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Episode 241: Weird and Wonderful Squirrels

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Thanks to Liesbet and Enzo for their suggestions this week! Let’s learn about squirrels!

Further reading:

Project Squirrel

Interspecies Breeding Is Responsible for Some Squirrels’ Black Coloring

The Indian giant squirrel, without filter (left) and with filter (right):

Some variable squirrels (see lots more at iNaturalist):

The Eastern gray squirrel:

The Eurasian red squirrel:

The fox squirrel:

White Eastern gray squirrels (photos taken from the White and Albino Squirrel Research Initiative):

A white variable squirrel spotted in Thailand (picture found here):

The African pygmy squirrel:

The least pygmy squirrel of Asia:

Show transcript:

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

It’s finally the squirrel episode! Both Liesbet and Enzo have suggested squirrels as a topic, and Enzo specifically asked about white squirrels, hybrid squirrels, and squirrels in danger. We’re going to cover all those, and also a few squirrel mysteries!

First, though, a quick note to say that the Kickstarter campaign for the Strange Animals Podcast book is definitely going to happen NEXT MONTH! It’ll go live in early October 2021. Don’t worry, I’ll let you know when so you can go pre-order a copy of the book if you want, and in fact I think I’ll do a bonus episode the first day of the Kickstarter. If you want to get an email to remind you when the campaign launches, there’s a link in the show notes to the pre-launch page where you can request an email notification on launch. You can also see what the book cover will look like! Now, on to the squirrels.

The animal we generally just call a squirrel is specifically a tree squirrel, as opposed to ground squirrels. Tree squirrels are arboreal, which means they live in trees, although they spend plenty of time on the ground too. Squirrels mostly eat nuts and seeds, including acorns and the seeds inside pine cones, but will also eat berries, flowers and buds, tree bark and sap, fungus, and sometimes insects, bird eggs, and even baby birds. Squirrels are rodents and are active in the daytime.

Squirrels can be helpful to trees even though they eat tree nuts, because most species bury nuts to dig up and eat later. The squirrel doesn’t always remember where it hid all its nuts, and in spring the buried nuts sprout and grow into new trees. Some species also hide nuts in caches, often in holes in trees.

A squirrel sleeps in a nest made of dead leaves and sticks it builds in the branches of a tree. The nest is called a drey and it’s lined on the inside with moss, grass, and other soft, warm material. A mother squirrel will line the nest with some of her fur right before her babies are born, so the nest is especially soft and warm. Some species also nest in old woodpecker holes. In winter when it’s cold, several squirrels may share the same drey to stay warm, but squirrels are usually solitary. They don’t hibernate, but like most of us, they sleep more in winter and are less active.

Most people know what a squirrel looks like, because it’s such a common animal throughout most of the world. Some squirrel species get used to humans and often live in people’s yards and in city parks. A tree squirrel has a long, fluffy tail, a long, slender body, relatively short legs, small ears, and large eyes. It’s usually gray or brown and sometimes has spots or stripes.

Some tree squirrels look different from the squirrels you may be used to, depending on where you live. Squirrels of the genus Ratufa are called giant squirrels and they’re the size of domestic cats. They live in parts of Asia, especially southeast Asia. The Indian giant squirrel lives in India, and not only is it especially big, up to 20 inches long, or 50 cm, not counting its long tail, it’s brightly colored. Different individuals and subspecies can have different shades of fur, although the belly and front legs are usually cream-colored. The rest of the body can be tan, dark brown, black, cream-colored, rusty-red, or even a dark maroon color. You may have seen pictures online of brightly colored giant squirrels, and while those are real pictures of real animals, the photographer used a filter that enhances the colors to make them look even brighter than they really are.

The Indian giant squirrel and its close relations eat fruit, nuts, flowers, and other plant material, and hardly ever come down from the tall trees where they live.

Another colorful squirrel is the variable squirrel, which also lives in southeast Asia. It’s on the small side for a tree squirrel, less than 9 inches long at most, or 22 cm, not counting the tail. There are over a dozen subspecies that vary in color and pattern, and some researchers think there may be enough differences that it’s actually more than one species of closely related squirrel. It’s a member of a genus called “beautiful squirrels,” because so many species in the genus have pretty markings. Some variable squirrels are white underneath and red-brown above, with little pointed ears outlined in white, and a reddish tail. Some are glossy black with red markings. Others can be gray, black, orangey-red, reddish-brown, brown, or white with various patterns and markings. It’s so pretty that it’s been introduced in places like Japan, Singapore, Italy, and the Philippines, where it can be an invasive species.

