Episode 368: The Bison

Thanks to Jason for suggesting this week’s topic, the bison!

Further reading:

New research documents domestic cattle genetics in modern bison herds

Higgs Bison: Mysterious Hybrid of Bison and Cattle Hidden in Ice Age Cave Art

A cave painting of steppe bison and other animals:

An American bison [photo by Kim Acker, taken from this site]:

Some European bison [photo by Pryndak Vasyl, taken from this site]:

The bison sound in this episode came from this site.

Show transcript:

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

This week we’re going to learn about the bison, a suggestion from Jason. There are two species of bison alive today, the American bison and the European bison. Both are sometimes called buffalo while the European bison is sometimes called the wisent. I’m mostly going to call it the wisent too in this episode so I only have to say the word bison 5,000 times instead of 10,000.

Bison are herd animals that can congregate in huge numbers, but these big herds are made up of numerous smaller groups. The smaller groups are made up of a lead female, called a cow, who is usually older, other cows, and all their offspring, called calves. Males, called bulls, live in small bachelor groups. The American bison mostly eats grass while the European bison eats a wider selection of plants in addition to grass.

The bison is a big animal with horns, a shaggy dark brown coat, and a humped shoulder. The American bison’s shoulder is especially humped, which allows for the attachment of strong neck muscles. This allows the animal to clear snow from the ground by swinging its head side to side. The European bison’s hump isn’t as pronounced and it carries its head higher. The bison looks slow and clumsy, but it can actually run up to 35 mph, or 55 km/hour, can swim well, and can jump obstacles that are 5 feet tall, or 1.5 meters.

The American bison can stand over six and a half feet high at the shoulder, or 2 meters, while the European bison stands almost 7 feet tall at the shoulder, or 2.1 meters. This is massively huge! Bison are definitely ice age megafauna that once lived alongside mammoths and woolly rhinos, so we’re lucky they’re still around. Both species almost went extinct in recent times and were only saved by a coordinated effort by early conservationists.

The American bison in particular has a sad story. Before European colonizers arrived, bison were widespread throughout North America. Bison live in herds that migrate sometimes long distances to find food, and many of the North American tribes were also migratory to follow the herds, because the bison was an important part of their diet and they also used its hide and other body parts to make items they needed. The colonizers knew that, and they knew that by killing off the bison, the people who depended on bison to live would starve to death. Since bison were also considered sacred, the emotional and societal impact of colonizers killing the animals was also considerable.

In the 19th century, colonizers killed an estimated 50 million bison. A lot of them weren’t even used for anything. People would shoot as many bison as possible from trains and just leave the bodies to rot, and this practice was actually encouraged by the railroads, who advertised these “hunting” trips. The United States government also encouraged the mass killing of bison and even had soldiers go out to kill as many bison as possible. Bison that escaped the coordinated slaughter often caught diseases spread by domestic cattle, and the increased plowing and fencing of prairie land reduced the food available to bison. By 1900, the number of American bison in the world was probably only about 300.

As early as the 1860s people started to sound the alarm about the bison’s impending extinction. Some ranchers kept bison, partly as meat animals and partly to just help stop them from all dying out. The Yellowstone National Park had been established in 1872, and 25 bison survived there, although many others were poached by hunters. Members of various Plains tribes, who had been forced onto reservations by the United States government so the government could give their land to colonizers, collected as many bison as they could to keep them safe.

These days the American bison is out of immediate danger, although its numbers are still very low. Because there were so few bison when conservation efforts started, the genetic diversity is also low. Bison will also hybridize with domestic cattle and the resulting female calves are fertile, so the main goal of modern conservationists is to genetically test herds to determine which bison have a larger percentage of cattle genes, and mainly only breed the ones that have the least. A 2022 study determined that there is no population of American bison alive today that doesn’t have at least a small percentage of cattle genes. Cattle are domesticated animals, and it’s never a good thing when a wild animal ends up with the DNA of a domestic counterpart. Bison need their wildness in order to survive and stay safe.

