Episode 363: The Dodo and Friends

Thanks to Wilmer and Carson for suggesting we revisit the dodo!

Further reading:

Dodos and spotted green pigeons are descendants of an island-hopping bird

On the possible vernacular name and origin of the extinct Spotted Green Pigeon Caloenus maculata

Giant, fruit-gulping pigeon eaten into extinction on Pacific islands

A taxidermied dodo:

The Nicobar pigeon, happily still alive [photo by Devin Morris – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=110541928]:

The 1823 illustration of the spotted green pigeon:

Show transcript:

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

This week we’re going to revisit a bird that everyone’s heard of but no one has seen alive, because it’s famously extinct. We talked about the dodo way back in episode 19, so it’s definitely time we talked about it again. Thanks to Wilmer and Carson for suggesting it! We’re also going to learn about some of the close relations of the dodo.

The first report of a dodo was in 1598 by Dutch sailors who stopped by the island of Mauritius in the Indian Ocean. Mauritius is east of Madagascar, which is off the eastern coast of Africa. The last known sighting of a dodo was in 1662, just 64 years later. The dodo went extinct so quickly, and was so little known, that for a couple of centuries afterwards many people assumed it was just a sailor’s story. But there were remains of dodos, and in the 19th century scientists gathered up everything they could find to study the birds. More remains were found on Mauritius.

In the wild, the dodo was a sleek bird that could run quite fast. It may have eaten crabs and other small animals as well as roots, nuts, seeds, and fruit. It was also probably pretty smart. People only thought it was dumb because it didn’t run away from sailors—but it had no predators on Mauritius so never had to worry about anything more dangerous than an occasional egg-stealing crab before.

When humans arrived on Mauritius, they killed and ate dodos and their eggs. What the sailors didn’t eat, the animals they brought with them did, like pigs and rats. It was a stark and clear picture of human-caused extinction, shocking to the Victorian naturalists who studied it.

A lot of the drawings and paintings we have of dodos were made from badly taxidermied birds or from overfed captive birds. At least eleven live dodos were brought to Europe and Asia, some bound for menageries, some intended as pets. The last known captive dodo was sent to Japan in 1647.

The dodo grew over three feet tall, or almost a meter, with brown or gray feathers, a floofy tuft of gray feathers as a tail, big yellow feet, and a weird head. The feathers stopped around the forehead, making it look sort of like it was wearing a hood. Its face was bare and the bill was large, bulbous at the end with a hook, and was black, yellow, and green. The dodo looks, in fact, a lot like what you might expect pigeons to evolve into if pigeons lived on an island with no predators, and that’s exactly what happened.

The dodo’s closest living relation is the Nicobar pigeon, which can grow 16 inches long, or over 40 cm. Like other pigeons, the dodo’s feathers probably had at least some iridescence, but the Nicobar pigeon is extra colorful. Its head is gray with long feathers around its shoulders like a fancy collar, and the rest of its body is metallic blue, green, and bronze with a short white tail. Zoos love to have these pigeons on display because they’re so pretty. It’s a protected animal, but unfortunately it’s still captured for sale on the pet black market or just hunted for food. It only lays one egg a year so it doesn’t reproduce very quickly, and all this combined with habitat loss make it an increasingly threatened bird. Scientists are trying to learn more about it so it can be better protected.

The Nicobar pigeon lives on a number of islands in the South Pacific and it can fly. Sometimes an errant individual is discovered in Australia, often after storms. Imagine going into your back yard one day and seeing a 40-centimeter-long bird whose feathers shine like jewels! The Nicobar pigeon lives in small flocks and eats seeds, fruit, and other plant material.

An even closer relative to the dodo is also the most mysterious. We don’t even know for sure if it’s extinct, although that’s very likely. It’s the spotted green pigeon and we only have one specimen–and we don’t even know where it was collected, just that it was an island somewhere in the South Pacific. There used to be two specimens, but no one knows what happened to the second one.

For a long time researchers weren’t even sure the spotted green pigeon was a distinct species or just a Nicobar pigeon with weird-colored feathers, but in 2014, DNA testing on two of the remaining specimen’s feathers showed it was indeed a separate species. Researchers think the spotted green pigeon, the dodo, and another extinct bird, the Rodrigues solitaire, all descended from an unknown pigeon ancestor that liked to island hop. Sometimes some of those pigeons would decide they liked a particular island and would stay, ultimately evolving into birds more suited to the habitat.

The specimen we have of the spotted green pigeon is 13 inches long, or 32 cm. Its feathers are dark brown with green iridescence and it has long neck feathers like the Nicobar pigeon. It also has little yellowish spots on its wings and a yellow tip to its bill. Researchers think it was probably a fruit-eating bird that lived in treetops.

The only reason we know there were once two specimens of this mystery bird is from a book about birds published in 1783, where the author mentions having seen two specimens. There was also an 1823 book about birds with an illustration of the spotted green pigeon that differs from the known specimen in some details. Researchers think the illustration might have been painted from the now-missing specimen.

There’s more to this mystery, though, because in 2020 an ornithologist studied a 1928 book about Tahiti that mentioned a bird that sounds a lot like the spotted green pigeon. It was even called a pigeon in the book. Since the author of that book had drawn on studies made by her grandfather almost a hundred years before, and since her grandfather had interviewed Tahitians about their history and traditions and they told him about the pigeon, the ornithologist suggested the spotted green pigeon might actually be from Tahiti. Now that scientists have a clue about where to start looking for remains of the bird, we might learn more about it soon.

Also in 2020, a study was published about another pigeon from the Pacific Islands. Fossils of it were found on the island of Tonga, and the scientists determined that the bird probably went extinct soon after humans first arrived on the island 2,850 years ago. The pigeon has been named Tongoenas burleyi. It grew about 20 inches long, or 50 cm, not counting its tail. It could fly and probably spent a lot of its time in trees, eating fruit. There are lots of different trees on the island that produce really big fruit, some of it as big as a tennis ball. Scientists think the pigeon was adapted to swallow these huge fruits whole, digest them, and poop out the seeds. The trees still exist but they’re in decline and scientists think it may be because no birds remain on the island that can spread their seeds effectively.

We don’t have any feathers from the newly described pigeon, but it was probably colorful. We do have a lot of bones, because many charred bones have been discovered in cooking pits excavated by archaeologists.

We don’t know yet how or if Tongoenas is related to the dodo. The Pacific islands are home to at least 90 living species of pigeon, and many of them we don’t know much about. There are undoubtedly many more waiting to be discovered by scientists, whether living or extinct.

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 for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 360: The Emu War

Apologies to patrons for redoing an old Patreon episode, but I have a cold and it’s the holidays.

The noble emu:

A baby emu (picture from this site, which has lots of good info about emus and lots more great pictures):

Show transcript:

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

I had a different episode planned to finish off the year, but I had lots of stuff to do for the holidays so I put it off, and then I came down with a cold. It’s just a cold, at least, and it’s not too serious, but I decided to repurpose a Patreon episode from early 2020 instead of making a new episode, because I don’t feel good. Apologies to my patrons for getting a rerun, but I did give the episode a brush-up and re-recorded it.

Our topic this week is a bird from Australia, the emu, but mostly we’re going to learn about the emu war that happened in 1932.

The emu is a large, flightless bird almost as big as an ostrich, over 6 feet tall, or 2 meters. Like the ostrich, it can run really fast, over 30 miles per hour, or 50 km/hour. It’s only distantly related to the ostrich, though, and in fact it’s much more closely related to the tiny kiwi of New Zealand.

The emu has long legs and a long neck, soft feathers that are gray and brown, and three toes on each foot. It also has small vestigial wings that are only about eight inches long, or 20 cm. The body feathers make the emu look shaggy, but the head and the upper portion of the neck are less heavily feathered so that it sort of looks like it’s wearing a fancy coat with a high collar. It also looks like it has a poofy wedge of a downward-pointing tail, but it actually doesn’t have much of a tail at all. What looks like a tail is mostly part of the body. The emu’s skeleton is built for running, which includes a modified pelvis and leg bones for the attachment of strong leg muscles.

In winter, the female puffs out her feathers and struts around to attract a mate while making drumlike calls. Females sometimes fight each other by kicking, especially if a female approaches a male who already has a mate. The male builds a nest on the ground by placing dry grass, sticks, bark, and other plant materials on a flat, open area where he can see any predators that might approach.

The female lays up to 15 green eggs that are around five inches long, or 13 cm. The male broods the eggs for the next eight weeks and doesn’t eat during that entire time, and only drinks whatever dew he can gather from the plants around the nest without leaving the nest. A male can lose a third of his weight while brooding. Meanwhile, the female often leaves and finds another mate, sometimes laying several clutches of eggs during the nesting season.

When the babies hatch, the father takes care of them for the next six or seven months, at which point they’re fully grown. While he’s in charge, the father won’t let any other emus near the chicks, even their mother. He teaches them to find food and if the babies feel threatened, they’ll run underneath him to hide. Baby emus have gray and white longitudinal stripes and are super cute.

The emu eats plants and insects, and will sometimes travel long distances to find enough food and water. It can go a long time without eating and several days without drinking. It usually only drinks once a day but it will drink a whole lot of water during that one time.

Some populations of emu migrate to the coast after breeding season, where they can find more food and cooler weather. But in 1932 in western Australia, migrating emus didn’t find their usual food supplies. They found a whole lot of wheat fields cultivated by former soldiers, who had been given land after World War I. The Australian government had encouraged the soldiers to clear the land of native vegetation and grow lots of wheat, which they did. Then the emus showed up.

Naturally, without their usual food to eat, the emus sampled the wheat plants. And they found the plants yummy. Also, even though there was a drought that year, there was plenty of water for the wheat, which meant plenty of water for emus. So the emus showed up and showed up and showed up, an estimated 20,000 emus eating as much wheat as they could hold and crashing through fences to get to it.

The farmers sent a group to speak to the Minister of Defence to get help. The Minister of Defence sent a major with a small handful of soldiers to deal with the birds, with the soldiers armed with two lightweight machine guns.

On November 2, 1932, the men encountered their first emus. The birds were too far away to shoot so the men tried to herd them closer, but the emus scattered instead of staying in a group. Two days later, the men encountered approximately a thousand emus and lay in wait until the birds were close enough to shoot at–but the gun jammed and the birds scattered again. At this point the soldiers had killed maybe two dozen birds in all.