The eastern gray squirrel of eastern North America has also been introduced to other areas where it’s become an invasive species. It was introduced to the UK in 1876 and because it’s a large, aggressive species, the native Eurasian red squirrel has been driven almost to extinction in Britain. It’s still doing fine in the rest of its range, though. Habitat loss is also a factor in the red squirrel’s declining numbers, but the gray squirrel certainly isn’t helping.

The gray squirrel also carries a disease called the squirrel parapoxvirus that causes squirrelpox. Don’t worry, only squirrels can catch it. The gray squirrel is mostly immune to the disease, but the red squirrel isn’t. If an infected gray squirrel is bitten by a mosquito that then bites a red squirrel, the red squirrel can catch squirrelpox from the mosquito bite.

The red squirrel is a reddish-brown in color with tufts on its ears, and in winter it grows a thick undercoat to keep it warm. It also generally looks more gray in winter. Some populations of red squirrel in parts of Europe are black, or nearly black, although it still has a white belly. The red squirrel only grows up to about 9 inches long, or 23 cm, much smaller than the eastern gray squirrel, which can grow up to 12 inches long, or 30 cm. Those lengths don’t include the tail. The red squirrel generally prefers fir trees while the gray squirrel prefers deciduous trees, especially oaks, but the gray squirrel will steal food from the red squirrel no matter what kind of food it is.

In its native range in eastern North America, the eastern gray squirrel often lives alongside other species of squirrel. In 1997 an evolutionary behavioral ecologist named Joel Brown noticed that there are two species of squirrel that live in Chicago, Illinois, a large city in the middle of the gray squirrel’s range. The gray squirrel shares the city with the fox squirrel, which is about the same size and looks very similar to the gray squirrel but is more of a rusty-red color. Dr. Brown noticed that the gray squirrel mostly lives in wealthy neighborhoods while the fox squirrel mostly lives in neighborhoods where people don’t have as much money, and he wanted to figure out why.

Dr. Brown started Project Squirrel to study the mystery. The program teaches people how to tell the difference between the two species so they can report what kind of squirrels they see and where they see them. Right away he started noticing patterns. Fox squirrels live in areas where there are more predators, including feral and free-roaming dogs and cats, urban foxes and coyotes, and hawks. Gray squirrels prefer areas where there aren’t as many predators. Dr. Brown thinks it’s because the fox squirrels are bolder and on average a little larger than gray squirrels, which tend to be more shy. He even noticed a change in his own neighborhood when gray squirrels started becoming more numerous, a shift that happened right after a local leash law went into effect, meaning that fewer pets were running loose.

Project Squirrel has since expanded. There’s an app and everything if you want to take part as a citizen scientist and help solve squirrel mysteries.

Another small squirrel mystery is white squirrels. In August of 2021, just last month as this episode goes live, we had a Q&A episode where we talked about the black squirrels Connor was seeing in Michigan. Those black squirrels turned out to be melanistic eastern gray squirrels. Are white squirrels albino animals or is there something else going on?

Albinism is due to a genetic anomaly that causes an individual to lack pigment. That means its fur or hair is pure white and its skin looks pink because the lack of pigment means its blood shows through and makes it look pink. Its eyes will look red or pink for the same reason, although in some animals the eyes are pale blue instead. Humans with albinism have pale blue eyes.

But most white squirrels have dark eyes and may appear pale brown or gray instead of pure white. Instead of albinism, these squirrels are leucistic. Leucism is related to albinism but instead of a lack of pigment, a leucistic animal has reduced pigment. Sometimes the reduced pigment happens all over the body, sometimes in patches. A leucistic animal often has ordinary colored eyes and skin but pale or white fur. In some domestic species of animal, leucism is bred for or happens frequently in a population, like piebald horses and cows with white spots. It’s a common enough condition that I’ve actually seen leucistic birds while birdwatching. Humans can sometimes show a type of leucism called vitiligo that usually develops in adults, where patches of skin lose their pigment over time. It’s most noticeable on people with dark skin but it also happens to people with light skin. You can’t catch vitiligo from someone else; it’s just a genetic anomaly. Unfortunately, sometimes people who develop the condition get treated badly by others, because people are often afraid of things they don’t understand. Now you know what it is and you can share that knowledge when you need to.