There are two living subspecies of American bison, the wood bison and the plains bison. I’m happy to report that the scientific name of the plains bison is Bison bison bison. The wood bison mainly lives in Canada, where it’s classified as threatened.

As for the European bison, or wisent, it was once common throughout much of Europe and Asia. As the human population increased after the ice age, the wisent’s numbers decreased until it was mostly restricted to a few areas of Russia, Transylvania, Poland, and Lithuania. Even as early as the 16th century, people were aware it was endangered. Local rulers declared it a protected animal in most of its range.

During World War I, German troops occupying Poland killed hundreds of wisents, and as the troops retreated at the end of the war, they shot as many of the bison as they could find and left them to rot. Only nine individuals remained alive and by 1921 they had died too. By 1927, the very last wisent in the wild was killed by a poacher.

But 12 animals remained, kept in various zoos. In 1923 a preservation society was set up, modeled after the one in the United States that had helped save the American bison from extinction. Poland in particular worked hard to increase the wisent’s numbers and re-introduce it to its forest home, although its efforts were interrupted by World War II. These days the wisent is out of danger of extinction, although like the American bison its numbers are still relatively low.

American and European bison are related and can crossbreed, but they’re not as closely related genetically as was once thought. Genetic studies are ongoing, but it appears that the wisent is most closely related to domestic cattle while the American bison is most closely related to the yak.

We recently talked about the steppe bison in episode 357, which is about mammoth meat. The steppe bison is an ancestor of the American bison and lived throughout Europe and Asia across to North America, during the Pleistocene when Asia and North America were connected by the land bridge Beringia. It only went extinct around 3,000 years ago. It had much larger horns than modern bison, with a horn spread of almost seven feet across, or over 2 meters.

About 17,000 years ago, in a cave in what is now France, an ancient artist picked up a stick of charcoal and made a drawing of a bison alongside many other bison drawings made by many artists over the years. According to a study published in 2016, there are two different types of bison depicted in the cave. One type is the steppe bison, but the other is distinctly different. After a genetics study of bison in Europe, researchers made a surprising discovery. The second type of bison depicted in the cave is actually a hybrid animal. Hybrids come about when two species of closely related animals interbreed. The more closely related the species are, the more likely they are to interbreed where their territories overlap, and the more likely that the offspring will be fertile. This is exactly what happened toward the end of the Pleistocene, when climate change made it harder for the steppe bison to survive. Instead, a hybrid of steppe bison and the aurochs, the wild ancestor of the domestic cow, not only became common throughout much of Europe, eventually the hybrid species was so numerous that it became a distinct species of its own.

This hybrid bison had small horns and a smaller hump than the steppe bison, although it was still a really big animal. Eventually it gave rise to the modern European bison while the steppe bison gave rise to the antique bison, which itself is the direct ancestor of the American bison. So many bison!

This is what a bison sounds like, specifically an American bison recorded in Yellowstone National Park:

[bison sound]

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 367: The Marozi

Thanks to Pranav for suggesting this mystery big cat this week, the marozi!

Further reading:

From Black Lions to Living Sabre-Tooths: My Top Ten Mystery Cats

Spotted Lions

A young lioness who still has some of her cub spots:

Subadult lions who still have a lot of cub spots:

The skin of an animal supposedly killed in 1931 and said to be a marozi:

Two photos of a “leopon,” a lion-leopard hybrid bred in captivity in a Japanese zoo:

Show transcript:

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

This week we’re going to learn about a mystery animal suggested by Pranav. It’s the marozi, a big cat from the mountains of Kenya.

Kenya is in east Africa, and humans have lived in what is now Kenya since humans existed. Because of this, usually when we talk about Kenya or east Africa, we’re talking about hominins, but today we’re talking about big cats.

Kenya is home to a lot of animals you think of when someone mentions the animals of Africa, like elephants and giraffes, and it’s also home to three big cats: lions, leopards, and cheetahs. The lion is generally a tawny brown color although different individuals and populations can be various shades of brown or gray. A lion cub is born with dark spots, and as it grows the spots fade. Sometimes a young adult lion will still have some spots, especially on its legs and belly, but in general an adult lion has no spots at all. In comparison, both the leopard and the cheetah are famous for their spots.