That was enough that the emus had figured out the men were a danger. The men reported that each group of birds now had a lookout. The rest of the flock would eat while the lookout kept watch. When the lookout spotted the men, it warned the others and all the emus would scatter.

The men even tried mounting a machine gun on a truck to run the emus down. But the ground was too bumpy to aim while the truck was moving, plus it couldn’t outrun the emus. On one occasion a dead emu got tangled in the steering equipment and the truck crashed into a fence, destroying both the truck and the fence.

On November 8, the men were withdrawn after having only killed around 200 emus, but they’d used a quarter of the ammunition they’d been allotted to do that. One politician suggested sarcastically that the soldiers deserved a medal for their part in the war, and another politician pointed out that the medal should properly go to the emus.

But the emus were still a problem, so after more entreaties from farmers, the same men and guns were sent back to try again. They kept at it for the next month or so and did manage to kill maybe a few thousand birds, but for every bird they killed, they shot ten bullets. Finally they were recalled for good. The government put a bounty on dead emus instead, and the farmers put up larger and stronger fences. It wasn’t until the late 1960s that the bounty was canceled and the emu protected. The current population is large and healthy.

There used to be several smaller subspecies of emu, but they went extinct basically as soon as Europeans showed up. We’re lucky that the mainland emu survived the war and the bounty hunting so that we can appreciate it today.

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 for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 355: Tiny Owls

This week we learn about two tiny owls! Thanks to Elizabeth and Alexandra for their suggestions!

Further reading:

Burrowing Owl

Elf Owl

The burrowing owl is tiny but fierce [photo by Christopher Lindsey, taken from page linked above]:

The elf owl is also tiny but fierce [photo by Matthew Grube, taken from page linked above]:

Show transcript:

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

This week we’re going to learn about two tiny owls. Thanks to Elizabeth and Alexandra for their owl suggestions!

The burrowing owl is native to the Americas, especially the western part of North America, and most of Central and South America. It prefers grasslands and other open areas. It’s a small owl, not much bigger than the average songbird. It’s mostly brown with lighter underparts that are barred with a brown pattern.

You can tell a lot about an owl by the color of its eyes. In general, an owl with dark eyes is most active at night, an owl with orange or red eyes is likely to be most active at dawn and dusk, and an owl with yellow eyes is often active in the day. That’s not a hard and fast rule, but it can help you make a good guess about an owl’s behavior. The burrowing owl has yellow eyes, and it is indeed active in the day. The term for daytime activity is diurnal.

In past episodes I’ve said that owls have long legs that are usually hidden by feathers. In the case of the burrowing owl, its long legs are in plain sight because it spends a lot of the time running around on the ground. It will sometimes chase prey on foot, but other times it will perch on a fence post, tree branch, or some other high place to watch for a small animal to pass by. Then it will swoop down to grab it just like any other owl. It eats mice and other small rodents, lizards, small snakes, frogs, large insects and other invertebrates like scorpions and caterpillars, and birds. It especially likes termites and grasshoppers. Females are more likely to hunt during the daytime, while males are more likely to hunt at night or at dawn and dusk. Sometimes the burrowing owl will eat fruit and seeds too. When the burrowing owl has more food than it can eat, it will store some in underground larders.

The burrowing owl gets its name because it builds a nest in a burrow in the ground, often in burrows dug by other animals like prairie dogs and skunks. Some subspecies of burrowing owl will dig its own burrow, and all subspecies will enlarge an existing burrow until it’s happy with the size. It uses its beak to dig and kicks the dirt out with its feet. Both the male and female will work on the burrow together. Once it’s the right size and shape, the owl will bring in dried grass and other materials to line the burrow. One of its favorite materials is dried animal dung, especially from cattle. The dung releases moisture inside the burrow, making it more comfortable, and attracts insects that the owls eat. Win-win! It will also scatter animal dung around the entrance of its burrow and will sometimes also collect trash like bottle caps and pieces of foil to decorate the entrance.

The female lays her eggs in the burrow and spends most of her time incubating the eggs, only going outside briefly to stretch her legs. The male stands guard at the entrance to the burrow or nearby except when he’s out hunting. He brings food back for the female.

When the eggs hatch, both parents take care of the babies. At first the chicks stay in the burrow, but as they grow older they come out to play outside and start learning how to fly. Since burrowing owls usually nest in small colonies, there’s always an adult watching for danger somewhere nearby.

Most birds abandon their nests after their chicks are grown. The burrowing owl often uses its burrow year-round, although populations that migrate will usually make a new burrow when they return to their summer range. The burrow gives the owls a place to nap during the hottest part of the day, and it’s also a good place to hide if a predator approaches. Rattlesnakes also use burrows for the same purposes, and when a burrowing owl runs from a predator and hides in its burrow, it will mimic the rattling and hissing of an angry rattlesnake. A lot of times that’s enough to make a predator think twice about digging up the burrow.

This is what a burrowing owl sounds like when it’s not imitating an angry rattlesnake:

[burrowing owl call]

The burrowing owl is increasingly threatened by habitat loss and introduced predators likes cats and dogs. Luckily it’s an adaptive bird and is happy to use artificial burrows in protected areas. It’s a useful bird to have around since it eats a lot of insects, prairie dogs, and other animals that are considered pests by humans. Plus it’s an incredibly cute bird. I mean, it’s a tiny owl with long legs! How could you not find that cute?

Small as it is, the burrowing owl isn’t the smallest owl known. The elf owl is even smaller, about the size of a sparrow. It’s only about 5 inches tall, or 13 cm, with a wingspan of only 9 inches, or 22 cm. It lives in parts of the southwestern United States during the summer and parts of Mexico during the winter.

The elf owl is nocturnal like most other owls, and this is where our guideline of owl eye color breaks down, because the elf owl has yellow eyes. Its feathers are mostly gray or grayish-brown with white streaks. When it’s sitting on a twig, it kind of looks like a dead leaf or a broken-off branch.

It mostly eats insects, but it also likes scorpions, spiders, and centipedes. Occasionally it eats small reptiles or mammals. When it catches a scorpion, it removes the stinger before eating the scorpion, but it doesn’t seem to be hurt by actually being stung. It’s a fast, acrobatic flyer and catches insects on the wing, but it also hunts for insects on the ground and has long legs like the burrowing owl.

The elf owl nests in holes made by woodpeckers in trees or cacti, and the male brings the female food while she keeps the eggs warm. After the babies hatch, the male brings them food too and also continues to feed the female for another couple of weeks, until she starts to hunt again. The male will also catch a tiny snake called the western threadsnake, which looks a lot like an earthworm and only grows a foot long at most, or 30 cm, and is usually much smaller than that. It lives underground most of the time and while it has eyes, they don’t work except to sense light and dark. It eats insects, especially termites and ants. When an elf owl catches one of these little snakes, it doesn’t eat it. Instead, it brings the snake back to the nest and lets it go. The snake eats all the insects it can find, including parasites that might hurt the baby owls. Then again, sometimes the nest is inhabited by tree ants that do the same thing, cleaning up all the parasites and scraps of leftover food while not bothering the owls.

If a predator grabs an elf owl, or a scientist nets and handles one, the owl pretends to be dead. A lot of times this will cause the predator to relax its jaw muscles, which often allows the owl to wiggle free and fly away. The scientists are a little more careful about relaxing their hands, but when a scientist handles an elf owl, it’s usually to do a quick examination and maybe put a leg band on for identification purposes, and then they let the owl go again anyway.

This is what an elf owl sounds like:

[elf owl call]

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 for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 338: Updates 6 and an Arboreal Clam!?!

This week we have our annual updates and corrections episode, and at the end of the episode we’ll learn about a really weird clam I didn’t even think was real at first.

Thanks to Simon and Anbo for sending in some corrections!

Further reading:

Lessons on transparency from the glass frog

Hidden, never-before-seen penguin colony spotted from space

Rare wild asses spotted near China-Mongolia border

Aye-Ayes Use Their Elongated Fingers to Pick Their Nose

Homo sapiens likely arose from multiple closely related populations

Scientists Find Earliest Evidence of Hominins Cooking with Fire

153,000-Year-Old Homo sapiens Footprint Discovered in South Africa

Newly-Discovered Tyrannosaur Species Fills Gap in Lineage Leading to Tyrannosaurus rex

Earth’s First Vertebrate Superpredator Was Shorter and Stouter than Previously Thought

252-Million-Year-Old Insect-Damaged Leaves Reveal First Fossil Evidence of Foliar Nyctinasty

The other paleo diet: Rare discovery of dinosaur remains preserved with its last meal

The Mongolian wild ass:

The giant barb fish [photo from this site]:

Enigmonia aenigmatica, AKA the mangrove jingle shell, on a leaf:

Show transcript:

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

This week is our annual updates and corrections episode, but we’ll also learn about the mangrove jingle shell, a clam that lives in TREES. A quick reminder that this isn’t a comprehensive updates episode, because that would take 100 years to prepare and would be hours and hours long, and I don’t have that kind of time. It’s just whatever caught my eye during the last year that I thought was interesting.

First, we have a few corrections. Anbo emailed me recently with a correction from episode 158. No one else caught this, as far as I can remember. In that episode I said that geckos don’t have eyelids, and for the most part that’s true. But there’s one family of geckos that does have eyelids, Eublepharidae. This includes the leopard gecko, and that lines up with Anbo’s report of having a pet leopard gecko who definitely blinked its eyes. This family of geckos are sometimes even called eyelid geckos. Also, Anbo, I apologize for mispronouncing your name in last week’s episode about shrimp.

After episode 307, about the coquí and glass frogs, Simon pointed out that Hawaii doesn’t actually have any native frogs or amphibians at all. It doesn’t even have any native reptiles unless you count sea snakes and sea turtles. The coqui frog is an invasive species introduced by humans, and because it has no natural predators in Hawaii it has disrupted the native ecosystem in many places, eating all the available insects. Three of the Hawaiian islands remain free of the frogs, and conservationists are working to keep it that way while also figuring out ways to get them off of the other islands. Simon also sent me the chapter of the book he’s working on that talks about island frogs, and I hope the book is published soon because it is so much fun to read!

Speaking of frogs, one week after episode 307, an article about yet another way the glass frog is able to hide from predators was published in Science. When a glass frog is active, its blood is normal, but when it settles down to sleep, the red blood cells in its blood collect in its liver. The liver is covered with teensy guanine crystals that scatter light, which hides the red color from view. That makes the frog look even more green and leaf-like!

