Tag Archives: island dwarfism

Episode 318: The Mysterious Malagasy Hippo

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Thanks to the Tracing Owls podcast for this week’s suggestion. I’m a guest on that podcast so make sure to check it out (but while my episode is appropriate for younger listeners, most episodes are not, so be warned).

Further reading:

Huge Hippos Roamed Britain One Million Years Ago

Kenyan fossils show evolution of hippos

The Kilopilopitsofy, Kidoky, and Bokyboky: Accounts of Strange Animals from Belo-sur-mer, Madagascar, and the Megafaunal “Extinction Window”

A sort-of Malagasy hippo:

Actual hippo (not from Madagascar, By Muhammad Mahdi Karim – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=121282994):

A modern hippo skull. There’s a reason the hippo is more dangerous to humans than sharks are [By Raul654 – Darkened version of Image:Hippo skull.jpg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=242785]:

A pygmy hippo and its calf!

Show transcript:

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

This week we’re going to learn about a topic suggested by the host of the podcast Tracing Owls, because I’m actually a guest on that podcast in an upcoming episode! I think the episode releases later this week. I’ll put a link in the show notes, but be aware that while the podcast is interesting and often very funny, with topics that focus on weird stuff related to science, most episodes are not appropriate for younger listeners. (I think my episode should be okay.)

Several years ago now there was a movie called Madagascar, which is about a group of zoo animals that end up shipwrecked on the island of Madagascar. I love this movie, especially the lemur King Julian, but one of my favorite characters is a hippopotamus named Gloria, voiced by Jada Pinkett Smith. The island country of Madagascar is off the southeastern coast of Africa, but as we talked about in episode 77, it’s been separated from the continent of Africa for millions of years and the animals of that country have mostly evolved separately from the animals of Africa. That’s part of why the movie Madagascar is so funny, since the main characters in the movie are all native to Africa—a lion, a zebra, a giraffe, and Gloria the hippo—and don’t know anything about the animals they encounter on Madagascar. Like this guy:

[King Julian clip]

But it turns out that hippos did once live on Madagascar, and that’s what we’re going to learn about today.

We’re not sure when the first humans visited Madagascar, but it was at least 2500 years ago and possibly as much as 9500 years ago or even earlier. By 1500 years ago people were definitely living on the island. It’s likely that hunting parties would travel to Madagascar and stay there for a while, then return home with lots of food, but eventually people decided it would be a nice place to live.

Madagascar is a really big island, the fourth largest island in the world. It’s been separated from every other landmass for around 88 million years, and has been separated from Africa for about 165 million years. Many of the animals and plants that live on Madagascar are very different from the ones living anywhere else in the world as a result.

To put this into perspective, here’s your reminder that the closest living relative of the hippopotamus is the whale, and 60 million years ago the common ancestor of both hippos and whales was a small semi-aquatic animal. That was about 28 million years after Madagascar was on its own in the big wide ocean, and 105 million years after the landmass that we call Africa broke off from the supercontinent Gondwana and began moving very slowly into the position it’s in today. When Madagascar finally broke free of the landmass we now call India, dinosaurs were still the dominant land animal.

So why are there remains of small hippos on Madagascar? How did the hippos get to Madagascar and why aren’t they still around? Did the hippo originate in Africa or in some other place? So many questions!

The ancestors of modern cetaceans, which includes whales and dolphins and their close relations, are found in the fossil record about 52 million years ago, although it might have been 53 or even 54 million years ago depending on which scientist you ask. That’s when the whale side of the suborder Whippomorpha started developing separately from the hippo side. The “morpha” part of Whippomorpha just means “resembling,” and I’m happy to report that the “whippo” part is actually a combination of the words whale and hippo. Truly, it gave me great joy when I learned this fact, because I assumed “whippo” was something in Greek or Latin, or maybe referred to an animal with a whip-like tail. Nope, whale+hippo=whippo.

Anyway, while we know a fair amount about the evolution of cetaceans from their semi-aquatic ancestors, we don’t know much at all about the hippo’s evolution. There’s still a lot of controversy about whether hippos really are all that closely related to whales after all. They share a lot of similarities both physically and genetically, so they’re definitely relations, but whether they’re close cousins is less certain. The confusion is mainly due to not having enough fossils of hippopotamus ancestors.

The modern hippo, the one we’re familiar with today, usually called the common hippo, first appears in the fossil record about six million years ago. We have fossils of animals that were pretty obviously close relations to the common hippo, if not direct ancestors, that date back about 20 million years. But it’s the gap between the hypothesized shared ancestor of both hippos and cetaceans that lived around 60 million years ago, and the first ancestral hippos 20 million years ago, that is such a mystery.

