pseudotooth birds because they had teeth, but they weren’t real teeth. They were pointy projections of the jaw bones that grew along the edges of its beak and were covered with keratin. Pelagornithids evolved around the same time as the terror bird, around 62 million years ago, and didn’t die out until about the same time as the terror bird, around 2.5 million years ago.

And like the terror bird, pelagornithids were huge, but in a different way than terror birds. They were sea birds that may have superficially resembled modern albatrosses, but they were much larger. The largest living albatross has a wingspan of about 11 1/2 feet, or 3.5 meters, but the largest known pelagornithid had a wingspan estimated at up to 21 feet, or almost 6.5 meters. Its wings were narrow and pointed like albatross wings are.

Researchers think that the pelagornithid probably mostly ate soft-bodied animals like squid and other cephalopods, because its teeth were not very strong. It probably scooped its prey up from the water while flying, like many modern seabirds do, although it could probably also sit on the water and dip its long, strong beak down to catch anything that swam too close. Its bones were too delicate for diving. It may have had a throat sac like a pelican too. It was probably white or gray in color and its wings and tail were probably black, which is the most common coloration for sea birds of any kind.

It had short legs but enormously long wings, so long that it probably couldn’t flap them. Its strongest muscles were the ones that held the wings out straight. It was definitely a bird, of course, but it was proportioned more like a flying reptile, Pteranodon, even though they weren’t related. You know what that means, of course. Convergent evolution! Researchers think the pelagornithid spent almost all its time soaring on ocean breezes, scooping up cephalopods and fish to swallow whole, and that Pteranodon probably did the same. These days, modern albatrosses fill that particular ecological niche, and the albatross has many similarities to the pelagornithid too.

Pelagornithids of various species were found throughout the world, from the Arctic and Antarctic to the tropics. It was extremely successful and unlike the terror bird, which was restricted to land, it could travel as far as it liked as long as it had a breeze to keep it aloft. It evolved soon after the non-avian dinosaurs went extinct and didn’t die out until the beginning of the Pleistocene. What happened then? Why aren’t these enormous birds still flying around?

The Pleistocene, of course, was the ice age, or more properly the ice ages. Its onset resulted from a lot of factors, including the movement of continents that changed ocean currents radically. Once the changes started, they accelerated quickly. As more water froze and became massive glaciers that weighted down entire continents, sea levels dropped and more land was exposed, including the Isthmus of Panama that connected North and South America. This would have radically changed the air currents that pelagornithids used to travel around the world, from nesting sites to feeding sites and back. It also drove many sea animals to extinction as their environments became too cold or too warm for them to adapt to, or the water where they lived just dried up completely.

The one place where pelagornithids couldn’t go was across continents. They needed constant sea breezes and lots of water where they could catch prey, and steep cliffs near water to nest on. As the ecological changes of the Pleistocene became more pronounced, pelagornithids had more and more trouble surviving, and finally they went extinct. Modern albatrosses, gulls, and cormorants expanded at the same time to fill the ecological niche left open by the pelagornithid.

While there are no living descendants of pelagornithids, researchers tentatively think they’re most closely related to living ducks, geese, and swans. Since most pelagornithid fossils are badly damaged and fragmented, so that we only have one or two bones preserved from any given animal, it’s hard for scientists to make conclusions as to what they were most closely related to. Hopefully more and better fossils will be found soon so we can learn more about these gigantic birds!

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. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us and get twice-monthly bonus episodes for as little as one dollar a month.

Thanks for listening!

Episode 017: Thunderbird

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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.

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!