The lion prefers to live in savannas and open woodlands. These days it’s only found in a few parts of India, along with various places in sub-Saharan Africa. This just means south of the Sahara desert. In the past, though, the lion had a much larger range. It lived throughout most of Africa, the Middle East, southern Asia, and even southern Europe. Overhunting drove it to extinction in many parts of its historic range, which is called extirpation. I’ve used the term before but it specifically means that an animal has been driven to extinction in one area where it once lived, but it isn’t extinct in other areas. Some subspecies of lion have gone extinct, and the lions who remain are vulnerable to habitat loss, poaching, and many other factors. Just because lions are common in zoos doesn’t mean lions in the wild are doing fine.

The same is true of the cheetah, which has an even smaller range than the lion these days but which was once common throughout Africa and the Middle East along with a lot of southern Asia and Europe. We talked about the cheetah in episode 145. It’s actually not closely related to the lion or the leopard, and in fact genetic testing reveals that it’s most closely related to the puma of North America.

The leopard, on the other hand, is a very close relation to the lion. Both belong to the same genus, Panthera, which also includes tigers, jaguars, and snow leopards, but the lion and leopard are the closest cousins. While it’s also vulnerable to habitat loss, poaching, and other factors, it’s more widespread than the lion and cheetah. It lives throughout much of sub-Saharan Africa, Asia–especially India–and even parts of eastern Russia, and in the past it was even more widespread. It prefers forests where its spots help it blend in with dappled sun and shade.

So, the lion, the leopard, and the cheetah all live in Kenya, but there’s another big cat that’s supposed to live there too. It’s called the marozi, also sometimes called the spotted lion.

Stories of lions that have spots like a leopard go back for centuries among the local people. The spotted lion is supposed to be small and the male either has no mane or only a small one. It’s supposed to live in the mountains and is solitary instead of living in family groups like ordinary lions. In fact, “marozi” supposedly means “solitary lion” in the local language. Instead of living in open grasslands, it lives in thick forest where a spotted coat and smaller body size would be useful, allowing it to maneuver through the trees more easily while not being seen.

It wasn’t until the colonial era in the late 19th and early 20th centuries that Europeans became aware of the marozi. The first known sighting of a spotted lion by a European occurred in 1903, when a British soldier reported seeing more than one in the mountains of Kenya. He said the lions were darker in color than an ordinary lion, with leopard-like rosette markings. In 1924, a game warden reported killing a spotted lioness and her cubs, with the lioness having just as many spots as the babies.

In 1931 a farmer shot two small spotted lions in the mountains. He said they were fully grown despite their small size, but they had even more spots than lion cubs do. One was a male and he had a sparse, short mane. The farmer kept the male’s skin, which eventually made its way to the Natural History Museum in London, possibly with the lion’s skull too, although it’s not clear if the skull actually belongs to the same animal. As far as I could find out, no one has tried to test the skin and skull genetically.

Other people, including hunters and game wardens, reported seeing spotted lions in high elevations where ordinary lions didn’t live, with stories continuing through at least the 1960s. Similar stories of a spotted lion have been collected from mountains in other parts of east and central Africa, including Ethiopia, Rwanda, Uganda, and Cameroon, where it has different local names. But so far we don’t have any photographs or a specimen.

There are a few hypotheses about what the marozi might be. One suggestion is that it’s actually a hybrid of a leopard and a lion. Because leopards and lions are so closely related, they can interbreed and produce offspring, although as far as we know this has only happened in captivity. In the wild, lions are actually aggressive towards leopards. A lion will steal a leopard’s food and will sometimes even kill leopards, and as a result leopards try to avoid lions. Since leopards prefer thick forest and lions prefer open forest or grasslands, they don’t cross paths all that often anyway.

In the late 1950s into the early 1960s, a zoo in Japan kept a male leopard and a female lion in the same enclosure to see if they would mate. They did, and eventually they had two litters together. The cubs were larger and heavier than leopards but not as big as lions, and while they generally looked like lions they had leopard spots. The males had small manes.