What we do know, though, is that while the common hippo is native to Africa, its ancestors weren’t. Hippo relations once lived throughout Europe and Asia, and probably migrated to Africa around 35 million years ago. In fact, hippos were common throughout Eurasia until relatively recent times. In 2021, a fossilized hippopotamus tooth was found in a cave in Somerset, England that probably lived only one million years ago. That was well before humans migrated into the area, which was a good thing for the humans because this hippo was humongous. It probably weighed around 3 tons, or 3200 kg, while the common hippo is about half that on average.

This particular huge hippo, Hippopotamus antiquus, lived throughout Europe and only went extinct around 550,000 years ago as far as we know. This was during a time that Europe was a lot warmer than it is today and hippos migrated north from the Mediterranean as far as southern England. The common hippo, H. amphibius, the one still around today, also migrated back into Eurasia during this warm period and its fossilized remains have been found in parts of England too.

These days, there are only two living species of hippo, the common hippo and the pygmy hippo. We talked about the pygmy hippo briefly in episode 135, including the astonishing fact that it only grows around 3 feet tall, or 90 cm, and lives in deep forests in parts of west Africa. There also used to be some other small hippos that evolved on islands and exhibited island dwarfism, and which probably weren’t closely related to the pygmy hippo. These include the Cretan dwarf hippopotamus that lived on the Greek island of Crete until around 300,000 years ago and maybe much more recently, and the Cyprus dwarf hippopotamus that lived on the island of Cyprus until only around 10,000 years ago. The Cyprus hippo was the smallest hippo found so far, only about 2.5 feet tall, or 75 cm. There are dogs larger than that! But the small hippo we’re interested in is the Malagasy pygmy hippopotamus.

There actually wasn’t just one hippo species that lived on Madagascar. Scientists have identified three species, although this may change as more studies take place and as new remains are found. The different species probably didn’t all live on the island at the same time, and some researchers think they might have resulted from three different migrations of hippos to the island.

But how did they get to the island? Madagascar is 250 miles away from Africa, or 400 km, way too far for a hippo to swim. The Malagasy hippos were well established on the island, too, not just a few individuals who accidentally reached shore. That means there must have been some way for hippos to reach Madagascar fairly easily at different times.

The best hypothesis right now is that at times when the ocean was overall shallower than it is now, such as during the Pleistocene glaciations, there are enough small islands between Africa and Madagascar that hippos could travel between them pretty easily. Since those islands would be far underwater now, we don’t have any way to know for sure. We can’t exactly dive down and look for hippo fossils, unfortunately.

The really big question, of course, is whether any hippos still survive on Madagascar. We know they were around as recently as 1,000 years ago, because we have subfossil remains. (Just a reminder that subfossil means that the remains are either not fossilized, or only partially fossilized.) Not only that, the bones show butchering marks so we know people killed and ate the hippos. Right now scientists think the hippos were hunted to extinction by the humans who settled on Madagascar, but there’s some evidence that it happened much more recently than 1,000 years ago.

Over the last several hundred years, European colonizers of Madagascar collected stories from Malagasy natives about animals that resemble hippos. More recently, some stories have also been collected by scientists.

In 1995, a biologist named David Burney, who was studying recently extinct animals on Madagascar, interviewed some elderly residents in various villages. He wasn’t actually trying to learn about mystery animals, he was mostly just trying to find the paleontological sites scientists had found decades before. He figured the older residents would remember those scientists’ visits, and he was right. But the residents also had other stories to tell about the bones dug up by scientists. Some of them said those bones belonged to animals they had seen alive.

In one village, several different people told a story about a cow-sized animal that had occasionally entered the village at night. It was dark in color and made distinctive grunting sounds, and had large floppy ears. When some people approached it too closely, it ran back to the water and submerged.

Dr. Burney thought the residents might have seen pictures of an elephant and transferred some of its details to the mystery animal, especially the large size and floppy ears. But when he showed a picture of an elephant to them, they were clear that it wasn’t the same animal. They chose a picture of a hippo instead, but said the animal they’d seen had larger ears. Various witnesses also said the animal had a large mouth with really big teeth, that its feet were flat, and that it was the size of a cow but didn’t have horns. One man even imitated the animal’s call, which Burney reported sounded like a hippopotamus even though the man had never seen or heard a hippo.