We’ve talked about penguins in several episodes, and emperor penguins specifically in episode 78. The emperor penguin lives in Antarctica and is threatened by climate change as the earth’s climate warms and more and more ice melts. We actually don’t know all that much about the emperor penguin because it lives in a part of the world that’s difficult for humans to explore. In December 2022, a geologist named Peter Fretwell was studying satellite photos of Antarctica to measure the loss of sea ice when he noticed something strange. Some of the ice had brown stains.

Dr Fretwell knew exactly what those stains were: emperor penguin poop. When he obtained higher-resolution photos, he was able to zoom in and see the emperor penguins themselves. But this wasn’t a colony he knew about. It was a completely undiscovered colony.

In episode 292 we talked about a mystery animal called the kunga, and in that episode we also talked a lot about domestic and wild donkeys. We didn’t cover the Mongolian wild ass in that one, but it’s very similar to wild asses in other parts of the world. It’s also called the Mongolian khulan. It used to be a lot more widespread than it is now, but these days it only lives in southern Mongolia and northern China. It’s increasingly threatened by habitat loss, climate change, and poaching, even though it’s a protected animal in both Mongolia and China.

In February of 2023, a small herd of eight Mongolian wild asses were spotted along the border of both countries, in a nature reserve. A local herdsman noticed them first and put hay out to make sure the donkeys had enough to eat. The nature reserve has a water station for wild animals to drink from, and has better grazing these days after grassland ecology measures were put into place several years ago.

In episode 233 we talked about the aye-aye of Madagascar, which has weird elongated fingers. Its middle finger is even longer and much thinner than the others, which it uses to pull invertebrates from under tree bark and other tiny crevices. Well, in October of 2022 researchers studying aye-ayes started documenting another use for this long thin finger. The aye-ayes used it to pick their noses. It wasn’t just one aye-aye that wasn’t taught good manners, it was widespread. And I hope you’re not snacking while I tell you this, the aye-aye would then lick its finger clean. Yeah. But the weirdest thing is that the aye-aye’s thin finger is so long that it can potentially reach right through the nose right down into the aye-aye’s throat.

It’s pretty funny and gross, but wondering why some animals pick their noses is a valid scientific question. A lot of apes and monkeys pick their noses, as do humans (not that we admit it most of the time), and now we know aye-ayes do too. The aye-aye is a type of lemur and therefore a primate, but it’s not very closely related to apes and monkeys. Is this just a primate habit or is it only seen in primates because we have fingers that fit into our nostrils? Would all mammals pick their nose if they had fingers that would fit up in there? Sometimes if you have a dried snot stuck in your nose, it’s uncomfortable, but picking your nose can also spread germs if your fingers are dirty. So it’s still a mystery why the aye-aye does it.

A recent article in Nature suggests that Homo sapiens, our own species, may have evolved not from a single species of early human but from the hybridization of several early human species. We already know that humans interbred with Neandertals and Denisovans, but we’re talking about hybridization that happened long before that between hominin species that were even more closely related.

The most genetically diverse population of humans alive today are the Nama people who live in southern Africa, and the reason they’re so genetically diverse is that their ancestors have lived in that part of Africa since humans evolved. Populations that migrated away from the area, whether to different parts of Africa or other parts of the world, had a smaller gene pool to draw from as they moved farther and farther away from where most humans lived.

Now, a new genetic study of modern Nama people has looked at changes in DNA that indicate the ancestry of all humans. The results suggest that before about 120,000 to 135,000 years ago, there was more than one species of human, but that they were all extremely closely related. Since these were all humans, even though they were ancient humans and slightly different genetically, it’s probable that the different groups traded with each other or hunted together, and undoubtedly people from different groups fell in love just the way people do today. Over the generations, all this interbreeding resulted in one genetically stable population of Homo sapiens that has led to modern humans that you see everywhere today. To be clear, as I always point out, no matter where people live or what they look like, all people alive today are genetically human, with only minor variations in our genetic makeup. It’s just that the Nama people still retain a lot of clues about our very distant ancestry that other populations no longer show.

To remind everyone how awesome out distant ancestors were, here’s one new finding of how ancient humans lived. We know that early humans and Neandertals were cooking their food at least 170,000 years ago, but recently archaeologists found the remains of an early hominin settlement in what is now Israel where people were cooking fish 780,000 years ago. There were different species of fish remains found along with the remains of cooking fires, and some of the fish are ones that have since gone extinct. One was a carp-like fish called the giant barb that could grow 10 feet long, or 3 meters.

In other ancient human news, the oldest human footprint was discovered recently in South Africa. You’d think that we would have lots of ancient human footprints, but that’s actually not the case when it comes to footprints more than 50,000 years old. There are only 14 human footprints older than that, although there are older footprints found made by ancestors of modern humans. The newly discovered footprint dates to 153,000 years ago.

It wouldn’t be an updates episode without mentioning Tyrannosaurus rex. In late 2022 a newly discovered tyrannosaurid was described. It lived about 76 million years ago in what is now Montana in the United States, and while it wasn’t as big as T. rex, it was still plenty big. It probably stood about seven feet high at the hip, or a little over 2 meters, and might have been 30 feet long, or 9 meters. It probably wasn’t a direct ancestor of T. rex, just a closely related cousin, although we don’t know for sure yet. It’s called Daspletosaurus wilsoni and it shows some traits that are found in older Tyrannosaur relations but some that were more modern at the time.

Dunkleosteus is one of a number of huge armored fish that lived in the Devonian period, about 360 million years ago. We talked about it way back in episode 33, back in 2017, and at that time paleontologists thought Dunkleosteus terrelli might have grown over 30 feet long, or 9 meters. It had a heavily armored head but its skeleton was made of cartilage like a shark’s, and cartilage doesn’t generally fossilize, so while we have well-preserved head plates, we don’t know much about the rest of its body.

With the publication in early 2023 of a new study about dunkleosteus’s size, we’re pretty sure that 30 feet was a huge overestimation. It was probably less than half that length, maybe up to 13 feet long, or almost 4 meters. Previous size estimates used sharks as size models, but dunkleosteus would have been shaped more like a tuna. Maybe you think of tuna as a fish that makes a yummy sandwich, but tuna are actually huge and powerful predators that can grow up to 10 feet long, or 3 meters. Tuna are also much heavier and bigger around than sharks, and that was probably true for dunkleosteus too. The study’s lead even says dunkleosteus was built like a wrecking ball, and points out that it was probably the biggest animal alive at the time. I’m also happy to report that people have started calling it chunk-a-dunk.

We talked about trace fossils in episode 103. Scientists can learn a lot from trace fossils, which is a broad term that encompasses things like footprints, burrows, poops, and even toothmarks. Recently a new study looked at insect damage on leaves dating back 252 million years and learned something really interesting. Some modern plants fold up their leaves at night, called foliar nyctinasty, which is sometimes referred to as sleeping. The plant isn’t asleep in the same way that an animal falls asleep, but “sleeping” is a lot easier to say than foliar nyctinasty. Researchers didn’t know if folding leaves at night was a modern trait or if it’s been around for a long time in some plants. Lots of fossilized leaves are folded over, but we can’t tell if that happened after the leaf fell off its plant or after the plant died.

Then a team of paleontologists from China and Sweden studying insect damage to leaves noticed that some leaves had identical damage on both sides, exactly as though the leaf had been folded and an insect had eaten right through it. That’s something that happens in modern plants when they’re asleep and the leaves are folded closed.

The team looked at fossilized leaves from a group of trees called gigantopterids, which lived between 300 and 250 million years ago. They’re extinct now but were advanced plants at the time, some of the earliest flowering plants. They also happen to have really big leaves that often show insect damage. The team determined that the trees probably did fold their leaves while sleeping.

In episode 151 we talked about fossils found with other fossils inside them. Basically it’s when a fossil is so well preserved that the contents of the dead animal’s digestive system are preserved. This is incredibly rare, naturally, but recently a new one was discovered.

Microraptor was a dinosaur that was only about the size of a modern crow, one of the smallest dinosaurs, and it probably looked a lot like a weird bird. It could fly, although probably not very well compared to modern birds, and in addition to front legs that were modified to form wings, its back legs also had long feathers to form a second set of wings.

Several exceptionally well preserved Microraptor fossils have been discovered in China, some of them with parts of their last meals in the stomach area, including a fish, a bird, and a lizard, so we knew they were generalist predators when it came to what they would eat. Now we have another Microraptor fossil with the fossilized foot of a mammal in the place where the dinosaur’s stomach once was. So we know that Microraptor ate mammals as well as anything else it could catch, although we don’t know what kind of mammal this particular leg belonged to. It may be a new species.

Let’s finish with the mangrove jingle shell. I’ve had it on the list for a long time with a lot of question marks after it. It’s a clam that lives in trees, and I actually thought it might be an animal made up for an April fool’s joke. But no, it’s a real clam that really does live in trees.

The mangrove jingle shell lives on the mangrove tree. Mangroves are adapted to live in brackish water, meaning a mixture of fresh and salt water, or even fully salt water. They mostly live in tropical or subtropical climates along coasts, and especially like to live in waterways where there’s a tide. The tide brings freshly oxygenated water to its roots. A mangrove tree needs oxygen to survive just like animals do, but it has trouble getting enough through its roots when they’re underwater. Its root system is extensive and complicated, with special types of roots that help it stay upright when the tide goes out and special roots called pneumatophores, which stick up above the water or soil and act as straws, allowing the tree to absorb plenty of oxygen from the air even when the rest of the root system is underwater. These pneumatophores are sometimes called knees, but different species of mangrove have different pneumatophore shapes and sizes.

One interesting thing about the mangrove tree is that its seeds actually sprout while they’re still attached to the parent tree. When it’s big enough, the seedling drops off its tree into the water and can float around for a long time before it finds somewhere to root. If can even survive drying out for a year or more.

The mangrove jingle shell clam lives in tropical areas of the Indo-Pacific Ocean, and is found throughout much of coastal southeast Asia all the way down to parts of Australia. It grows a little over one inch long, or 3 cm, and like other clams it finds a place to anchor itself so that water flows past it all the time and it can filter tiny food particles from the water. It especially likes intertidal areas, which happens to be the same area that mangroves especially like.