This sounds a lot like reports of the marozi, but again, in the wild lions and leopards mostly avoid each other. The only time a lion and a leopard would consider each other potential mates instead of potential trouble is when they’re put together artificially as in the Japanese zoo. Even if an occasional leopard and lion do sometimes breed in the wild, it wouldn’t happen often enough to cause all the sightings documented about the marozi. Besides, the marozi is only reported from the mountains, where lions don’t live.

Another hypothesis is that there’s a population of ordinary lions that have moved into the mountains to escape factors like habitat loss, poaching, and a decline in prey animals, and that people occasionally see a young adult lion that hasn’t completely lost its cub spots. This isn’t too likely either since stories of the marozi go back to long before these modern pressures on lion populations.

There might very well be an unknown, very rare species or subspecies of lion that has always lived in the mountains in parts of east and central Africa, and that it does actually have spots as an adult. If this is the case, hopefully it’s safe in its mountain habitat from the pressures faced by ordinary lions. Let’s hope also that it comes to the attention of scientists soon so it can be studied and protected.

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 178: The Koolakamba

Let’s learn about another mystery ape, the koolakamba (also spelled kooloo-kamba or other variations)!

Further reading:

Between the Gorilla and the Chimpanzee

The Yaounde Zoo mystery ape and the status of the kooloo-kamba

Mystery of the Koolakamba

Antoine the Yaounde Zoo ape, supposedly a koolakamba:

Mafuka (sometimes spelled Mafuca):

A rare photo of the Bili ape:

A handsome western gorilla:

A handsome western chimpanzee:

A western chimpanzee mother and baby:

Show transcript:

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

This week we’re going to round out our bonus mystery animal month with a mystery ape called the koolakamba. Every time I think we’ve covered every mystery ape out there, I find another one.

The koolakamba first appears in print in the mid-19th century, but let’s fast-forward to 1996 first and talk about a photograph of a purported koolakamba. The picture was taken at the Yaounde Zoo in Central Cameroon in Africa, and the ape was a male called Antoine. He has very black skin on his face but bright orange eyes, with a pronounced brow ridge. The picture appeared in the November 1996 issue of the Newsletter of the Internal Primate Protection League and some people suggested the ape was a hybrid of a chimpanzee and a gorilla. That’s what a koolakamba is said to be, a chimp-gorilla hybrid.

But that’s not what the koolakamba was always said to be. So let’s go back again to find out what the first European naturalists reported about this animal.

The first European to write about the koolakamba was a man called Paul DuChaillu. He was also the first European to write about several other animals, including the gorilla, and he was always eager to find more and describe them scientifically. He was the one who gave the koolakamba its name, which was supposed to be a local name for the animal, meaning “one who says ‘kooloo.’” In other words, the ape’s typical call was supposed to sound like it was saying kooloo. I’ve chosen the spelling koolakamba for this episode, as you’ll see in the show notes, but I’ve also seen it as kooloo-kamba with various spellings.

Chimpanzees and gorillas were well known to the local people, of course, but although they weren’t quote-unquote discovered until much later, early travelers to Africa mentioned them occasionally. The first mention of both dates to about 1600. In 1773 a British merchant wrote about three apes he heard about from locals: the chimpanzee, the gorilla, and a third ape called the itsena.

DuChaillu thought the koolakamba was a separate species too, one that looked similar to both the gorilla and the chimpanzee. Other explorers, big game hunters, and zoologists thought it was a chimp-gorilla hybrid, which accounted for its similarity to both apes. A few thought the koolakamba was just a subspecies of chimp, while a few thought it was a subspecies of gorilla.

The argument of what precisely the koolakamba was is still ongoing, but no one ever denied that the koolakamba existed. After all, there were specimens, both dead and alive. In July 1873, a female chimpanzee named Mafuka was shipped to the Dresden Zoo, and she was supposed to be a koolakamba.

We have some beautifully done engravings of her face that are so detailed they might as well be photographs. Mafuka had black skin on her face, pronounced brow ridges, fairly small ears, and a gorilla-like nose. Her hair was black with a reddish tinge. She was also a big ape although she was young, measuring almost four feet high, or 120 cm. She only lived two and a half years in captivity, unfortunately, dying in December of 1875.