In squirrels, individuals with white fur are usually in more danger from predators. Everything likes to eat squirrels, which is why most squirrel species are gray or reddish-brown as camouflage against tree trunks and branches. A white squirrel shows up like a flashing sign saying, “Snacktime!” As a result, squirrels with white fur are rare to start with and usually don’t live long enough to pass their genes along to the next generation—but in some places, they’re much more common.

In many towns in the United States and Canada, white squirrels are not just common, most squirrels are white. Some towns have white squirrel festivals as a way to promote local pride and bring tourists to the area. Why do some places have white squirrels while most don’t, and why are all the white squirrel populations in North America?

It’s all back to the eastern gray squirrel again. Most squirrel species don’t have a gene that can cause leucism, but the eastern gray squirrel does. Other squirrel species can be albinistic since that’s a genetic anomaly that can happen in any animal, but it’s the eastern gray squirrel that shows leucism most commonly. The closely related fox squirrel also sometimes exhibits leucism.

Some towns have high populations of white squirrels because people think they’re neat. If the white squirrels are in a protected area, like a city park or a college campus, there are fewer predators to start with. People who like the squirrels will leave food out for them and make sure no one hurts them, and as a result the squirrels survive to have babies. Since leucism is a genetic condition, the babies of white squirrels are more likely to be white too.

Remember the variable squirrel we talked about earlier in the episode? Some of them exhibit leucism too, usually a pale brown-white all over with dark eyes.

One thing I learned about black squirrels after last month’s Q&A episode is that some black squirrels are hybrids of eastern gray and fox squirrels. The two species are closely related and often live in the same areas, so it’s not surprising that they sometimes interbreed. Hybrid babies may inherit a genetic variant found in fox squirrels that gives them darker fur. Some researchers think that all gray squirrels with black fur may have inherited the gene for black fur color from fox squirrels in their ancestry.

For the most part, though, tree squirrels don’t hybridize very often, probably because in most places, only one species predominates in any given area. Grey squirrels and Eurasian red squirrels belong to different genera and subfamilies, so aren’t very closely related although their habitats sometimes overlap.

Enzo specifically asked about squirrels in danger, and I’m happy to report that most squirrel species are actually doing just fine. Squirrels are adaptable and can learn to live around humans. As long as they have trees to live in and enough food to support a population, they’re okay. The main danger most squirrels face is habitat loss, especially logging and clear-cutting of forests to build houses or businesses.

A subspecies of fox squirrel called the Delmarva fox squirrel was put on the endangered species list in 1967. It’s native to areas of northeastern North America. It’s about the size of the eastern gray squirrel, which it resembles since it’s gray with a white belly, although it’s usually a more silvery gray in color. By 1967 its population had declined by 90% from habitat loss and overhunting. A conservation plan put in place in 1979 focused on protecting the squirrel’s remaining habitat, restoring its habitat wherever possible, and monitoring the population carefully. The program was such a success that in 2015, the Delmarva fox squirrel was removed from the endangered species list. It’s yet another reminder that protecting an animal’s habitat is just as important as protecting the animal itself. The Delmarva fox squirrel now only lives on the eastern coasts of Maryland and Virginia, a much smaller range than before, so continued conservation efforts are in place to keep it safe and healthy.

Let’s finish with the smallest tree squirrel known, the African pygmy squirrel. It lives in tropical rainforests in parts of western and central Africa. It only grows 5.5 inches long, or 14 cm, and that includes its tail! That’s the size of a mouse. We don’t actually know a whole lot about the African pygmy squirrel, but we do know that it’s an omnivore. This is unusual for squirrels, even though most squirrel species will eat the occasional insect or bird egg. The African pygmy squirrel eats insects regularly as well as fruit, bark, and other plant materials. Unlike most squirrels, it doesn’t store food.

The African pygmy squirrel is the same size as the least pygmy squirrel that lives on three islands in southeast Asia. We know even less about the least pygmy squirrel than we do the African pygmy squirrel…or I guess you could say we know the least about the least pygmy squirrel.

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. There are links in the show notes to join our mailing list and to our merch store.

Thanks for listening!

BONUS Q&A Episode!

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It’s our bonus question and answer episode, which turned out to be ridiculously long but hopefully interesting!