Larval jingle shells can swim, but they need to find somewhere solid to anchor themselves as they mature. When a larva finds a mangrove root, it attaches itself and grows a domed shell. If it finds a mangrove leaf, since mangrove branches often trail into the water, it attaches itself to the underside and grows a flatter shell. Clams attached to leaves are lighter in color than clams attached to roots or branches. Fortunately, the mangrove is an evergreen tree that doesn’t drop its leaves every year.

So there you have it. Arboreal clams! Not a hoax or an April fool’s joke.

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 333: Robins and Ravens

Thanks to Liesbet, Simon, and Thea for their suggestions this week! Let’s learn about some birds!

Further reading:

Blue Tits and Milk Bottle Tops

Ravens parallel great apes in flexible planning for tool-use and bartering

Further watching:

A Raven Calling [this is a great video of a raven making all sorts of interesting sounds–I only used a tiny clip of it in the episode but it’s worth watching the whole thing]

The European robin:

The American robin and a worm that is having a very bad day:

A blue tit [photo By © Francis C. Franklin / CC-BY-SA-3.0, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=37675470]:

A blue tit about to get the cap off that milk bottle [photo from link above]:

The Eastern bluebird:

A raven:

An American crow:

Show transcript:

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

This week we have suggestions from Liesbet, Simon, and Thea, who suggested some relatively common birds that you may already think you know all about, but there’s lots to learn about them!

We’ll start with Liesbet’s suggestion, about the European robin and bluebird, and while we’re at it we’ll learn about the American robin and bluebird. The European and American birds are completely different species. The reason they have the same names is because when Europeans first started paying attention to the birds of North America, they needed names for the birds. The native peoples had names for them, of course, but the Europeans wanted names in a language they understood, so in a lot of cases they just borrowed names already in use at home.

Let’s start with the robin, which we also talked about way back in episode 81.

The European robin is a little bitty bird, only around 5 inches long, or 13 cm, with a brown back, streaked gray or buff belly, and orange face and breast. It has a short black bill and round black eyes. It eats insects, worms, berries, and seeds. The eggs are pale brown with reddish speckles.

It lives throughout much of Eurasia, but robins in Britain tend to be fairly tame, probably because they were traditionally considered beneficial in Britain and Ireland, so farmers and gardeners wouldn’t hurt them. In other parts of Europe they were hunted and are much more shy. European robins are also common on Christmas cards in Britain and Ireland, possibly because in the olden days, postmen used to wear red jackets. The postmen started to be called robins as a result, and since postmen bring Christmas cards, the bird robin became linked with card delivery and finally just ended up on the Christmas cards. Plus, their orange markings are cheerful in winter.

This is what the European robin sounds like:

[robin song]

The American robin is a type of thrush. It lives year-round in most of the United States and parts of Mexico, spends summers in much of Canada, and winters in parts of Mexico. It’s very different from the European robin. The European robin is tiny and round and adorable, while the American robin is big and always looks kind of angry. It grows around 10 inches long, or 25 cm. It’s dark gray on its back, with a rusty red breast, white undertail coverts, and a long yellow bill. It also has white markings around its eyes. Young birds are speckled. It mostly eats insects, worms, and berries.

If you see a bird on the ground, running quickly and then stopping, it’s probably a robin. Mostly the robin hunts bugs by sight, but it has good hearing and can actually hear worms moving around underground. You can sometimes see a robin with its head cocked, listening for a worm, before pouncing and pulling it out of the ground, just like in a cartoon.

American robin eggs are a light teal blue, so common and well-known that robin’s-egg-blue is a typical description of that particular color. In the spring after eggs hatch, the mother robin will carry the eggshells away from the nest to drop them, so predators won’t see the shells and know there’s a nest nearby. That’s why you’ll sometimes see half a robin eggshell on the sidewalk. It doesn’t mean something bad happened to the baby, just that the mother bird is doing her job. Both parents feed the chicks, and the parents also carry off the babies’ droppings to scatter them away from the nest.

This is what an American robin’s song sounds like.

[robin song]

Liesbet also wanted to learn about the European bluebird, more commonly called the Eurasian blue tit. We haven’t talked about it or the American bluebird before, even though they’re both beautiful birds.

The blue tit lives throughout Europe and parts of western Asia. It grows around 4 and a half inches long, or 12 cm, and has a bright blue crown on its head with blue on its wings, tail, and back. Its face is mostly white but it has a black streak that crosses its eye and a black ring around its neck. In fact, if you’re familiar with the blue jay of North America, the blue tit looks a lot like a miniature blue jay. It even has a little bit of a crest that it can raise and lower.

Because it eats a lot of insects and other small invertebrates, along with some seeds, the blue tit is an acrobatic bird. It will hang upside down from a twig to reach a caterpillar on the underside of a leaf, that sort of thing. It will also peel bits of bark away from a tree trunk to find tiny insects and spiders hiding underneath it. This habit leads it to sometimes peel bits off of people’s houses, like the putty that holds windowpanes in place. It also once led to the blue tit learning a surprising way to find food, and to learn about that, we have to learn a little bit about how people in the olden days got their milk if they didn’t own cows.

Back in the early 20th century, people used to get milk delivered every morning by a milkman. Refrigerators and ice boxes weren’t common like they are today, and most people didn’t have a way to keep milk cold. That meant it would go bad very quickly, so people would just order how much milk they needed in one day and when they got up in the morning, the milkman would have left the milk and other dairy products on the doorstep for the family.

The milk was always whole milk, also called full-fat, and as it sat in its bottles on the doorstep waiting for the family to wake up and bring the milk in, the cream would separate and rise to the top of the milk. Cream is just the fattiest, richest part of the milk. These days milk is processed differently so even if you buy whole milk, the cream won’t separate from it, and most milk sold today has already had most of the cream separated out. That’s why skim milk is called that, because the cream has been skimmed off the top. It’s sold separately as heavy whipping cream or mixed with milk as half-and-half. But back in the olden days, if you wanted to make whipped cream or clotted cream or some other recipe that calls for cream, you’d just skim the cream off yourself to use it.

The problem is, cream is so rich and full of protein that other animals learned to rob milk bottles, especially the blue tit. Birds can’t digest milk, naturally, since only mammals produce milk and are adapted to digest it, and even most adult mammals have trouble digesting milk. But cream contains a lot less lactose than the milk itself, and lactose is the type of sugar in milk that can cause stomach upset in adults. Blue tits learned that if they peeled the little foil cap off a milk bottle, they could get at the cream, and it became such a widespread behavior that each generation of blue tits became more adapted to digest cream.

These days, of course, most people buy their milk at the grocery store. The blue tits have had to go back to eating bugs and seeds.

This is what a blue tit sounds like:

[blue tit song]

The bluebird is a North American bird that also eats insects and other small invertebrates, along with berries and seeds. It grows around 7 inches long, or 18 cm. There are three species, the eastern bluebird and western bluebird, which look similar with bright blue above and white underneath with rusty red breast, and the mountain bluebird, which is blue almost all over and lives in mountainous areas of western North America. The bluebird is a type of thrush, meaning that it’s actually related to the American robin and used to be called the blue robin.

The bluebird spends a lot of its time sitting on a branch and watching for insects in the grass below. When it spots a grasshopper or beetle or spider or even a snail, it will drop down from its branch to grab it. It prefers open grasslands with trees or brush it can perch in, so it’s common around farmland. The mountain bluebird hunts like this too, but it doesn’t always bother to perch and will just hover above the ground until it spots a bug.

This is what an eastern bluebird sounds like:

[bluebird song]

Next, Simon and Thea wanted to learn about crows and ravens. The raven is another bird we covered a long time ago, in episode 112. I had a really bad cold the week of that episode and not only did I sound awful, I didn’t do a very good job with my research. I’m glad to revisit the topic and correct a few mistakes.

Crows and ravens look similar and are closely related, with both belonging to the genus Corvus. There are lots of species and subspecies of both, but let’s talk specifically about the American crow since it’s closely related to the hooded crow and the carrion crow found throughout Europe and Asia. Likewise, we’ll talk about the common raven since it’s found throughout much of the northern hemisphere.

The American crow can grow up to about 20 inches long, or 50 cm, with a wingspan over 3 feet across, or about a meter. Meanwhile, the common raven has a wingspan of up to 5 feet across, or 1.5 meters, and can grow up to 26 inches long, or 67 cm. Both are glossy black all over with large, heavy bills and long legs.

Crows and ravens both mate for life. Crows in particular are devoted family birds, with the grown young of a pair often staying to help their parents raise the next nest.

Both crows and ravens are omnivores, which means they eat pretty much anything. They will eat roadkill and other carrion, fruit and grain, insects, small animals, other birds, and eggs. They’re also extremely smart, which means a crow or raven can figure out how to get into trash cans and other containers to find food that humans think is secure.

Both also sometimes make and use tools, especially sticks that they use to dig out insects in places where their beaks can’t reach. But ravens in particular show a lot of tool use. Ravens sometimes throw pinecones or rocks at people who approach too close to their nests, and will even use sticks to stab at attacking owls. A few ravens have been observed to hold big pieces of bark in their feet while flying in strong winds, and they use the bark as a sort of rudder to help them maneuver. Other cognitive studies of ravens show that they have sophisticated and flexible problem-solving abilities where they can plan at least one step ahead, similar to great apes. Other corvids show similar abilities.

The raven can imitate other animals and birds, even machinery, in addition to making all sorts of calls. It can even imitate human speech. If a raven finds a dead animal but isn’t strong enough to open the carcass to get at the meat, it may imitate a wolf or fox to attract the animal to the carcass. The wolf or fox will open the carcass, and even after it eats as much as it wants, there’s plenty left for the raven.

Ravens also communicate non-vocally with other ravens. A raven will use its beak to point with, the way humans will point with a finger. They’ll also hold something and wave it to get another raven’s attention, which hasn’t been observed in any other animal besides apes.

The raven is much larger and heavier than a crow, and you can also distinguish a crow from a raven by their calls. This is what an American crow sounds like:

[crow call]

And this is what a raven sounds like:

[raven call]

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 332: Hunting Partners and Mutualism

Thanks to Vaughn and Jan for their suggestions this week! We’re going to learn about mutualism of various types.