Some zoologists classified Mafuka as a young gorilla, while others thought she was a chimpanzee. Others thought she was a hybrid of the two apes. In 1899 an anatomist claimed she was a koolakamba and a different species from either ape.

Other koolakamba apes have been identified after Mafuka, including one called Johanna kept by Barnum & Bailey at the end of the 19th century. But there are more recent examples. A chimpanzee colony kept at the Holloman Air Force Base in New Mexico supposedly had a koolakamba in the 1960s. An ape expert named Osman Hill studied the chimps at Holloman and published his observations in the late 1960s in a comprehensive taxonomy of the chimpanzee. Hill was convinced that the koolakamba was a subspecies of chimp, which he named Pan troglodytes kooloo-kamba.

But Hill’s description of the koolakamba varies from DuChaillu’s description. Basically the only agreements between the two is that the koolakamba has a black face—dark enough that it’s usually referred to as ebony—and pronounced brow ridges.

And that’s the trouble. No one seems able to agree on what the koolakamba actually definitively looks like. Part of the problem is that Europeans who went to Africa to kill animals and claim them as new to science asked the locals what a particular animal was, and assumed that the locals thought about animal relationships the same way Europeans do. That is, we think of animals as distinct species even if they look similar. But many people in Africa, especially hunters, and especially in the 19th century and earlier, approached animals with a different mindset. They needed to know what animals were good to eat, what animals were safe to hunt and which were dangerous and should be avoided, and so forth. Often, they gave different names to the same species of animal based on physical characteristics like size or color. But the Europeans didn’t know this. Many of the local names reported for apes that resemble what we might call the koolakamba translate to things like “gorilla’s brother” and “gorilla-like.”

So there are a lot of things going on here. Let’s see if we can make some sense out of this confusion.

The first big question, of course, is if chimpanzees and gorillas even live in the same parts of Africa. And it turns out they do, at least in a few places in western Africa. Where the territories of chimps and gorillas overlap, they generally avoid each other. It’s rare that they interact at all, and extremely rare that they get in fights. Even if they were feeding in the same small area, they wouldn’t need to fight because they eat different things. Gorillas mostly eat leaves and twigs, while chimps prefer fruit and meat. Also, of course, gorillas stay on the ground while chimps spend most of their time in trees.

So there is enough population overlap that there’s a potential for gorillas and chimpanzees to interact. That doesn’t mean they hybridize, of course. While gorillas and chimpanzees do share a subfamily, they don’t share a genus, which means they’re not very closely related. Chimps are actually more closely related to humans than to gorillas, and we share the same subfamily with both. If you listened to episode 120 about hybrid animals, you may remember that the less closely related two species of animal are, the less likely they are to be interested in mating, the less likely that a pregnancy will result even if they do mate, and the less likely that the baby will survive even if the female does get pregnant. So while it’s extremely unlikely that gorillas and chimps could or would hybridize, it’s not completely out of the question. But even if it does happen, it would be an extremely rare occurrence for a chimp-gorilla hybrid to be born at all, much less live to adulthood.

So we can make a check-mark next to the “hybrid ape” hypothesis, but only a very small check-mark.

Could the koolakamba be a separate species of ape entirely, something new to science? That wouldn’t explain why it’s generally seen in the company of chimpanzees that look like ordinary chimps, not other koolakambas. There are reports that the koolakamba is solitary or only hangs out on the edges of chimp societies, but I can’t find any good sources for these claims and they may not be accurate. If it is a rare species of ape related to the chimpanzee, it shouldn’t be hanging out with chimps. Different species with the same dietary and environmental needs don’t live in the same place. One will always outcompete the other, either driving it to extinction or into another area.

So I’d say no check-mark next to the new species of ape hypothesis.

If you remember episode 102 where we talked about the Bili ape, it turned out that the Bili ape is a population of chimps where the males grow especially large and look gorilla-like. Could the koolakamba actually be the same thing as a Bili ape? The Bili ape is only found in far northern Congo in the Bili Forest, which is close to central Africa, while the koolakamba is only reported from West Africa. So no check-mark for this hypothesis either, although that was a good suggestion.