Burney was cautious about publishing his findings, and in fact in his article he mentions that even at the time, he and his team of scientists were cautious about even pursuing information about living Malagasy hippos. They didn’t want to be seen as acting like cryptozoologists, which says a lot about how cryptozoologists conduct their research. Cryptozoology isn’t a scientific field of study despite its name. Biologists, paleontologists, and other experts research mystery animals all the time. That’s just part of their job; they don’t have to call themselves something special. It’s unfortunately common that people who call themselves cryptozoologists don’t have a scientific background and may not know how to conduct proper field research. Very often, cryptozoologists also don’t know very much about the animals that definitely exist, and how can you determine what a true mystery animal is if you don’t know about non-mystery animals?

Luckily, Dr. Burney and his team decided to pursue this particular mystery animal, along with some others they learned about. The last hippo-like animal sighting they could pin to a particular date happened in 1976. If the animal in question was a hippo, and it really was alive only about 50 years ago, it might have gone extinct since then. Or it might still be alive and hiding deep in the forests of Madagascar.

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!

This is what a hippo sounds like, and you hear it all the time on this podcast because I like it:

[hippo sound]

Episode 200: Elephants

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This week we’re going to learn about elephants! Thanks to Damian, Pranav, and Richard from NC for the suggestions!

Further Reading:

Dwarf Elephant Facts and Figures

An Asian elephant (left) and an African elephant (right). Note the ear size difference, the easiest way to tell which kind of elephant you’re looking at:

Business end of an Asian elephant’s trunk:

An elephant living the good life:

Can’t quite reach:

Elephant teef:

A dwarf elephant skeleton:

An elephant skull does kind of look like a giant one-eyed human skull:

Show transcript:

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

This week we’re going to learn about some elephants! We’ve talked about elephants many times before, but not recently, and we’ve not really gone into detail about living elephants. Thanks to Damian, Pranav, and Richard from NC for the suggestions. Damian in particular sent this suggestion to me so long ago that he’s probably stopped listening, probably because he’s grown up and graduated from college and started a family and probably his kids are now in college too, it’s been so long. Okay, it hasn’t been that long. It just feels like it. Sorry I took so long to get to your suggestion.

Anyway, Damian wanted to hear about African and Asian elephants, so we’ll start there. Those are the elephants still living today, and honestly, we are so lucky to have them in the world! If you’ve ever wished you could see a live mammoth, as I often have, thank your lucky stars that you can still see an elephant.

Elephants are in the family Elephantidae, which includes both living elephants and their extinct close relations. Living elephants include the Asian elephant and the African elephant, with two subspecies, the African savanna elephant and the African forest elephant. The savanna elephant is the largest.

The tallest elephant ever measured was a male African elephant who stood 13 feet high at the shoulder, or just under 4 meters, which is just ridiculously tall. That’s two Michael Jordans standing on top of each other, and I don’t know how you would clone Michael Jordan or get one of them to balance on the other’s head, but if you did, they would be the same size as this one huge elephant. The largest Asian elephant ever measured was a male who stood 11.3 feet tall, or 3.43 meters. Generally, though, it’s hard to measure how tall or heavy a wild elephant is because first of all they don’t usually want anything to do with humans, and second, where are you going to get a scale big and strong enough to weigh an elephant? Most male African elephants are closer to 11 feet tall, or 3.3 meters, while females are smaller, and the average male Asian elephant is around 9 feet tall, or 2.75 meters, and females are also smaller. Even a small elephant is massive, though.

Because of its size, the elephant can’t jump or run, but it can move pretty darn fast even so, up to 16 mph, or 25 km/h. The fastest human ever measured was Usain Bolt, who can run 28 mph, or 45 km/h, but only for very short distances. A more average running speed for a person in good condition is about 6 mph, or 9.6 km/h, and again, that’s just for short sprints. So the elephant can really hustle. Its big feet are cushioned on the bottoms so that it can actually move almost noiselessly. And I know you’re wondering it, so yes, an elephant could probably be a good ninja if it wanted to. It would have to carry its sword in its trunk, though. The elephant is also a really good swimmer, surprisingly, and it can use its trunk as a snorkel when it’s underwater. It likes to spend time in the water, which keeps it cool, and it will wallow in mud when it can. The mud helps protect it from the sun and from insect bites. Its skin is thick but it’s also sensitive, and it doesn’t have a lot of hair to protect it.

The elephant is a herbivore that only eats plants, but it eats a lot of them. An adult elephant eats several hundred pounds of food a day, or more than 100 kg, and will drink enough water every day to fill a bathtub. It eats grass, leaves, twigs, fruit, and bark, and elephants in captivity also eat hay. And since we’re getting close to the winter holidays, some zoos have an agreement with Christmas tree sellers, who donate any unsold Christmas trees to the zoos for the elephants to eat. They can’t feed used trees because there might be leftover ornaments or ornament hangers on them. The elephant just puts one foot on the tree and rips off the branches with its trunk, which it then eats.