Further reading:

The odd couple: spider-frog mutualism in the Amazon rainforest

What Birds, Coyotes, and Badgers Know About Teamwork

Octopuses punch fishes during collaborative interspecific hunting events

An Emotional Support Dog Is the Only Thing That Chills Out a Cheetah

Buddies [picture from the first link above]:

The honeyguide bird:

Cheetahs and dogs can be friends:

Show transcript:

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

This week we’re going to learn about a topic that I’ve been wanting to cover for a long time, mutualism. It’s a broad topic so we won’t try to cover everything about it in this episode, just give an overview with some examples. Vaughn suggested symbiotic behavior ages ago, and Jan gave me a great example of this, also ages ago, so thanks to both of them!

Mutualism is similar to other terms, including symbiosis, often referred to as “a symbiotic relationship.” I’m using mutualism as a general term, but if you want to learn more you’ll quickly find that there are lots of terms referring to different interspecies relationships. Basically we’re talking about two unrelated organisms interacting in a way that’s beneficial to both. This is different from commensalism, where one organism benefits and the other doesn’t but also isn’t harmed, and parasitism, where one organism benefits and the other is harmed.

We’ll start with the suggestion from Jan, who alerted me to this awesome pair of animals. Many different species have developed this relationship, but we’ll take as our specific example the dotted humming frog that lives in parts of western South America.

The dotted humming frog is a tiny nocturnal frog that barely grows more than half an inch long from snout to vent, or about 2 cm. It lives in swamps and lowland forests and spends most of the day in a burrow underground. It comes out at night to hunt insects, especially ants. It really loves ants and is considered an ant specialist. That may be why the dotted humming frog has a commensal relationship with a spider, the Colombian lesserblack tarantula.

The tarantula is a lot bigger than the frog, with its body alone almost 3 inches long, or 7 cm. Its legspan can be as much as 8 and a half inches across, or 22 cm. It’s also nocturnal and spends the day in its burrow, coming out at night to hunt insects and other small animals, although not ants. It’s after bigger prey, including small frogs. But it doesn’t eat the dotted humming frog. One or even more of the frogs actually lives in the same burrow as the tarantula and they come out to hunt in the evenings at the same time as their spider roommate.

So what’s going on? Obviously the frog gains protection from predators by buddying up with a tarantula, but why doesn’t the tarantula just eat the frog? Scientists aren’t sure, but the best guess is that the frog protects the spider’s eggs from ants. Ants like to eat invertebrate eggs, but the dotted humming frog likes to eat ants, and as it happens the female Colombian lesserblack tarantula is especially maternal. She lays about 100 eggs and carries them around in an egg sac. When the babies hatch, they live with their mother for up to a year, sharing food and burrow space.

This particular tarantula also gets along with another species of frog that also eats a lot of ants. Researchers think the spiders distinguish the frogs by smell. The ant-eating frogs apparently smell like friends, or at least useful roommates, while all other frogs smell like food. Or, of course, it’s possible that the ant-eating frogs smell and taste bad to the spider. Either way, both the frogs and the tarantulas benefit from the relationship–and this pairing of tiny frogs and big spiders is one that’s actually quite common throughout the world.

Mutualism is everywhere, from insects gathering nectar to eat while pollenating flowers at the same time, to cleaner fish eating parasites from bigger fish, to birds eating fruit and pooping out seeds that then germinate with a little extra fertilizer. Many mutualistic relationships aren’t obvious to us as humans until we’ve done a lot of careful observations, which is why it’s so important to protect not just a particular species of animal but its entire ecosystem. We don’t always know what other animals and plants that animal depends on to survive, and vice versa.

Sometimes an individual animal will work together with an individual of another species to find food. This may not happen all the time, just when circumstances are right. Sometimes, for example, a coyote will pair up with a badger to hunt. The coyote is closely related to wolves and can run really fast, while the American badger can dig really fast. Both are native to North America. They also both really like to eat prairie dogs, a type of rodent that can run really fast and lives in a burrow. Some prairie dog tunnels can extend more than 30 feet, or 10 meters, with multiple exits. The badger can dig into the burrow and if the prairie dog leaves through one of the exits, the coyote chases after it. When one of the predators catches the prairie dog, they don’t share the meal but they will often continue to hunt together until both are able to eat.

Other animals hunt together too. Moray eels will sometime pair up with a fish called the grouper in a similar way as the coyote and badger. The grouper is a fast swimmer while the eel can wriggle into crevices in rocks or coral. The grouper will swim up to the eel and shake its head rapidly to initiate a hunt, and if the grouper has seen a prey item disappear into a crevice, it will lead the eel to the crevice and shake its head at it again.

Groupers also sometimes pair up with octopuses to hunt together, as will some other species of fish. Like the eel, the octopus can enter crevices to chase an animal that’s trying to hide. But the octopus isn’t always a good hunting partner, because if the grouper catches a fish, sometimes the octopus will punch the grouper and steal its fish. Not cool, octopus.

Birds have mutualistic relationships too, including the honeyguide that lives in parts of Africa and Asia. It’s a little perching bird that’s mostly gray and white or brown and white, with the males of some species having yellow markings. It eats insects, spiders, and other invertebrates, and it especially likes bee larvae. But it’s just a little bird and can’t break open wild honeybee hives by itself.

Some species of honeyguide that live in Africa have figured out that humans can break open beehives. When the honeyguide bird finds a beehive, it will fly around until it hears the local people’s hunting calls. The bird will then respond with a distinct call of its own, alerting the people, and will guide them to the beehive. This has been going on for thousands of years. The humans gather the honey, the honeyguide feasts on the bee larvae and wax, and everyone has a good day except the bees.

The honeyguide is also supposed to guide the honey badger to beehives, but there’s no definitive evidence that this actually happens. Honey badgers do like to eat honey and bee larvae, though, and when a honey badger breaks open a beehive, honeyguides and other birds will wait until it’s eaten what it wants and will then pick through the wreckage for any food the badger missed. But the honeyguide might lead the honey badger to the hive, we just don’t know for sure.

Humans sometimes even help other animals into a commensal relationship. Vaughn gave me an example of a cheetah in a zoo who became best friends with a dog. This hasn’t just happened once, it’s happened lots of times because zookeepers have found that it helps cheetahs kept in captivity. Cheetahs are social animals but sometimes a zoo doesn’t have a good companion for a cheetah cub. The cub could be in danger from older, unrelated cheetahs, but a cheetah all on its own is prone to anxiety. It’s so important for a cheetah to have a sibling that if a mother cheetah only has one cub, or if all but one cub dies, a lot of times she’ll abandon the single cub. If this happens in the wild, it’s sad, but if it happens in captivity the zoo needs to help the cub.

To do this, the zoo will pair the cub with a puppy of a sociable, large breed of dog, such as a Labrador or golden retriever. The cub and the puppy grow up together. The cheetah has a mellow friend who helps alleviate its anxiety, and the dog has a friend who’s really good at playing chase.

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 just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us that way.

Thanks for listening!

Episode 326: The Harpy Eagle and Friends

Thanks to Eva and Anbo for suggesting the harpy eagle!

Further reading:

Crested Eagle Feeding a Post-Fledged Young Harpy Eagle

Harpy eagle with a food [By http://www.birdphotos.com – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=3785263]:

The harpy eagle has great big feet and talons:

The harpy eagle with its feather crown raised [photo by Eric Kilby]:

The New Guinea harpy eagle looks similar to its South American cousin [By gailhampshire from Cradley, Malvern, U.K – New Guinea Harpy Eagle. Harpyopsis novaeguineae, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=86187611]:

Ruppell’s griffon vulture:

Show transcript:

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

We’ve been talking about a lot of mammals lately, so let’s have an episode about birds. Anbo suggested the harpy eagle not too long ago, and a much longer time ago Eva suggested the harpy eagle and other raptors.

The word raptor can be confusing because it refers to a type of small theropod dinosaur as well as a type of bird. When referring to a bird, the term raptor includes eagles, hawks, vultures, owls, and other birds of prey. And that includes the harpy eagle.

The harpy eagle lives throughout much of Central and South America, although not as far south as Patagonia. It has a wingspan up to about seven feet across, or over 2 meters, and like other raptors, females are larger than males. This isn’t an especially big wingspan for an eagle, but that’s because the harpy eagle hunts in forests and needs short, broad wings that allow it to maneuver through branches.

The harpy eagle is a beautiful bird. It has a light gray head and darker gray or black body, and is white underneath with delicate black stripes on its leg feathers, with broader stripes on its tail and wings. It has a black ring around its neck, huge yellow feet with enormous talons, and a black bill. Each talon, which is the term for a raptor’s claws, can be over 5 inches long, or 13 cm, while its feet in general are bigger than a grown man’s hand, even if the man has especially big hands.

Most striking of all is the harpy eagle’s crest, also sometimes referred to as a crown. The crown is made of long, rounded feathers and most of the time they don’t show very much. When a harpy eagle is alarmed, it raises the feather crown and poofs out the feathers on its face, which makes its head look bigger and sort of owl-shaped.

The harpy eagle mostly lives in lowland rainforests. It mates for life and doesn’t have babies every year. Every two or three years a harpy eagle pair will build a huge nest out of sticks in the top of the tallest tree they can find. The female lays two eggs, which the parents care for together. The female spends most of her time incubating the eggs while the male brings her food, although he will also take a turn incubating while she goes out to stretch her wings and do a bit of hunting herself. When the first egg hatches, the parents bring the baby lots of food and give it lots of attention–but they ignore the other egg at that point, which usually doesn’t hatch as a result. A harpy eagle chick is all white at first, and although it can fly at around 6 months old, its parents will keep feeding it for almost another year.

The harpy eagle is increasingly threatened due to habitat loss and poaching. Because it’s such a big bird, many people shoot it because they think it’s dangerous to livestock or children. But it mostly eats monkeys, sloths, kinkajous and coatis, iguanas, and other medium-sized animals. It’s rare that it attacks livestock since it mostly hunts within the tree canopy for arboreal animals. If your lambs and chickens are sitting on tree branches, you already have a bigger problem than harpy eagles eating them.

A captive breeding program has been started in various zoos around the world, while conservationists work to protect the harpy eagle’s natural habitat so that individuals can be released back into the wild.

We don’t actually know all that much about the harpy eagle, but we know even less about its close relation, the New Guinea harpy eagle. It resembles the harpy eagle but instead of being mostly gray and white, it’s mostly brown and cream in color. It has longer legs and tail but is smaller overall than the harpy eagle, with a wingspan closer to 5 feet across, or 1.5 meters. It has a smaller crest than the harpy eagle too.