Chimps can show a lot of variety in facial features, including skin color and ear shape and size, and so on. They also vary in overall body size, just as any animal does. I suspect the main reason that the koolakamba is so often considered a gorilla-chimpanzee hybrid is because the koolakamba’s face is always described as ebony or jet black. This is uncommon in chimps, but all gorillas have dark gray or black skin.

Some populations of the subspecies of chimp that lives in West Africa, the western chimpanzee, are so different from other chimps that some researchers suggest it may be a different species. These populations use spears to hunt, cool off by swimming and playing in water, are more social between tribes than other chimps, and even sometimes live in caves. They also typically live in savannas or open woodland instead of thick forest. Until recently, most observational studies of chimps in the wild have focused on the eastern chimpanzee, so researchers were shocked to learn how different the western chimp is. And the western chimpanzee is generally a little larger than eastern chimps.

It may be the case that the koolakamba isn’t a separate type of animal but a western chimpanzee that shows individual differences that seem striking to us. The fact that even ape experts and local hunters can’t agree on what the koolakamba actually looks like suggests that it’s not a separate subspecies or even a hybrid. It’s just a chimp that happens to have some facial features that look slightly more gorilla-like than other chimps. This is where I would put a nice big check-mark, pending new information.

For all we know, chimps think other chimps with koolakamba-type features are absolutely gorgeous. Or other chimps might think they look a little too gorilla-like, so they might be considered kind of ugly.

I like to imagine a mother chimp looking at her newborn baby and thinking, “Oh my gosh, what a beauty! Look at those distinguished brow ridges and attractive nose. My little baby is going to be the star of the whole troop one day!” But then again, all mothers think that about their babies.

You can find Strange Animals Podcast online 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 a rating and review on Apple Podcasts or wherever you listen to podcasts. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us that way.

Thanks for listening!

Episode 120: Hybrid Animals

If you’re a subscriber on Patreon, you may recognize some of the information in this episode, but I’ve updated it and added a whole bunch. Thanks to Pranav for the topic suggestion!

A cama, llama/camel hybrid:

A swoose, swan/goose hybrid:

Motty the Asian/African elephant hybrid and his mother:

A zorse, zebra/horse hybrid:

Show transcript:

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

This week we’ve got another listener suggestion. Pranav really really wants me to do an episode about hybrid animals, but I’ve been dragging my feet on it because I actually already did an episode on the topic back in 2017—but only for Patreon subscribers. It wasn’t my best episode so for various reasons I’d decided not to unlock it. But Pranav really really wants to learn about hybrids! So I’ve taken part of the Patreon episode and added a lot of newer information to it to bring it up to date and make it more interesting.

The term for an animal with parents of different species is hybrid. Crossbreed is also a common term, although technically a crossbred animal is one with parents of the same species but different breeds, like a labradoodle is a crossbreed of a Labrador and a poodle. Both parents are domestic dogs.

A mule, on the other hand, is a hybrid between a horse and a donkey, specifically a mare and a jack, which is what a male donkey is called. The offspring of a stallion and a lady donkey, known as a jenny, is a hinny.

So why can a horse and a donkey breed while, for instance, a possum and a rat can’t? The two species must belong to the same family, and with very few exceptions, they must also belong to the same genus. The genus is indicated in an animal’s scientific name. Equus caballus is a horse and Equus africanus is a donkey, while a Labrador and a poodle are both Canis familiaris, or Canis lupus familiaris depending on who you ask. The Virginia opossum is Didelphis virginiana while the brown rat is Rattus norvegicus. They’re not even slightly related, although superficially they look alike.

If the hybrid’s parents are from species with different numbers of chromosomes, hybrid males will almost always be sterile. You can’t cross two mules to get more mules, for instance, because male mules can’t make babies. Female mules are sometimes fertile but very rarely conceive. Horses have 64 chromosomes while donkeys have 62. Mules end up with 63. Hinnies are much rarer than mules because if the female of a pair of related species has fewer pairs of chromosomes than the male, it’s less likely that any offspring will result.