The elephant has a pair of big teeth on each side of its mouth that look more like the bottoms of running shoes than ordinary teeth, which it uses to grind up the tough plants it eats. Elephants technically have 26 teeth, two incisors and 24 molars. The incisors are modified into tusks, which we’ll talk about in a minute. The molars aren’t all in the mouth at once, though. Every so many years, the four molars in an elephant’s mouth start to get pushed out by four new molars. It doesn’t happen the same way you lose your baby teeth, though. Instead of a new tooth pushing up through the gum until the baby tooth gets loose and falls out, the new molars grow in at the back of the mouth and start moving forward, pushing the old molars farther forward until they fall out. This happens six times throughout the elephant’s life, with the last set usually growing in around the early 40s. Since elephants can live much longer than that, well into their sixties, that last set may have to last a long time, since there are no elephant dentists that can make gigantic elephant dentures.

The tusks are much different than the molars, naturally. The tusks start to grow from the upper jaw when the elephant is a little over six months old, and continue growing throughout its life. It uses its tusks for all kinds of activities, including moving obstacles from its path, digging for water, and defending itself. But not all elephants have tusks. Many Asian elephants don’t have tusks at all, or only have very small ones. Because poachers who want the tusks to sell as ivory shoot elephants that have the biggest tusks, many populations now have smaller tusks overall or none, since elephants without them are less likely to be killed.

The elephant’s trunk is strong but sensitive, sort of like a human’s arm and hand but with many more uses (and also no bones). The elephant breathes and smells through its trunk, since it’s an extension of the nose and upper lip, but it also makes noise with its trunk to communicate with other elephants, uses it to gather food and move it into the mouth, sucks up water with the trunk and splooshes it into the mouth to drink or onto its body to wash. It can reach plants that are way up high or it can dig into soft ground for roots or to reach water. It can open nuts with its trunk, scratch an itch, play wrestle with a friend, lift incredibly heavy things out of the way, and all sorts of other things. Elephants probably wonder how humans can function without a trunk. I am starting to wonder how I function without a trunk.

The easiest way to tell an Asian elephant apart from an African elephant is by looking at the ears. African elephants have much larger ears, especially savanna elephants. The ears are full of small blood vessels to help release heat from the body into the atmosphere. An elephant will flap its ears to stay cool on a hot day. Asian elephants are also smaller overall and have a different body shape. Asian elephants have somewhat shorter legs, a bulkier forehead, different numbers of toes on the feet, and even different trunks. The African elephant has two little projections at the tip of the trunk that act as fingers, while the Asian elephant only has one.

Elephants evolved in what is now Africa and are the largest land animals alive today. The earliest elephant ancestors lived around 56 million years ago, not long after the extinction of the non-avian dinosaurs. It was still a small animal then, only about a foot tall at the shoulder, or 30 cm. It probably spent a lot of time in the water, eating plants, and it probably had small ears and a large nose, but not an actual trunk. If you could go back in time and look at it, you’d never guess that it was an ancestral elephant.

By 27 million years ago, though, elephant ancestors were starting to look like elephants. Eritreum was a lot bigger, over four feet tall at the shoulder, or 1.3 meters, and it probably had short tusks and a trunk. If you looked at a living Eritreum, you’d definitely know it was a kind of elephant, even though it would have looked weird compared to modern elephants since its head was long and flattened in shape. Eritreum already had the same tooth system that modern elephants have, where new molars continually grow and replace worn-out older ones.

Eritreum’s descendants spread to Eurasia and then to North America. By about 2.5 million years ago, at the beginning of the Pleistocene, elephants were all over the place–not just the ancestors of modern elephants, but relations from other parts of the elephant family tree. This includes Palaeoloxodon, a suggestion by Richard from NC.

Palaeoloxodon namadicus lived throughout much of Asia, with fossils found in India, Japan, and Sri Lanka, and it was enormous. We don’t have a complete skeleton, but estimates of Palaeoloxodon’s size suggest it was the largest elephant that we’ve ever discovered. An estimate of the largest specimen found so far is 17.1 feet tall at the shoulder, or 5.2 meters. This is about the same height at the shoulder as Paraceratherium, which we talked about in episode 50 about tallest animals, but it might have actually been taller than Paraceratherium. The tallest giraffe ever measured was 19.3 feet tall, or 5.88 meters, but that’s at the top of its head, not its shoulder, and giraffes are much less heavy than elephants. Whichever one was actually tallest doesn’t really matter, though, because they all belong to the Ridiculously Tall Animals Club, also known as the Animals That Could Squish You Flat by Accident Club.