Like its South American cousin, the New Guinea harpy eagle hunts in forests, especially rainforests, and spends most of its time perched in a tree, watching for small animals to happen by. Sometimes it will shake a branch to startle any animals in the area to run or fly away, at which point the eagle flies after them. It will even climb around in a tree and poke around in any potential hiding places it finds. It eats tree kangaroos, possums, and other small to medium-sized mammals, but it also eats a lot of birds and reptiles.

While it’s closely related to the harpy eagle, the New Guinea harpy eagle is placed in a different genus. This is also the case for another closely related bird, the crested eagle, which lives in parts of South America. It’s a little smaller than the harpy eagle of South America, with a wingspan of not quite 6 feet across, or 1.8 meters, with a black mask marking over its eyes and a black spot on its crest. Other than that it’s mostly gray.

The two species look enough alike that sometimes people confuse the crested eagle for a young harpy eagle where their ranges overlap. But in at least one documented case, the birds seemingly got confused too.

In early 2004, a team of scientists observing a harpy eagle nest noticed something odd. The nest had one baby in it that was about a month old when the scientists first observed it, and they noticed a crested eagle perched nearby. Every time the scientists visited the nest, the crested eagle seemed to be nearby, although the harpy eagle parents were also around and seemed just fine. The scientists observed the crested eagle adding branches to the nest and even bringing food to the harpy eagle baby. This continued for almost a year. The baby actively solicited food from the crested eagle and happily ate what it brought. At the same time, the harpy eagle parents allowed the crested eagle to approach, although generally the crested eagle didn’t come very close when the harpy eagle parents were around.

The scientists published a short paper about these observations in 2006, including a few hypotheses about the crested eagle’s behavior. They suggested that the crested eagle might have lost her own chick and transferred her maternal instincts to another eagle chick nearby, or she might have just been responding to the eagle chick’s requests for food. She might even have wanted to use that tree for her own nest, but when the bigger, stronger harpy eagles moved in, she abandoned her nest but hung around. A male crested eagle wasn’t observed, so it’s also possible she had lost her mate.

Sometimes different species of raptor do feed each other’s nestlings, although we don’t know why. It also occasionally happens with other types of birds, often male birds whose own nests are still being incubated by the female or by birds whose nest is very close to another nest with babies in it.

Another raptor that hunts animals that live in trees is the crane hawk, also from South America. It lives in forests that are near water and usually hunts by sitting in a tree and watching for potential prey. A lot of the time, though, it hunts like the New Guinea harpy eagle, climbing around in a tree and poking through any nooks and crannies to find animals that are hiding. In the case of the crane hawk, though, it actually has double-jointed legs that allow it to reach a foot into a little hole in a tree to grab prey. Most birds don’t have legs that are flexible enough to allow this behavior. The crane hawk eats a lot of nestling birds, bats, frogs, and other small animals that hide in tree cavities, including some larger invertebrates like cicadas and snails. The only other raptor known to both hunt like this and have double-jointed legs is a genus of African harrier-hawks that aren’t related to the crane hawk. Yes, it’s convergent evolution, at it again!

Let’s get out of the trees now and finish with another raptor Eva suggested. We talked about Ruppell’s griffon vulture in episode 159, but only very briefly.

Ruppell’s griffon vulture is a critically endangered vulture that lives in parts of central and eastern Africa. Unlike the raptors we’ve talked about so far in this episode, it spends a lot of its time soaring at high elevations, so it has really big wings. Its wingspan is as much as 8 and a half feet across, or 2.6 meters. It’s mostly brown and black and like other vultures, it doesn’t have feathers on its head, just a little bit of thin fluff. It will travel enormous distances to find the dead animals it eats, sometimes following herds of migrating animals to scavenge individuals that die of injury or illness. It doesn’t just eat the yummy soft parts of a carcass, it will also eat bones and even the hide of a dead animal. It has a long neck that helps it get to the best bits of its food, uh, from the inside of the carcass. It sometimes even climbs completely inside the rib cage of a dead animal to more easily get every scrap of food.

The way vultures eat is gross, which makes it fun for me to talk about, but vultures are incredibly important. They actually help stop the spread of diseases like rabies and anthrax by eating animals that died of the diseases. The vulture’s digestive tract is so effective that it kills off any viruses that caused the animals to die.

Ruppell’s vulture mates for life. It nests in cliffs, with hundreds of vulture pairs nesting very close together. The female lays one egg, and both parents take care of the baby when it hatches. Even after it can fly, the parents take care of their chick for almost a year while it learns how to find food on its own. Most vultures have relatively weak feet since they don’t use them to catch prey like other raptors, but Ruppell’s vulture has strong feet to help it perch on the cliffs where it nests.

Ruppell’s griffon vulture is one of the highest-flying birds known. It’s been recorded flying as high as 37,000 feet, or 11,300 meters, and we know it was flying at 37,000 feet because unfortunately it was sucked into a jet engine and killed. There’s so little oxygen at that height that a human would pass out pretty much instantly, but the vulture’s blood contains a variant type of hemoglobin that’s more efficient at carrying oxygen than ordinary hemoglobin.

As if all that weren’t enough for one bird, Ruppell’s vulture can also live to be 50 years old. That’s pretty good for an animal that mostly eats rotting and diseased meat.

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 321: Archaeopteryx

We have merch available again!

Thanks to Eilee for suggesting this week’s topic, Archaeopteryx!

Further reading:

Dinosaur feather study debunked

Archaeopteryx fossil provides insights into the origin of flight

An Archaeopteryx fossil [By H. Raab (User: Vesta) – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=8066320]:

Show transcript:

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

We’ve had a lot of mammal episodes lately, so this week let’s learn about a reptile…uh, a bird. Not quite a bird, not exactly a reptile. That’s right, it’s an episode about archaeopteryx, a suggestion by Eilee!

A quick note before we start to say that I finally got around to setting up merch again if you want to order a t-shirt or water bottle or whatever with the podcast’s logo on it. I’m using Redbubble this time because they have a lot more items available than our previous vendor. There’s a link in the show notes.

We also have new stickers and those are free, so if you want one, just drop me an email and let me know what your mailing address is. The new sticker is a drawing of a capybara made by me. Anyway, on to the archaeopteryx!

The first archaeopteryx fossils were discovered in Germany in 1861. Before the first skeleton of an archaeopteryx was discovered, though, a single feather impression was found in a limestone quarry that has produced a lot of spectacularly well-preserved fossils. When the full specimen turned up later that same year, palaeontologists decided the feather came from the same animal.

That decision has been questioned repeatedly over the years. A study conducted with laser imaging determined that the single feather was different from the feathers of other archaeopteryx specimens. Results of that study were published in 2019, but in October of 2020 results of a study conducted with a specialized electron microscope determined that the feather did come from an archaeopteryx. The 2020 study also found that the feather was black.

Archaeopteryx lived around 150 million years ago in what is now Europe. It was about the size of a crow but while it looked a lot like a bird, it also looked a lot like a little dinosaur. It had small teeth and a long lizard-like tail. Of the twelve Archaeopteryx fossils found so far, all but one have feather impressions that indicate it had flight feathers on its arms, or rather wings, but at least one specimen also had flight feathers on its legs, which are sometimes referred to as hind wings. These hind wings would have helped it maneuver through branches even though its front wings were limited in their range of motion. It was probably a slow flyer that ate whatever small animals it could catch.

The wing feathers of archaeopteryx were very similar to those of modern birds, and a study published in late 2020 discovered another similarity. Birds molt their feathers and replace them the same way mammals shed hairs and regrow them, but it’s a little trickier for birds. A bird that loses too many feathers from its wings can’t fly until new feathers grow in. Modern birds solve this issue by molting only one pair of wing feathers at a time, and once the replacement grows in, the next pair is shed. The study examined fossilized archaeopteryx wings using a process called laser-stimulated fluorescence imaging, which can reveal details that aren’t otherwise visible. It discovered feather sheaths hidden under what would have been the skin of the wings, ready to grow new feathers. The feather sheaths were the same on both wings and resembled the molting pattern seen in modern falcons.

Archaeopteryx also had feathers on the rest of its body, but they aren’t well preserved so paleontologists can’t determine too much about them. They might have been more fluffy than sleek, like the soft downy feathers in young modern birds, or it might be that the fluffy feathers just happened to be the ones that were most preserved.

Palaeontologists study archaeopteryx because it gives us so much information about how birds evolved from dinosaurs. Archaeopteryx was still very much a dinosaur even though it looked superficially like a bird. Microscopic examination of the fossilized cells and blood vessels inside its bones show that it actually grew very slowly. Modern birds grow extremely quickly when they’re young. One scientist pointed out that when you watch a flock of pigeons, you can’t really tell which ones are fully grown and which ones are still quite young, because baby pigeons grow to an adult size so quickly. Dinosaurs grew to their adult size much more slowly, even the small carnivorous dinosaurs that were ancestral to modern birds. The study determined that Archaeopteryx would probably have taken almost three years to grow to its adult size.

The Archaeopteryx fossil called “specimen number eight” was determined to be a different species from the others, in a study published in 2018. It’s about half a million years younger than the other known specimens and has characteristics found in modern birds that the others don’t have. Its adaptations would have made it a better, more efficient flyer. The differences weren’t noticed before because it’s not a very good specimen and many of the bones are damaged and still embedded in the rock where they can’t be seen. The study used a process called synchrotron microtomography to basically take a 3D scan of the fossil and its rock matrix so scientists can study the scan without breaking the rock open and destroying parts of the fossil.

At the time that archaeopteryx lived, the sea levels were much higher than they are now and Europe was mostly a series of large islands in a shallow sea. The part of Europe that’s now Germany was subtropical but fairly dry, without much rain. All the archaeopteryx specimens have been found in limestone that was once mud at the bottom of a placid lagoon, protected from ocean currents and waves by small islands covered with shrubby vegetation. Archaeopteryx probably lived on these small islands, and while we don’t know how it behaved, many paleontologists think it may have hunted both by running on its long hind legs and by flying, just like a lot of birds do today. We have fossilized remains of little lizards and insects that would have made good meals for a hungry archaeopteryx.

What we do know is that sometimes an archaeopteryx had a very bad day and ended up drowning in the lagoon. On rare occasions, the body floated around until it decomposed enough that it sank into the mud at the bottom. Over millions of years, this mud turned into fine-grained limestone that preserved the fossil archaeopteryx remains in incredible detail.