More closely related species can have fertile offspring. Killer bees, for instance, are hybrids of a European honeybee and an African honeybee. The two are actually subspecies of the honeybee, Apis mellifera, so it’s less like creating a hybrid and more like crossing a Labrador and a poodle to get an adorable happy pup with curly hair. It seemed like a really good idea. The result was supposed to be a tropical bee that would produce more honey. What actually happened was killer bees. Which do actually kill people. Hundreds of people, in fact, since they escaped into the wild in 1957 and started spreading throughout the Americas.

When animals hybridize even though they aren’t of the same genus, it’s called an intergeneric hybrid. That’s the case with sheep and goats. While sheep and goats are related on the subfamily level, they belong to separate genuses. Sheep have 54 chromosomes while goats have 60. That’s enough of a difference that most hybrid babies don’t survive long enough to be born alive, but it does happen occasionally. Usually the babies have 57 chromosomes, and sometimes the babies survive and even prove to be fertile when crossed with either a goat or a sheep. So that’s weird.

Just because someone wants to find out what you get when you cross, say, a sheep and a goat, doesn’t mean the sheep and goat in question are willing to make that effort. The less closely related the two animals are, the less interested they are in mating. Occasionally hybrids are produced by artificial insemination, or rarely by genetic manipulation of embryos, although genetic manipulation technically results in a chimera, not a hybrid.

Another intergeneric hybrid is a cross between a male camel and a female llama. In this case it’s accomplished by artificial insemination and has only produced a handful of living babies, called camas. Researchers were hoping to produce a camel-sized animal with a llama’s more cooperative temperament, but camas turn out to act like camels. So basically they’re just camels that aren’t as big or strong as camels.

In the 1970s, Chester Zoo in Cheshire in the UK kept a female Asian elephant and a male African elephant together in the same enclosure. The pair mated but no one thought they could produce a hybrid calf, since Asian elephants and African elephants aren’t that closely related. They’re another pair of animals that don’t share a genus. But a calf named Mottie was born in 1978. Surprise!

Many hybrids resemble one or the other of their parents. Motty was a fascinating blend of both. He had five toenails on his forefeet and four on the hind feet like his mom. African savannah elephants like his dad have four front toenails and three hind toenails. But he had longer legs and bigger ears than an Asian elephant. His trunk was wrinkled like his dad’s, but had only one digit at the tip like his mom’s. African elephants have two digits at the tip of their trunks. Even the shape of Motty’s head and back were a mixture of his parents’ characteristics.

So why would anyone want to cross species to get a hybrid? I mean, you might end up with killer bees.

A lot of times hybrids show what is known as hybrid vigor. This is more common in hybrid plants, but some hybrid animals combine the best features of their parents. Mules, for instance, have more stamina than horses and are stronger than donkeys. A hybrid of a domestic cow and an American bison is called a beefalo, which is bred to produce leaner meat in an animal that is better for the environment than a cow but easier to handle than a bison. But a lot of times, hybrids are the result of human ignorance, such as keeping related animals together without realizing babies might result, or human curiosity. We just want to see what might happen.

Unfortunately, for every healthy mule-like hybrid, there’s an unhealthy, malformed, or stillborn animal from parents who should have never produced offspring. Motty the elephant was premature and died of infection when he was only eleven days old, probably because his immune system was weakened due to his hybridized genetics.

Lions, tigers, leopards, and other big cats can all interbreed, but the resulting babies sometimes have unusual health issues. When a male lion and a female tiger breed, the resulting babies are known as ligers, and ligers are enormous. They’re much bigger and heavier than both their parents. This sounds neat, but it happens because of a genetic anomaly that means the animals just grow and grow much faster and longer than a normal tiger or lion cub. This puts stress on the body and can lead to health problems. Ligers can sometimes weigh over 1200 pounds, or over 550 kg, and grow up to 12 feet long, or 3.6 meters, bigger than a full-grown tiger or lion. The offspring of a puma and a leopard, often called a pumapard, has the opposite problem, with cubs usually inheriting a form of dwarfism. The cubs are only half the size of the parents.