We don’t know much about Palaeoloxodon since so few fossils have been found so far. We mostly just know it was a massive animal that probably went extinct 24,000 years ago. That’s really not that long ago in geologic terms. It was probably a member of the straight-tusked elephants, a group of animals that were mostly quite large even for elephants.

Straight-tusked elephants weren’t actually straight-tusked, just straighter than most elephant tusks. They all also had an unusual feature on the head called a parieto-occipital crest, which was a ridge of bone high up on the forehead above the eyes that jutted out. The crest was barely noticeable in young elephants but grew larger as the elephant matured, and researchers think it was the attachment site for massive neck muscles to hold up the animal’s massive head.

One interesting thing about Palaeoloxodon is that some other members of the genus were dwarf species that lived on some Mediterranean islands. Pranav wanted to learn about these and other pygmy elephants of the Mediterranean Islands. Fossil elephants have been found on many islands, including islands in the Mediterranean, in south Asia, and the Channel Islands off the coast of California, although they weren’t all closely related. I think we’ve talked about insular dwarfism before, but let’s go over it again briefly. When a large animal like an elephant becomes restricted to a small environment, like an island, there aren’t enough resources for a full population of full-grown animals. As a result, only smaller individuals get enough food to thrive well enough to reproduce, which means their babies are more likely to be smaller too. Over time this results in a population of animals that are much smaller than their relations who don’t live in a restricted environment.

The opposite of insular dwarfism is island gigantism, by the way. When species that are small ordinarily, like pigeons, colonize an island where there are plenty of resources and very few or no predators, they evolve into much larger animals, like dodos.

Insular dwarfism isn’t just about mammals. Palaeontologists have identified dwarf species of dinosaur too, including a pocket-sized sauropod. Okay, maybe not pocket-sized since they still grew nearly 20 feet long, or 6 meters, but since their mainland relations could grow 100 feet long, or 30 meters, that’s a big difference.

Anyway, back to dwarf elephants. It’s so easy to get distracted by all this neat information. The elephants that lived in the Mediterranean islands were mostly straight-tusked elephants, although at least one was a type of mammoth. During the Pleistocene, when a lot of the world’s water was frozen in enormous glaciers, the sea levels were much lower. This exposed a lot more land, and of course animals lived on that land. Then, during the interglacial periods when much of the ice melted and sea levels rose, animals moved to higher ground and eventually some were cut off from the mainland and lived on islands. All of these species that survived exhibited insular dwarfism. It’s helpful to remember that the islands we’re talking about are mostly pretty big. I mean, they’re not the size of Gilligan’s Island. People live on many of these islands today and there are cities and towns and farms and national parks and so forth. The island of Crete, for instance, which is a part of Greece, is 3,260 square miles in size, or 8,450 square km.

One dwarf elephant that once lived on Crete may have only grown 3.7 feet tall at the shoulder, or 1.13 meters. That was the mammoth relation, but a species of Palaeoloxodon also lived on Crete, although not necessarily at the same time as the dwarf mammoth. As the sea levels rose and fell over the centuries, different species of elephant and other animals ended up living on the islands at different times.

We don’t know a whole lot about these dwarf elephants, unfortunately, since we don’t have a lot of remains. Mostly we have teeth, which do tell a lot about the elephant but not everything. But we do know roughly when the various species finally went extinct, and you will not be surprised to learn that these dates often coincide with human arrival on the islands. The Tilos Island elephant probably didn’t go extinct until 6,000 years ago. That’s well into the modern era, and humans lived or at least hunted on the island starting around 10,000 years ago. If you are Greek, your ancestors may have hunted Tilos Island dwarf elephants. It grew up to around 5 feet 3 inches tall, or 1.6 meters, which coincidentally is my height.

Many historians think that the bones and fossils of dwarf elephants may have led to the legend of the cyclops in ancient Greece. The skull of an elephant has a big opening in the front for the nasal passages, with relatively small eye sockets on the sides of the skull. If you’re not familiar with living elephants and you see an elephant skull, it really does look like an enormous human skull with one eye socket in the middle of the forehead.

All elephants live in small family groups that consist of a leader, called the matriarch, who is usually the oldest female in the group, and her close relations and their babies, usually her daughters and grandchildren. When a young male elephant grows up, he leaves his family group, but daughters usually stay.