For a long time, people thought archaeopteryx was a so-called missing link between dinosaurs and birds, and that it was the first bird. We now know that isn’t true. There were other bird-like dinosaurs that could fly before archaeopteryx evolved, although archaeopteryx was a very early flying avian dinosaur.

More importantly, we now know that birds are basically very derived dinosaurs. Dinosaurs had so many features we associate with birds, and birds still have so many features we associate with dinosaurs, that it’s hard to decide whether an animal like archaeopteryx was a bird-like dinosaur or a dinosaur-like bird. I guess it was sort of both.

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 313: The Wolverine and the Kakapo

This week we learn about two interesting animals from opposite parts of the world! Thanks to Felix and Jaxon for suggesting the wolverine and the kakapo.

Further reading:

Study: Wolverines need refrigerators

Kakapo Comeback [this article has some fantastic pictures!]

The wolverine likes cold weather:

So many young kakapos!

The kakapo is a really big bird:

(Photo by Matu Booth)

Show transcript:

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

This week we’re going to cover two animals suggested by listeners who spell their names with an X. I had already picked out these topics from the list and just now noticed both suggesters have X’s in their names. Thanks to Jaxon and Felix for these suggestions!

First, Felix suggested we learn about the wolverine. We’ve talked about it before in episode 62, but there’s a whole lot more to learn about this uncommon animal.

The wolverine is a mustelid, which is a family that includes weasels, ferrets, and other small, long, skinny animals with short legs. But the wolverine is big and broad, although its legs are pretty short. It kind of looks like a small bear and stands about 18 inches tall at the shoulder, or 45 cm. It’s light brown with darker brown or black legs, muzzle, tail, and back, and some have silvery-gray markings too. Its tail is short but fluffy. It lives in cold, mountainous areas, including northern Canada and Alaska, Siberia, and parts of Norway, Sweden, and Finland.

The wolverine is mainly a scavenger of animals that are already dead, but it will also kill and eat pretty much anything it can catch. This includes rabbits, mice, rats, porcupines, geese, and other small or relatively small animals, but it sometimes kills animals a lot bigger than it is, like deer. It will also eat eggs, berries, seeds, and anything else it can find. It’s not a picky eater.

The wolverine nearly went extinct in the 19th century due to overhunting for its fur, which is mostly waterproof and frost-proof. People used it to line winter clothes. The wolverine is also vulnerable to habitat loss and climate change, since it needs deep snow and cold temperatures to survive.

Because the wolverine lives where winters are harsh, when it finds a lot of food, it will sometimes bury it in snow to eat later. It chooses a protected area between boulders or a natural crevice in rocks to put the dead animal, then covers it with deep snow to keep it fresh for longer, just like putting meat in a freezer. Females in particular need this stored food, because they give birth in winter and need lots of food so they can produce milk for their babies.

But if you’ve ever taken food out of the freezer, you know it’s hard as a rock. How does the wolverine eat meat that’s frozen solid? Not only does the wolverine have strong jaws and teeth, it actually has a special tooth in the back of the mouth that points inward, one on each side of the upper jaw. The inward-pointing tooth allows the wolverine to tear off chunks of frozen meat more easily. Other mustelids have this arrangement of teeth too.

A male wolverine roams widely through a large territory, which can sometimes be hundreds of square miles. Pairs often mate for life although they don’t spend a lot of time together, and sometimes a male will have two or three mates. In winter, the female digs a den deep into the snow to have her babies, and while she mostly takes care of them by herself, the father wolverine will visit from time to time and bring everyone food. The babies stay with their mother for up to a year, and sometimes the half-grown wolverines will go traveling with their dad for a while.

The wolverine is sometimes called the nasty cat because it has a strong smell, which it uses to mark its territory. “Nasty cat” is the funniest name for an animal I’ve ever heard.

Next, Jaxon suggested the kakapo, which is a weird and adorable bird. It’s flightless and nocturnal, lives only in New Zealand, and is a type of parrot. A flightless, nocturnal parrot!

The kakapo is really big even for a parrot. It can grow over two feet long, or 64 cm, but since it’s flightless its wings and tail aren’t very big. Its legs are relatively short considering it has to walk everywhere. It has green feathers with speckled markings, blue-gray feet, and discs of feathers around its eyes that make its face look a little like an owl’s face. That’s why it’s sometimes called the owl parrot. Males are almost twice the size of females on average.

The kakapo evolved on New Zealand where it had almost no predators. A few types of eagle hunted it during the day, which is why it evolved to be mostly nocturnal. Its only real predator at night was one type of owl. As a result, the kakapo was one of the most common birds throughout New Zealand when humans arrived.

The Maori discovered New Zealand around 700 years ago. They killed the kakapo to eat and to use its feathers in clothing, and they also brought dogs and the Polynesian rat that also liked to kill and eat the kakapo. Then a few hundred years ago Europeans arrived, bringing all sorts of invasive animals with them, and they also chopped down forests to create more farmland.

By the end of the 19th century, the kakapo was becoming increasingly rare everywhere. When Resolution Island was declared a nature reserve in 1891, early conservationists brought kakapos and kiwis to the island in an attempt to save them. But stoats and feral cats killed them all. Attempts to establish captive breeding programs weren’t successful either. By 1970, scientists worried that the kakapo was already extinct.

Fortunately, a few of the birds survived in remote areas. By now conservationists understood that they had to provide a safe environment for the birds, and that took a lot of effort. Several islands were chosen as kakapo refuges, and then all the introduced mammals on the islands had to be eradicated or relocated. This included animals like deer that ate the same plants that the kakapo relied on, as well as predators. Then native plants and trees had to be transplanted to the islands since they’d been mostly killed off by deer and other introduced animals.

Then, finally, all the kakapos scientists could find were relocated to the islands. There weren’t very many, and most of them were males. 65 birds were introduced to four islands and monitored carefully, both to make sure they settled in well and to make sure no predators found their way to the islands.

Kakapo females only lay eggs when they have plenty of high-protein food, especially the fruit of the rimu tree that only ripens every four or five years, so the females were given extra food to encourage them to breed more often. The extra food helped, but it turns out that when the females were allowed to eat as much as they wanted, most of the eggs they laid hatched male chicks. That was the opposite of what the kakapo needed, so conservationists experimented with the amounts of extra food they gave the birds until finally the eggs were hatching equal numbers of females and males.

Many parrot species mate for life and both parents help take care of the eggs and babies, but the kakapo handles things differently. Males gather on hilltops during breeding season and each male digs out a shallow bowl well apart from other males, sometimes several bowls connected with little trails. If a male gets too close to another male, they’ll fight. Each male stands in his bowl and makes a booming call by inflating a special sac in his throat. The bowl helps amplify the sound and often the male will construct his bowl near a surface that reflects sound, like rock. His calls can be heard three miles away in good conditions, or 5 km, and the sound attracts females.

This system of males competing in one area to attract females is called lekking, spelled L-E-K. We’ve actually talked about lekking before but I don’t remember if I specifically mentioned the term. The area where the males gather is called a lekking ground or an arena or sometimes just a lek. The females walk around inspecting each male, who booms and struts to show how strong and fit he is. If a female is especially interested in one male, she’ll approach him and he starts his courtship dance. This sounds fancy but for the kakapo, it basically means he turns his tail with his wings spread, then walks backwards towards the female. Weird dance, but the female kakapo thinks it’s cool.

After a female chooses a male, they mate and then the female leaves him and walks home. She builds a nest in a hollow tree or in a hidden crevice among roots or rocks, and lays one to four eggs. She takes care of the eggs and the babies by herself, and may continue to feed the babies until they’re around six months old.

The kakapo eats nuts, seeds, fruit, leaves, and other plant material. Its legs are short but strong, and it will jog for long distances to find food. It can also climb really well, right up into the very tops of trees. It uses its strong legs and its large curved bill to climb. Then, to get down from the treetop more efficiently, the kakapo will spread its wings and parachute down, although its wings aren’t big enough or strong enough for it to actually fly. A big heavy male sort of falls in a controlled plummet while a small female will land more gracefully.

While the kakapo is doing a lot better now than it has in decades, it’s still critically endangered. The current population is 249 individuals according to New Zealand’s Department of Conservation. Scientists and volunteers help monitor the birds, especially newly hatched chicks. If a mother bird is having trouble finding enough food for all her babies, or if any of the babies appear sick or injured, a team of conservationists will decide if they need to help out. They sometimes move a chick from a nest where the mother bird has a lot of other babies to one where there are only one or two babies. Some chicks are raised in nurseries if necessary and reintroduced to the wild when they’re old enough.

The kakapo can live for a long time. This isn’t unusual for parrots, which can live as long as a human, but the kakapo is especially long-lived. There are reports of individuals who have reached 120 years old. This means that potentially, only six kakapo generations ago, the first East Polynesian sailors, ancestors of the modern Maori, became the first humans ever to set foot on the shores of New Zealand. And there were some weird parrots there.

This is what the male kakapo sounds like when it’s booming:

[booming call]

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 304: Animals of the Paleogene

Thanks to Pranav for suggesting this week’s topic, animals of the Paleogene, the period after the Cretaceous! Thanks also to Llewelly for suggesting the horned screamer, now one of my favorite birds.

Further watching:

Southern Screamers making noise

Horned Screamers making noise

Further reading:

The Brontotheres

Presbyornis looked a lot like a long-legged goose [art by Smokeybjb – CC BY-SA 3.0]

The southern screamer (left) and horned screamer (right), probably the closest living relation to Presbyornis:

Megacerops was really really big:

All four of these illustrated animals are actually megacerops, showing the variation across individuals of nose horn size:

Uintatherium had a really weird skull and big fangs:

Pezosiren didn’t look much like its dugong and manatee descendants:

Show transcript:

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

This week we’re going to look at some strange animals of the Paleogene period, a suggestion from Pranav. Pranav also suggested the naked mole-rat that we talked about in episode 301, but I forgot to credit him in that one.

As we talked about in episode 240, about 66 and a half million years ago, a massive asteroid smashed into the earth and caused an extinction event that ended the era of the dinosaurs. The geologic time period immediately after that event is called the Paleogene, and paleontologists study this era to learn how life rebounded after the extinction event. We’re going to learn about a few animals that evolved to fill ecological niches left vacant after dinosaurs went extinct.

