Monthly Archives: December 2017

Episode 047: Strange Horses

It’s the last episode of 2017 and we’re going out in style, learning about some unusual horses!

A Przewalski’s horse PHOTO TAKEN BY ME AT HELSINKI ZOO I cropped out as many poops as I could:

A Heck horse, also sometimes called a tarpan. Photo taken by *squints* Klaus Rudloff in Berlin:

A Moyle breed horse with a bossed forehead:

Show transcript:

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

This week we’re going to learn about an animal I’ve been bonkers crazy about since I was a kid, the horse. But not just regular horses. We’re going to learn about some strange and little-known horses, the best kind of all.

All domestic horses are the same subspecies, Equus ferus caballus, even though the various breeds may look very different. Even mustangs and other populations of wild horses—more properly called feral horses—are the same subspecies. Feral just means a domestic animal that lives like a wild animal, like a stray dog. Only one truly wild horse remains these days, Przewalski’s [pzha-VALski’s] horse, Equus ferus przewalskii. I’ve been pronouncing it Perzwalski’s horse my whole life until today. So let’s start the episode by talking about that one.

Przewalski’s horse is native to the steppes of central Asia, especially Mongolia. It’s currently considered a subspecies of horse, but some researchers think it should be its own species. It went extinct in the wild in 1969. Fortunately, in 1900 15 of the horses had been captured and sold to various zoos. Some of the pairs reproduced, but by 1945, only 13 of the descendants remained. Of those 13, two were hybrids, one of them with a domestic horse, one of them with a tarpan. More about tarpans in a minute. Nine of the 13 were used in a careful breeding program, which was so successful that by 1992, Przewalski’s horse started to be reintroduced to the wild.

I’ve seen Przewalski’s horses, by the way. They had some in the Helsinki Zoo. Check the show notes for a picture taken by me and not swiped by me off the internet.

Przewalski’s horse is stockier than domestic horses, dun in color with a pale belly, with a short, erect mane. The legs are frequently faintly striped. The average horse stands about 13 hands high at the withers, which is the shoulder hump, or four feet four inches, or 132 cm. Its social structure is pretty much the same as the domestic horse’s. It lives in bands consisting of a group of mares and their young, and a stallion that leads the band to grazing areas and water while keeping watch for danger. A solitary stallion may sometimes challenge a stallion with a band of mares, which leads to a fight, which is pretty much the basis of 80% of the horse stories I read as a kid. So exciting.

So what about the tarpan? It was also called the Eurasian wild horse, and it went extinct—for good, unfortunately—in 1918 at the very latest, but probably much earlier. Its scientific name is Equus ferus ferus, and it’s probably the wild horse that gave rise to the modern domesticated horse. But we don’t know for sure, because we don’t know for sure that the tarpans alive in the 18th and 19th centuries were even real tarpans. They might have been hybrids of local domestic horses and Przewalski’s horses, or just feral domestic horses.

We do know that wild horses lived throughout Europe and parts of Asia during the Pleistocene. We have cave paintings 30,000 years old that are so good, scientists can determine a lot about the wild horse’s conformation and coat patterns and colors. We know our ancestors killed and ate horses long before anyone realized how useful it would be to tame such a strong animal and let it do the hard tasks of pulling carts and plows. The horse was domesticated about 6,000 years ago in various places at different times across Eurasia, and it’s possible that different subspecies of horse were domesticated, of which the tarpan was one. But we’re not sure how many subspecies of wild horse there were. We know about Przewalski’s horse since it’s still around, and we know a fair bit about the tarpan because it survived well into modern times. There were probably others, including what might be a type of tarpan that lived in forests.

There’s an interesting etymological fact that might point to the forest tarpan as a distinct type of wild horse. This comes from Willy Ley’s marvelous book, The Lungfish, the Dodo, and the Unicorn, which I’ve read numerous times since I was a kid. A lot of the information is dated since it was first published in the 1940s, but it was cutting edge at the time. Also, the book was already old when I was a kid. I’m not that old. Anyway, Ley writes that there was an unusual Bavarian insult used when someone in southern Germany wanted to call someone else stupid. In other parts of German-speaking Europe, a stupid person is called an Esel, or donkey. But the Bavarian term is Waldesel, which means forest donkey. Ordinary donkeys are called Steinesel, or rock donkey. So some researchers think, or thought 80 years ago, that the Waldesel referred to the forest tarpan. It was supposed to be gray with a black stripe down the spine called an eel stripe, and like other wild horses had a big, donkey-like head.