Although elephants live in these small groups, they’re social animals. The family groups interact with each other when they meet, and they may meet up purposefully just to say hi. A family with a lot of babies may meet up with another family for help taking care of the young ones. When a member of the group is in estrus, meaning she can get pregnant, local males will join the group and try to get her attention. But although the males don’t spend all their time with family groups, they make friends with other males and sometimes form small bachelor groups of their own led by an older male. The older male not only teaches the younger ones how to find food and react to danger, he keeps them from running wild and acting up. During the 1990s, a nature reserve in South Africa introduced a lot of young males that were orphaned and had no family–but without an older male to keep them in line, they went on a rampage and killed 36 rhinoceroses. Finally the park introduced an older male and he put a stop to all that. The young elephants straightened up and left the rhinos alone.

Females usually come into estrus during the rainy season, which is in the second half of the year in Asia and parts of Africa. During this time, mature males may enter a condition called musth for at least some of the time. During musth a male is more aggressive and struts around showing off. It’s easy to tell when a bull elephant is in musth because a gland on each side of his face releases fluid that makes his cheeks wet. Females prefer to mate with males in musth, and usually in a group of males only the most dominant male will be in musth.

Elephants these days are all threatened by poaching, especially for their tusks. Elephant tusks are known as ivory, and ivory sales are banned throughout most of the world. Unfortunately, people still kill elephants to sell the ivory on the black market. Elephants are also threatened by habitat loss, since they need a whole lot of land to find enough to eat and people want that land for their domestic animals or crops.

I could go on and on about elephants for hours. There’s so much to learn about them that it’s just not possible to fit into one podcast episode. I haven’t even touched on their intelligence, their use as working animals in Asia and other parts of the world, and many other interesting things. But we’ll finish with this interesting fact: elephants are afraid of bees, so farmers can keep elephants from eating their crops by making a fence out of bee hives.

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 099: Island Life

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Those of us in the northern hemisphere are thinking a lot about island life right about now, where it’s warm and sunny. But there are islands everywhere, not just the tropics, and the animals on islands often evolve to look strange and different from their mainland cousins. Thanks to Richard E. and Lucy for their suggestions this week!

A fossa:

A tamaraw, miniature water buffalo:

A Socotra starling, my new favorite bird:

Adorable little Galapagos penguin:

A dragonblood tree, good grief!

A blue baboon. It’s not a baboon but it is blue:

A ground dragon:

Further listening:

The unlocked Patreon bonus episode about vampire finches on the Galapagos Islands

Show transcript:

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

In a lot of episodes, we talk about animals from islands like the Galapagos and the Canaries. There’s a reason why islands give rise to strange animals. This week we’ll focus on island life—how island habitats lead to unique animals and how introduced animals can destroy an entire island ecosystem in a matter of a few years. Massive thanks to listener Richard E., who suggested the topics of introduced animals and island life!

Islands, of course, are surrounded by water and isolated from larger landmasses as a result. Some are close to the mainland so it’s easy for animals to swim or float across to the island. In cold areas, animals can sometimes walk across ice to islands. But other islands are more remote, or used to be close to the mainland but were pushed farther away by tectonic forces.

Once a piece of land is cut off from the mainland, the animals and plants on that piece of land start to evolve independently of the larger population of animals and plants on the mainland. If the island is isolated enough that potential predators can’t get to it, the animals already living on the island start to adapt to life with no or few predators. As a result, they may appear tame when humans arrive.

And that is where the problems start. Humans don’t just arrive alone. We bring other animals with us, either on purpose, like dogs, cats, and livestock, or by accident, like rats and mice. And these animals, along with humans, can destroy an entire island habitat really easily.

I’ll use one of Richard’s examples, since it’s a good one and not one you’d think of when thinking of islands. The red squirrel is native to Europe and parts of Asia, but it also lives in the UK and Ireland. It’s usually red-brown in color, although some populations can be brown, gray, or even black. The belly is white. It has long ear tufts and a poofy tail. It lives in trees and eats seeds, nuts, berries, fungi, and occasionally eggs or baby birds.

But remember, Ireland and the UK are islands. And in the 1870s, someone thought it would be really great to import eastern gray squirrels from North America and release them in parks in the UK. In Ireland, in 1911 someone gave a bunch of gray squirrels as a wedding gift, which is not a great gift, honestly, and they got loose because of course they did. They’re squirrels.

Grey squirrels are larger than red squirrels and don’t have ear tufts. They eat the same foods red squirrels do. They also carry a disease called squirrel parapoxvirus that doesn’t bother them but which kills red squirrels. The population of red squirrels has dropped substantially as introduced gray squirrel populations climb in the UK and Ireland. The red squirrel is now protected, with conservation efforts in place that are making a difference. But that just goes to show how easy it is to lose even a well-established species on large islands when an outside species is introduced.