The savannah cat is now accepted as a domestic cat breed by some organizations, but it was first developed in 1986 by crossing a female domestic cat and a male serval. The serval is a wild cat from Africa with large ears, long legs, and a spotted and striped coat pattern. It’s a little larger than a domestic cat and is sometimes kept as an exotic pet, although it’s not domesticated. The hybrid babies inherited their mother’s domesticated nature and turned out to be mostly sociable with humans, although some are less tame. But while Savannah cats are pretty, the kittens of a serval and domestic cat are often stillborn or premature, and many male offspring are infertile. Savannah cats are also prone to certain health issues, especially heart problems. Some areas have banned savannah cats since they’re not considered fully domesticated.

The more closely related the parents, the more likely a hybrid baby will result, and the more likely it will be healthy. Many wolf-like canids can and do easily hybridize with other wolf-like canids, since they have 78 chromosomes in the same arrangement and are closely related. Offspring are usually fertile. The wolf-like canids include wolves, domestic dogs, coyotes, jackals, and dholes. Where the ranges of these various species overlap in the wild, hybrids are not uncommon. But canids that are less closely related to the wolf-like canids, like foxes and raccoon dogs, can’t and don’t hybridize with their cousins.

Some whales will hybridize in the wild, including the fin whale and the blue whale, which are closely related. Dolphins of different species sometimes hybridize when they’re kept together in captivity, such as the false killer whale and the bottlenose dolphin. The resulting babies don’t usually live very long. Occasionally dolphins also hybridize in the wild too. In 2017 a hybrid baby of a rough-toothed dolphin and a melon-headed whale, which is actually a species of dolphin, was spotted off the coast of Hawaii. Researchers were able to get a small tissue sample from the young hybrid to DNA test, which confirmed its parentage. The melon-headed whale mother was also spotted with her calf in a pod of rough-toothed dolphins.

Birds also sometimes hybridize in the wild. This happens occasionally where the range of two closely related species overlap. Since the resulting babies may look very different from both their parents, this makes bird-watching even more challenging. Some warbler species hybridize so often that the hybrid offspring are well-known to birders, such as Brewster’s warbler and Lawrence’s warbler. These two birds are both offspring of a golden-winged warbler and a blue-winged warbler mate, with the appearance different depending on which traits the babies inherit from which parent.

Occasionally a domestic chicken will mate with a wild pheasant and produce babies, since chickens and pheasants are related. Very rarely, a swan and goose will mate and produce babies, although the babies don’t usually survive very long. One swan-goose hybrid that did survive was hatched in 2004 in Dorset in the UK, with a mute swan mother and a domestic goose father. The baby was referred to as a swoose and it was the only of the offspring to survive. It looks like a goose but with a longer, more swan-like neck and head.

If you’ve listened to episode 25, part one of the humans episode, you’ll recall that human DNA contains traces of DNA from our extinct cousins, including Neandertals. If Neandertals were still around, we could undoubtedly produce hybrids with them. But what about our living cousins, the other great apes? Humans are closely related to chimpanzees, but could a human produce a hybrid with a chimp? It’s possible but very unlikely. We belong to different genuses and have different numbers of chromosomes, not to mention the enormous ethical issues involved.

Let’s finish up with my favorite hybrid animal, the zebroid. This is a term for any hybrid where one parent is a zebra and the other parent is a horse, a donkey, or a pony, which also leads to the terms zorse, zedonk, and zony. These all crack me up, especially zedonk.

Zebroids are usually at least partially striped, frequently on the legs and neck but sometimes all over. The mane may stand up like a zebra’s or fall over the neck like a horse’s. The zebroid is adorable because of the stripes, but it’s also ornery and can be aggressive. There goes my dream of having a stripy horse.

You can find Strange Animals Podcast online at strangeanimalspodcast.com. We’re on Twitter at strangebeasties and have a facebook page at facebook.com/strangeanimalspodcast. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon if you’d like to support us that way.

Thanks for listening!