At some point, when horses were fully domesticated, the wild horses became a pest. They stole domestic mares and ate fodder meant for livestock. So not only were they hunted for meat, they were killed just to get rid of them. By the late 19th century, tarpans were already rare, whether they were really wild horses or hybrids of wild and domestic horses. The last one was killed in the wild in 1879 or the first few days of 1880, the last one in captivity died in the early 20th century—reports vary as to whether it was in 1909, 1917, or 1918, and there are some doubts that these last horses were actually tarpans.

The tarpan looked a lot like Przewalski’s horse: small, stocky, and with a large head, with short mane and tail. They were mostly bay in color—that’s brown with black mane and tail—but dun, black, gray, and other shades were also present. Unlike Przewalski’s horse, the mane fell across the neck like the domestic horse, but was shorter.

So is the tarpan really extinct? If you go online you can find tarpans for sale. What’s up with that?

As early as 1780, people realized the tarpan needed help to survive. That’s when the Polish government established a wildlife park to protect the tarpans living there, but it closed in 1806 and the horses were given to local farmers. A small number of tarpans were kept in zoos. In the 1930s and after, people have tried to breed a horse that closely resembles the tarpan, starting with domestic stock that probably have recent tarpan ancestors. Various breeds of horse have resulted, notably the Heck horse, often called a tarpan. It isn’t really a tarpan, but it sure is beautiful.

There are many horses in folklore, from Pegasus to the kelpie, centaurs to unicorns, but very few actual mystery horses. I looked, believe me. The kelpie, if you’re unfamiliar with the term, is a Scottish water spirit that sometimes appears as a pony with a sopping wet mane. Don’t try to catch it. The second you touch it, it’ll drag you into the water and drown you.

Anyway, I dug around and found not a mystery horse, but something really interesting about horses with horns—not like a unicorn’s horn, but something even stranger. Something real.

Every so often there are reports of a horse with a pair of horns on the forehead. Sometimes they’re described as tiny, although older accounts are more sensational. For instance, an 1837 account from a South American explorer talks about a horse with four-inch long horns like a bull’s, and another with horns three inches long. That would be about 8 cm to 10 cm.

Well, there are a few breeds of horse with what are called bossed foreheads. Basically this means the forehead sometimes has a pair of bony bulges or points above the eyes or near the ears that do look like tiny fur-covered horns like those seen in giraffes, or horn buds where horns could grow. Sometimes a horse will have only one of the bumps, but mostly they grow in pairs. Moyle horses, a North American breed, have the bossed forehead, as do the Datong from China and the Carthusian Andalusians. All three of these breeds are rare. Sometimes the trait appears in other breeds.

Now, these are no three- or four-inch horns. They’re just little bumps maybe a centimeter or so long, or about half an inch. It’s also not clear whether they’re real horns or just calcium deposits of some kind, but since they do seem to be situated consistently in spots where horns could reasonably expect to grow, it’s possible they are due to a genetic glitch that fails to fully suppress an ancient gene sequence that once grew horns. The problem is, as far as we know, there are no horse ancestors that ever grew horns.

While warts and bumps are as common in horses as they are in any mammal, this particular kind of horn-like bump doesn’t seem to appear anywhere else on a horse, even on those with bossed foreheads. A bossed forehead is also supposedly linked with high endurance, but as far as I know there are no real studies about the condition. So if you know someone who’s thinking about going into veterinary medicine, zoology, or a related field, suggest bossed foreheads as a particular topic of study. And then tell them to let me know their findings.

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

Thanks for listening!

Episode 046: The Other Loch Ness Monsters

There’s more in Loch Ness than one big mystery animal. This week we look at a few smaller mystery animals lurking in the cold depths of the lake.

Further reading:

Here’s Nessie: A Monstrous Compendium from Loch Ness by Karl P.N. Shuker

The goliath frog:

The Wels catfish (also, River Monsters is the best):

An amphipod:

Show transcript:

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

Back in episode 29, I dismissed Nessie, the Loch Ness monster, as probably not a real animal. But this week we’re heading back to Loch Ness to see what other monsters might lurk in its murky depths.

WHAAAAA? Other Loch Ness monsters???

Yes, really! See, ever since the first sightings of Nessie in the 1930s, Loch Ness has been studied and examined so closely that it would be more surprising if no one had ever spotted other mystery animals.