On islands, especially smaller islands, small animals tend to grow larger overall and big animals tend to grow smaller overall. This is called Foster’s rule. It comes about partly because there are fewer predators but limited resources. Small animals don’t need to hide as carefully from predators, large animals may not be able to get enough to eat, but medium-sized animals are able to survive short famines without starving and can take advantage of some resources smaller or larger animals couldn’t use.

One example of island gigantism is the fossa, a predator from Madagascar. If you’ve seen the Madagascar movies, you might remember the fossa as a scary predator that looks something like a big cat. Well, the fossa is a real animal, but it’s not related to cats. It’s related to the mongoose, which is a weasel-like animal, but the fossa is generally much larger than a mongoose. It grows some five feet long, or 1.5 meters, including its tail, although its legs are short compared to those of a similarly-sized cat. It spends a lot of time in trees, where it uses its long tail to help it balance. It’s reddish-brown with a paler belly and eats lemurs and other mammals, birds, insects, crabs, lizards, and even fruit.

An example of island dwarfism is the tamaraw from the island of Mindoro in the Philippines, also called a Mindoro dwarf buffalo. It looks like its close relative, the water buffalo, but is much smaller, only about three and a half feet tall at the shoulder, or 105 cm. It’s like a pocket-sized water buffalo. It has V-shaped horns and is black with some white markings on the legs. It prefers to live in mountainous forested areas with water nearby, and it eats grass, young bamboo shoots, and wild sugarcane. It’s a solitary, shy animal.

Famously, Charles Darwin worked out the theory of evolution after examining the differences in finches living on the various Galapagos Islands. He had actually already started thinking along these lines before he’d really examined the finches, but they supported his ideas and helped him work out the details. Basically, as Darwin eventually determined, a type of finch had colonized the islands at some point in the far distant past. Each island had slightly different ecology, so although the finches could fly, over the years populations living on separate islands began to adapt to better fit the resources available on those islands. For instance, the large ground finch has developed a short, heavy bill to crack nuts, while the closely related vampire ground finch has a thinner, sharper bill that it uses to eat insects, seeds, and the BLOOD OF OTHER BIRDS. I am totally not making this up. In fact, I covered the vampire finch in a patreon bonus episode earlier this year. It’s already unlocked for anyone to listen to, so if you haven’t listened to it and want to, I’ll put a link in the show notes.

Remember that squirrel disease I mentioned earlier? There’s a bird disease called avipoxvirus, or avian pox, that has affected the Galapagos finches since 1898. Researchers think it was probably spread by humans who brought infected domestic birds with them on ships. Fortunately, it hasn’t driven any finches or other birds to extinction.

Another problem brought to the Galapagos Islands by humans, this one spread more recently by tourist boats, is a parasitic nest fly that kills baby birds. Researchers have started leaving cotton balls treated with a mild insecticide where the flies are known to attack endangered finches. The parent finches use the cotton balls to line their nests, which helps protect the babies once they hatch. The nest flies lay their eggs in the nests, and the larvae bite babies and mother birds and drink their blood, which can kill the babies. So far the treatment has helped reduce the number of larvae that hatch.

There’s another bird that lives on the Galapagos that is unique to the islands, and that’s the Galapagos penguin. Thanks to Lucy, who suggested it as a topic, and a shout-out to Lucy’s sister Willa too!

Lucy also wanted to hear about King and Gentoo penguins, so let’s start with them. Both species mostly nest on islands.

The King penguin is almost as big as the Emperor penguin and looks very similar, not surprising since they’re closely related. It stands over three feet tall, or 100 cm. It eats small fish, squid, and krill. Females lay one egg at a time and after the egg hatches, the baby spends its first month or so of life sitting on one parent’s feet while the other parent forages. After that both parents leave the baby in a communal nest, called a crèche, while both go foraging. A young king penguin won’t be able to fish for itself until it’s more than a year old.

The Gentoo penguin lives off the southern tip of South America, and it’s almost as tall as the king penguin, but it’s not closely related to the king and emperor penguins. The Gentoo penguin has a reddish bill and a white stripe on its head above its eyes. The female usually lays two eggs in a nest made of round stones. Gentoo penguins value good nesting stones, and a male may court a female by offering her high-quality stones. Sometimes he has stolen those good stones from other penguin nests. Watch out, ladies. The Gentoo penguin eats krill and other small crustaceans for the bulk of the diet, and also eats fish and squid.