These days, mammals fill a whole lot of these ecological niches, so it’s easy to assume that mammals have been successful for the last 66 million years. But while that’s true now, birds were incredibly successful for a long time. Basically for millions of years after the non-avian dinosaurs died out, it was dinosaurs 2.0 as the avian dinosaurs, better known as birds, spread throughout the world and evolved into some amazing organisms.

This included terror birds, which we talked about in episode 202. They lived in South America, except for one species from North America, and evolved really soon after the dinosaurs went extinct, appearing in the fossil record about 60 million years ago. They lasted a long time, too, only going extinct around 2 million years ago.

The earliest known terror bird was about three feet tall, or 91 cm, but its descendants became larger and more fearsome until they were apex predators throughout South America. The biggest species grew up to ten feet tall, or three meters, with a massive beak and sharp claws on its toes. It couldn’t fly but was a fast runner. You would not want a terror bird chasing you.

Lots of other birds evolved throughout the Paleogene, but most of them would look pretty familiar to us today. Paleontologists have found fossils of the ancestors of many modern birds, including penguins, hummingbirds, and parrots, which shows that they were already specialized some 25 or 35 million years ago or even more. In the case of penguins, we have fossils of penguin ancestors dating back to the late Cretaceous, before the extinction event. Those ancient penguins could probably still fly, but it didn’t take too long to evolve to be a fully aquatic bird. The species Waimanu manneringi lived around 62 million years ago in what is now New Zealand. It resembled a loon in a lot of ways, with its legs set well back on its body, and it probably spent much of its time floating on the water between dives. But unlike a loon, it had lost the ability to fly and its wings were already well adapted to act as flippers underwater.

Another bird would have looked familiar at first glance, but really weird when you gave it a second look. Presbyornis lived between about 62 and 55 million years ago in what is now North America, and it lived in flocks around shallow lakes. It was the size of a swan or goose and mostly shaped like a goose, with a fairly chonky body and a long neck. It had a large, broad duckbill that it used to filter small animals and plant material from the water and its feet were webbed…but its legs were really long, more like a heron’s legs.

When the first Presbyornis fossils were found in the 1920s, the scientists thought they’d found ancient flamingos. But when a skull turned up, Presbyornis was classified with ducks and geese. It wasn’t very closely related to modern ducks and geese, though. Researchers now think its closest modern relation is a South American bird called the screamer. Llewelly suggested the horned screamer a long time ago and now that I have learned more about these birds, I love them so much!

The screamer looks sort of like a goose but has long, strong legs and a sharp bill more like a chicken’s. It lives in marshy areas and eats pretty much anything, although it prefers plant material. It has two curved spurs that grow on its wings that it uses to defend its territory from predators or other screamers, and if a spur breaks off, which it does pretty often, it grows back. The screamer mates for life and both parents build the nest together and help take care of the eggs and chicks when they hatch.

The horned screamer has a long, thin structure that grows from its forehead and looks sort of like a horn, although it’s not a horn. It’s wobbly, for one thing, but it’s also not a wattle. It grows throughout the bird’s life and may break off at the end every so often, and it’s basically unlike anything seen in any other bird. Maybe presbyornis had something similar, who knows?

The screamer gets its name from its habit of screaming if it feels threatened or if it just encounters something new or that it doesn’t like. The screaming is actually more of a honking call that sounds like this:

[screamer call]

People sometimes raise screamers with chickens to act as guard birds. It can run fast but it can swim faster, and it can also fly although it doesn’t do so very often. Although it’s distantly related to ducks, its meat is spongy and full of air sacs that help keep it afloat in the water, so people don’t eat it. It is vulnerable to habitat loss, though.

One organism that evolved early in the Paleogene was grass. You know, the plant that a whole lot of animals eat. There are lots and lots of different types of grass, not just the kind we’re used to mowing, and as the Paleogene progressed, it became more and more widespread. But it wasn’t as ubiquitous as it is now, so even though the ancestors of modern grazing animals evolved around the same time, they weren’t grazers yet. The word graze comes from the word grass, but ancient ancestors of horses and other grazing animals were still browsers. They ate all kinds of plants, and didn’t specialize as grazers until grasses really took off and huge grasslands developed in many parts of the world, around 34 million years ago.

Because the Paleogene lasted so long, between about 66 and 23 million years ago, there’s literally no way we can talk about more than a few animals that lived during that time, not in a single 15-minute episode. We’ve also covered a lot of Paleogene animals in previous episodes, like paraceratherium in episode 50, the largest land mammal known. It probably grew up to about 16 feet tall at the shoulder, or 5 meters, and taller if you measured it at the top of its head. Other examples are moeritherium, an ancient elephant relation we talked about in episode 18, the giant ground sloth that we talked about in episode 22, and the ancient whale relation basilosaurus that we talked about in episode 132. Patrons also got a bonus basilosaurid episode this month. But I’m pretty sure we’ve never talked about brontotheres.

Brontotheres first appear in the fossil record around 56 million years ago and they lived until at least 34 million years ago. All animals in the family Brontotheriidae are extinct, but they were closely related to horses. They didn’t look like horses, though; they looked a lot like weird rhinoceroses, although remember that rhinos are also related to horses. They were members of the odd-toed ungulates, along with tapirs and the gigantic Paraceratherium.

Fossil remains of brontotheres have been found in North America, a few parts of eastern Europe, and Asia, although they might have been even more widespread. The earliest species were only about three and a half feet tall at the shoulder, or about a meter, but later species were much larger. While they looked a lot like rhinos, they didn’t have the kind of keratin hose horns that rhinos have. Instead, some species had a pair of horns made of bone that varied in shape and size depending on species. The horns were on the nose as in rhinos, but were side-by-side.

Brontotheres developed before grasslands became widespread, and instead they were browsers that mostly ate relatively soft vegetation like leaves and fruit. Grass is really tough and animals had to evolve specifically to be able to chew and digest it. In fact, the rise of grasslands as the climate became overall much drier around 34 million years ago is probably what drove the brontotheres to extinction. They lived in semi-tropical forests and probably occupied the same ecological niche that elephants do today. This was before elephants and their relations had evolved to be really big, and brontotheres were the biggest browsing animals of their time.

Brontotheres probably lived in herds or groups of some kind. They were widespread and common enough that they left lots of fossils, so many that they were found relatively often in North America even before people knew what fossils were. The Sioux Nation people were familiar with the bones and called them thunder horses. When they were scientifically described in 1873 by Othniel Marsh, he named them after the Sioux term, since brontotherium means “thunder beast.”

Two of the biggest brontotheres lived at about the same time as each other, around 37 to 34 million years ago. Megacerops lived in North America while Embolotherium lived in Asia, specifically in what is now Mongolia. Megacerops is the same animal that’s sometimes called brontotherium or titanotherium in older articles and books.

Megacerops and Embolotherium were about the same size, and they were huge, although Embolotherium was probably just a bit larger than Megacerops. They stood over 8 feet tall at the shoulder, or 2.5 meters, and were more than 15 feet long, or 4.6 meters. This is much larger than any rhinos alive today and as big as some elephants. Their legs would probably have looked more like an elephant’s legs than a rhinoceros’s.

Brontothere nose horns weren’t true horns, since they don’t seem to have been covered with a keratin sheath, but they were formed from protrusions of the nasal bones. They might have been more like ossicones, covered with skin and hair. Megacerops had a pair of nose horns that were much larger in some individuals than others, and scientists hypothesize that males had the larger horns and used them to fight each other.

But this can’t have been the case for embolotherium. It had even bigger nose horns that were fused together in a wedge-shaped plate sometimes referred to as a ram, but they contained empty chambers inside that were a continuation of the nasal cavities. They wouldn’t have been strong enough to bash other embolotheriums with, but they might have acted as resonating chambers, allowing embolotherium to communicate with loud sounds. All individuals had these nose horns, even juveniles, and they were all about the same size, which further suggests that they had a purpose unrelated to fighting.

At about the same time the brontotheres were evolving, another big browsing animal also lived in what are now China and the United States. Two species are known, one in each country, and both stood about 5 feet tall at the shoulder, or 1.5 meters. It looked sort of like a brontothere in some ways, but very different in other ways, especially its weird skull, and anyway it was already big around 56 million years ago when brontotheres were still small and unspecialized.

Scientists aren’t sure what uintatherium was related to. It’s been placed in its own genus, family, and order, although some other uintatherium relations have been discovered that share its weird traits. Most scientists these days think it was probably an ungulate.

Uintatherium’s skull was extremely strong and thick, which didn’t leave a whole lot of room for brains. But what uintatherium lacked in brainpower, it made up for in sheer defensive ability. It had huge canine teeth that hung down like a sabertooth cat’s fangs, although males had larger fangs than females. Males also had three pairs of ossicones or horns on the top of the skull that pointed upwards. One pair was on the nose, one pair over the eyes, and one pair almost on the back of the skull. They could be as much as 10 inches long, or 25 cm, and paleontologists think that males wrestled with these horns the same way male deer will lock antlers and wrestle.

Uintatherium lived in the same habitat and probably ate more or less the same type of plants that later brontotheres did. They went extinct around the time that brontotheres evolved to be much larger, which suggests that brontotheres may have outcompeted uintatherium.

We’ll finish with one more Paleogene mammal, Pezosiren. It was only described in 2001 from several incomplete specimens discovered in Jamaica in the 1990s, and it lived between 49 and 46 million years ago.

Pezosiren was about the size of a pig, although it had a longer, thicker tail compared to pigs. It wasn’t any kind of pig, though, and in fact it was distantly related to elephants. It was the oldest known ancestor of modern sirenians. Pezosiren is also called the walking siren, because it still had four legs and probably spent at least part of the time on land, although it could swim well. Scientists think it probably swam more like an otter than a sirenian, propelling itself through the water with its hind legs instead of its tail.

Pezosiren was probably semi-aquatic, sort of like modern hippos, and already shows some details specific to sirenians, especially its heavy ribs that would help it stay submerged when it wanted to. It ate water plants and probably stayed in shallow coastal water. At different times in the past, Jamaica was connected to the North American mainland or was an island on its own as it is now, or occasionally it was completely submerged. About 46 million years ago it submerged as sea levels rose, and that was the end of Pezosiren as far as we know. But obviously Pezosiren either survived in other areas or had already given rise to an even more aquatic sirenian ancestor, because while Pezosiren is the only sirenian known that could walk, its descendants were well adapted to the water. They survive today as dugongs and manatees.

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