The source of most of the information in this episode is from zoologist Karl Shuker’s book Here’s Nessie! A Monstrous Compendium from Loch Ness. Check the show notes for a link if you’re interested in buying your own copy of the book.

Our first non-Nessie mystery dates from 1934, but it happened, supposedly, sometime in the 1880s. It appeared in the Northern Chronicle, an Inverness newspaper, on January 31, 1934. The article relates that a ship in Loch Ness hit a submerged reef called Johnnie’s Point and sank one night. Luckily no one died. The next day a local diving expert named Duncan Macdonald was hired to determine if the wreck could be raised, but he couldn’t spot the wreck during his dive.

Later that evening, some of the ship’s crew who had heard stories about strange creatures living in Loch Ness asked Macdonald whether he’d seen anything unusual. After some urging, Macdonald finally admitted that he had seen a frog-like creature the size of a good-sized goat sitting on a rock ledge some 30 feet, or 9 meters, underwater. It didn’t bother him so he didn’t bother it.

There are a lot of problems with this account, of course. For one thing, we don’t know who wrote it—the article has no byline. It’s also a secondhand account. In fact, the article ends with this line: quote “The story, exactly as given, was told by Mr Donald Fraser, lock-keeper, Fort Augustus, who often heard the diver (his own grand-uncle) tell it many years ago.” unquote

Plus, of course, frogs don’t grow as big as goats. The biggest frog is the goliath frog, which can grow over a foot, or 32 cm, in length nose to tail, or butt I guess since frogs don’t have tails, which is pretty darn big but not anywhere near as big as a goat. The goliath frog also only lives in fast-moving rivers in a few small parts of Africa, not cold, murky lakes in Scotland, and its tadpoles only feed one one type of plant. In other words, even if someone did release a goliath frog into Loch Ness in the 1880s—which is pretty farfetched—it wouldn’t have survived for long.

The biggest frog that ever lived, as far as we know, lived about 65 million years ago and wasn’t all that much bigger than the goliath frog, only 16 inches long, or 41 cm. It had little horns above its eyes, which gives it its name, devil frog. Its descendants, South American horned frogs, also have little horns but are much smaller.

So what might Mr. Macdonald have seen, assuming he didn’t just make it all up? Some species of catfish can grow really big, but catfish aren’t native to Scotland. It’s always possible that a few Wels catfish, native to parts of Europe, were introduced into Loch Ness as a sport fish but didn’t survive long enough to establish a breeding population in the cold waters. Catfish have wide mouths, although their eyes are small, and might be mistaken for a frog if seen head-on in poor light. Plus, the Wels catfish can grow to 16 feet long, or 5 meters.

Then again, since the article was published during the height of the first Loch Ness monster frenzy, it might all have been fabricated from beginning to end.

A 1972 search for Nessie by the same team that announced that famous underwater photograph of a flipper, which later turned out to be mostly painted on, filmed something in the loch that wasn’t just paint. They were small, pale blobs on the grainy film. The team called them bumblebees from their shape.

Then in July of 1981, a different company searching not for Nessie but for a shipwreck from 1952 filmed some strange white creatures at the bottom of the loch. One of the searchers described them as giant white tadpoles, two or three inches long, or about 5 to 7 cm. Another searcher described them as resembling white mice but moving jerkily.

The search for the wreck lasted three weeks and the white mystery animals were spotted more than once, but not frequently. Afterwards, the company sent video of them to Dr. P Humphrey Greenwood, an ichthyologist at the Natural History Museum in London. Since this was the 1980s, of course, the film was videotape, not digital, but Dr. Greenwood got some of the frames computer enhanced. Probably on a computer that had less actual computing power than my phone. Anyway, the enhancement showed that the animals seemed to have three pairs of limbs. Dr. Greenwood tentatively identified them as bottom-dwelling crustaceans, but not ones native to Loch Ness.

Over the years many people have made suggestions as to what these mystery crustaceans might be. I’m going out on a limb here and declaring that they are not baby Loch Ness monsters. Karl Shuker suggests the white mice footage, at least, might be some kind of amphipod.