So that gives us a sort of baseline of ordinary penguins to compare to the Galapagos penguin. All other penguins all live in the southern hemisphere, usually not all that far from Antarctica. Part of the Galapagos Islands are in the northern hemisphere, although just barely. Penguins are adapted to severe cold, so how do Galapagos penguins thrive near the equator? As it happens, the waters around the Galapagos are actually quite cold, with various oceanic currents bringing cold water north from the Antarctic and bringing cold water from the depths to the surface in the area. Unlike other penguin species, which often travel widely to find food, the Galapagos penguin stays near the islands where the water is comfortably cool and there’s enough food. On hot days, penguins go into the water to stay cool.

The Galapagos penguin is only about 19 inches tall, or 49 cm. It’s almost the smallest penguin and is definitely the rarest penguin, with only about 1,000 breeding pairs. It mates for life and females lay one or two eggs, making sure to lay eggs in the shade so they won’t get too hot in the sun. If both eggs hatch, the weaker baby usually dies as the parents concentrate on feeding the stronger one. Then again, in good years, grown babies who have moved out of the nest may continue to beg their parents for food and sometimes get fed. I know some people like that. In addition to ordinary predators like seals and hawks, the Galapagos penguin is also vulnerable to introduced predators like cats.

We’ve talked a lot about the Galapagos Islands, but every island has its own unique ecosystem. For example, the island of Socotra lies in the Arabian Sea off the coast of Yemen. It’s only 82 miles long, or 132 km, and 31 miles wide, or 50 km. There are three other, smaller islands nearby. It’s been so isolated for so long that even its trees are bizarre-looking, like the dragon’s blood tree that has dense branches with leaves sticking up at the very top so that it looks like grass growing on top of a weird tree-shaped cliff. The tree also has red sap that has been traditionally used as a dye or varnish.

Humans have lived on the Socotra for 2,000 years, so many endemic species have gone extinct due to habitat loss, hunting, and competition or predation by introduced animals like cats and cattle. But there are still a lot of unusual animals that are found nowhere else in the world. The island has only one native mammal species, a bat, and no amphibians, but it has lots of reptiles and some birds found nowhere else in the world. For instance, the Socotra starling. It’s a large, beautiful songbird with a black body and soft gray head and neck, a heavy black bill, and a black eye with a thin white eye ring. It eats insects and fruit. Socotra is also surrounded by coral reefs with lots of unique fish and crabs.

One interesting animal that lives on Socotra Island is called the blue baboon. But it’s not a baboon or any other kind of primate. It’s not even a mammal. It’s a tarantula, and it’s beautiful! It’s a lovely indigo blue in color with white hairs on the abdomen and the top joints of the legs. Its legspan is about five inches across, or 12 cm, and males are smaller than females. Unlike most other tarantula species, it tolerates others instead of being solitary, so people often keep them as pets. Fortunately, it’s become so popular in captivity that there are lots of captive-bred blue baboons readily available, so the market for illegally collected wild specimens has diminished.

I’ve talked a lot about how animals in island habitats can be driven to extinction very easily, but there are success stories too. For instance, the island of Redonda. It’s a tiny island in the Caribbean, only about a mile long, or 1.6 km, with no source of fresh water and land that’s basically just rock. For centuries no one bothered Redonda because no one wanted to live there, but in the late 19th century it was mined for bird guano, or bird poop, which was used as fertilizer. This went on until 1914, and then in 1929 a hurricane destroyed what was left of the mining equipment. The few people who lived there left, but there were still rats and feral goats that ate everything they could find.

Redonda might have become a wasteland with nothing but rats, goats, and a few birds, but an ambitious conservation effort is paying off. First, the rats and goats were trapped and removed from the island. The rats were mostly killed, but the goats were taken to nearby Antigua where they’ve found homes. Then—and this is important—people left the island alone. Without introduced species and without human interference, the population of endemic animals have begun to rebound. Native plants and trees have started growing back. Rare seabirds nest there again. Instead of a big rock, the island now appears green again.

And the population of lizards on the island is rebounding like crazy. In just a year, the number of ground dragons has almost doubled. Ground dragons are lizards only found on the island. They’re shiny black with long tails and eat pretty much anything they can catch, including young ground dragons.

Sometimes all it takes for nature to be set right is to just leave it alone to do what it does best. Sometimes humans have to help by restoring keystone species to a habitat. This has happened with giant Aldabra tortoises, which were once common on the island of Mauritius, the same island where the dodo once lived. A species of ebony tree had nearly been driven extinct by logging, but even after logging was stopped in the 1980s, the trees hadn’t rebounded. Researchers determined that giant tortoises had once eaten the ebony tree fruit and pooped out the seeds, much like the dodo and the rare dodo tree palm. When giant tortoises were reintroduced to Mauritius, new ebony trees started to sprout.

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!