We’ve met amphipods before in a couple of episodes, mostly because some species exhibit deep-sea gigantism. Amphipods are shrimp-like crustaceans that live throughout the world in both the ocean and fresh water, and most species are quite small. While they do have more than three pairs of legs—eight pairs, in fact, plus two pairs of antennae—the 1981 videotape wasn’t of high quality and details might easily have been lost. Some of the almost 10,000 known species of amphipod are white or pale in color and grow to the right size to be the ones filmed in Loch Ness. But no amphipods of that description have ever been caught in Loch Ness.

New amphipods are discovered all the time, of course. They’re simply everywhere, and the smallest species are only a millimeter long. But because they’re so common, it’s also easy to transport them from one body of water to another. A rare amphipod discovered in Alpine lakes only a few years ago is already threatened by a different, more common species of amphipod introduced to one of the lakes by accident. So it’s possible that the white mice crustaceans in Loch Ness traveled there on someone’s boat.

That’s certainly the case with another creature found in Loch Ness in 1981, but we know exactly what this one is. It’s a flatworm native to North America, a bit over an inch long, or 3 cm, and only about 5 millimeters wide. It attaches its cocoons to boat bottoms, and in this case it was brought to Loch Ness by equipment used to hunt for Nessie. Spoiler alert: they didn’t find her.

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

Thanks for listening!

Episode 045: Monotremes

At last, it’s the episode about the platypus, a monotreme! Only two kinds of monotremes remain: the platypus and the echidna. Monotremes are mammals that lay eggs! Not even making that up.

The echidna:

Do not eat:

A platypus and another platypus:

Show transcript:

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

This week we’re finally, finally going to look at the platypus and its relations, called monotremes. I’ve been promising a platypus episode for months and now, it is time.

There is so much weird about the platypus, it’s hard to know where to start. So let’s pull back for a second and look at the bigger picture.

Hopefully most of my listeners are familiar with what traits make an animal a mammal instead of a bird or a fish or what have you. At some point in elementary school, you either had to memorize a list of mammalian traits or you will have to memorize one. The list will be something like this: mammals are warm-blooded, grow hair, and feed their babies with milk. Boom, that’s a mammal. There are more differences than that, and some minor exceptions in the growing hair category, but those are the big differences. But even a little tiny baby who doesn’t know anything knows the difference between a bird and, say, a cat or dog. Birds have feathers, mammals never do. Birds lay eggs, mammals never do.

But wait. That’s wrong. Not the feather thing, but the egg-laying. Some mammals lay eggs. Specifically, the monotremes.

There are three main types of mammals. The biggest is the placental mammal group, which includes humans, dogs, cats, mice, bats, horses, whales, giraffes, and so on. A female placental mammal grows her babies inside her body in the uterus, each baby wrapped in a fluid-filled sac called a placenta. During birth, the placenta tears open and the baby is born first, followed by the placenta, which is frequently called the afterbirth. Placental mammals are pretty well developed when they’re born, with considerable variation. Baby deer and horses, for instance, can stand and run within a few hours of birth, while kittens and puppies don’t even have their eyes open yet. But they’re all mostly done cooking, so to speak.

The second type is the marsupial mammal group, which includes possums, kangaroos, koalas, wombats, sugar gliders, and so on. A female marsupial has two uteruses, and while her babies initially grow inside her, they’re born very early. A baby marsupial, called a joey, is just a tiny little pink squidge about the size of a bean that’s not anywhere near done growing, but it’s not completely helpless. It has relatively well developed forelegs so it can crawl up its mother’s fur and find a teat. Some species of marsupial have a pouch around the teats, like possums and kangaroos, but other species don’t. Either way, once the baby finds a teat, it clamps on and stays there for weeks or months while it continues to grow.

The third and rarest type of mammal is the monotreme group, and monotremes lay eggs. But their eggs aren’t like bird eggs. They’re more like reptile eggs, with a soft, leathery shell. The female monotreme keeps her eggs inside her body until it’s almost time for them to hatch. The babies are small squidge beans like marsupial newborns, and I’m delighted to report that they’re called puggles. Echidnas have pouches and after a mother echidna lays her single egg, she tucks it in the pouch. The platypus doesn’t have a pouch, so after she lays her one to three eggs, a mother platypus holds them against her belly with her flat tail to keep them warm.

Monotremes show a number of physical traits that are considered primitive. Some of the traits, like the bones that make up their shoulders and the placement of their legs, are shared with reptiles but not found in most modern mammals. Other traits are shared with birds. The word monotreme means “one opening,” and that opening, called a cloaca, is used for reproductive and excretory systems instead of those systems using separate openings.

It wasn’t until 1824 that scientists figured out that monotreme moms produce milk. They don’t have teats, so the puggles lick the milk up from what are known as milk patches. Before then a lot of scientists argued that monotremes weren’t mammals at all and should either be classified with the reptiles or as their own class, the prototheria.

It’s easy to think, “Oh, that mammal is so primitive, it must not have evolved much since the common ancestor of mammals, birds, and reptiles was alive 315 million years ago,” but of course that’s not the case. It’s just that the monotremes that survived did just fine with the basic structures they evolved a long time ago. There were no evolutionary pressures to develop different shoulder bones or stop laying eggs. Other structures have evolved considerably.

There are only two types of monotremes still living today, the platypus and the echidna, also called the spiny anteater. We only have one species of platypus but four species of echidnas. All monotremes live in Australia and New Guinea these days, but once they were common throughout much of the world. The oldest platypus fossil found is from South America. But around 60 or 70 million years ago, the ancestors of today’s marsupials started to outcompete the monotremes. Researchers think the ancestor of the platypus and echidna survived because it spent a good part of its life in water. Marsupials are not water animals because their joeys will drown.

Let’s talk about the echidna first. The echidna is a land animal, unlike its ancestors, although it swims well and likes water. It looks a lot like a big hedgehog with a long nose. It’s around a foot to 18 inches long, or 30 to 45 cm. Its short fur is brown or black in color with paler spines, and like a hedgehog it will curl up when threatened so that its spines stick out. It has short, powerful legs that it uses to dig burrows and dig up insects, worms, and especially termites, which it slurps up with a sticky tongue. It doesn’t have teeth. It lives in forests and is a solitary animal most of the time.

Now, the platypus. When I was a kid, pretty much all my knowledge of the platypus, and Australia in general, came from the cartoon Dot and the Kangaroo, so I’m upset to report that the scientific name of the platypus has been changed from Ornithorhynchus paradoxis to Ornithorhynchus anatinus. Sometimes people say duck-billed platypus, which isn’t wrong but since there’s only one species of platypus there’s no reason to be that specific, guys. The snout looks like a duck bill but it’s actually very different. It’s soft and rubbery and it’s packed with electroreceptors that allow the platypus to sense the tiny electrical fields generated by muscular contractions in its prey.

When the first platypus skin was brought to Europe in 1798, scientists immediately decided it was a big fakey fake. Obviously some wag had taken a dead beaver and stuck a duck’s bill on it. It wasn’t until 1802 that a scientist was able to dissect a recently killed platypus and realized that not only was it a real animal, not a hoax, but it was really weird. And they didn’t even know until 1884 that it laid eggs.

The platypus is about 20 inches long, or 50 cm, and it has brown fur that’s short and very dense. The platypus spends a lot of time in the water, and its fur traps air close to the skin to help keep the animal warm while not allowing water in. It has a strong flattened tail that acts as a rudder when it swims, along with its hind feet. It actually swims using its big webbed forefeet. It lives in eastern Australia along rivers and streams, and digs a short burrow in the riverbank to sleep in. The female digs a deeper burrow before she has her babies, sometimes over 65 feet long, or 20 meters. At the end she makes a nest out of leaves.

The platypus eats pretty much everything it can catch, from worms and fish to crustaceans and insects. Platypus puggles are born with a few teeth, but lose them as they grow up. Adults don’t have teeth at all, just hardened skin. While it’s underwater, the platypus closes its eyes, nostrils, and ears, and instead navigates and hunts by means of its well-developed electrolocation abilities. The echidna has some electroreceptors but only a fraction of the number the platypus has. Males of both the echidna and the platypus have sharp spurs on their hind legs, but only the platypus can inject venom. Researchers still aren’t sure why.

The platypus is difficult to keep in captivity, so unless you visit Australia you probably won’t get to see one. The echidna is less difficult to keep in captivity but won’t breed in captivity. So if you live in the same parts of the world where the last living monotremes live, consider yourself lucky because you might catch a glimpse of the only mammals that still lay eggs.

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

Thanks for listening!

Episode 044: Extinct and Back from the Brink

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

The passenger pigeon (stuffed):

The tiny black robin. It fights crime!

The Tecopa Pupfish is not happy about being extinct:

The West Virginia Northern Flying Squirrel SO CUTE:

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

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

The Organization for Bat Conservation

Episode transcript:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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Thanks for listening!