Further listening/watching:

The Axolotl Song

~~~Buy my books!~~~

Whiskers used to have two eyes and a nose. In the background, Dracula (left) and Poe (right):

Black squirrel!

King cobra!

Pufferfish, puffed:

Dog nose:

Show transcript:

Welcome to the bonus Q&A episode of Strange Animals Podcast! I’m your host, Kate Shaw, and this is a little extra episode where I answer listener questions. So let’s jump right into it.

To start us off, Simon and Thia wanted to know how I first became interested in animals. I really don’t know! When I was little, I didn’t want to play with dolls, I wanted to play with my stuffed animals. I actually have a toy cat named Whiskers who I’ve had since I was four. Whiskers is older than all my teeth! I especially loved horses as a kid and since my family couldn’t afford to buy me a horse, I took riding lessons and read everything I could find about horses, fiction and nonfiction. All that reading about horses led to reading about other animals, and the more I read, the more interested I became in animals of all kinds.

Next, Melissa of the awesome podcast Bewilderbeasts asked, “What was the fact or episode that really slapped you out of left field, like, ‘I didn’t see that coming AT ALL’?”

OH MY GOSH, how many times has that happened to me? The most astounding fact I can think of isn’t actually about an animal at all but about trees. While I was researching the Temnospondyl episode, which had a related Patreon episode that ran at about the same time, I came across the fact that when trees first developed, nothing could break down the tough compound called lignin that hardens a tree’s cells to make wood and bark. When a tree died, its trunk just stayed where it fell forever, and this happened for at least 50 million years and possibly 100 million years. 100 million years of tree trunks just lying all over the ground! You wouldn’t be able to walk anywhere! You’d have to climb over hundreds of millions of fallen tree trunks, although naturally as the years passed the older ones would get buried deeper and deeper in the earth. But there would always be more!

This blew my mind, and later I came back to it, determined to do more research and make sure it was accurate. I did a whole lot of research, because it just didn’t seem possible, and that information ended up in episode 214.

As for an animal that blew my mind, I still have trouble believing ice worms are real. They’re worms that live in snow and ice! We covered them last August in episode 185 and I’m still reeling.

Next, Llewelly asks what my favorite extinct animal is, or animals. Why would you make me choose? This is so hard. Okay, fine, I’ll narrow it down to hoofed Pleistocene megafauna like the giant deer and elasmotherium and so many other animals with weird horns and ossicones and things like that. What really gets me is that they lived so recently! Many of them only died out 11,000 years ago, and some were probably around much more recently in a few isolated areas. It also really reminds me to appreciate the megafauna that’s still around. We live at the same time as giraffes!

Next, Richard E. asked, “Does your job involve the study of animals and/or is the pod something that you really wanted to do?” Tracie also asked what my background is, if I’m a professor or zookeeper or something similar. Helenka also asked my background and how I got interested in strange animals.

I’m kind of embarrassed that I never have pointed out that I’m not an animal expert, to steal a phrase from the awesome podcast Varmints! I actually work as a test proctor, AKA invigilator, in a large community college, so my work doesn’t have anything to do with animals. My background is in elementary education although I didn’t teach long. Basically I got my K-8 teaching certification and M.Ed., did some substitute teaching afterwards, and ended up getting my current job instead of taking a teaching position. I still love teaching, so when I decided I wanted to start a podcast, I knew it would be nonfiction. My undergraduate degree is in English literature, and I took so many history courses that I minored in history almost by accident, so I’m really good at research and can write an essay about any topic in the world in very little time. I didn’t know it when I was in college, which was long before podcasts existed anyway, but I have the perfect background for creating a nonfiction podcast.

Liesbet has three questions about the podcast: what inspired me to start it, what motivates me to keep going without missing any episodes, and what I enjoy most about it. I’m so pleased that someone noticed I’ve never missed a single episode! Not that it would be the end of the world if I did, of course, but if I did, I’d feel bad thinking about people who were looking forward to listening to the new episode and were disappointed when there wasn’t one.

Here is the raw, honest truth about why I started Strange Animals Podcast. It was several things combined and the whole story is kind of dumb. First, my friend Kevin makes a great pop culture podcast called The Flopcast, and after I’d listened to it for a while I thought, “Hey, that sounds like fun. I think I’ll start a podcast.” About the same time, I was listening to a back episode of a podcast I will not name, and it gave some misinformation about the Irish elk, specifically the outdated theory that it went extinct because its antlers were too big. I mentioned that in episode 4 and how I kept thinking about it and got kind of angry that a large, influential podcast hadn’t bothered to do enough research about an animal that lots of people are interested in. I decided I could do better and that my podcast would be about animals. Also at the same time, I was trying to find a good podcast about mystery animals that was well researched and didn’t skate off into speculation too much. I couldn’t find one that satisfied me, so I had to make one myself.

I wasn’t exactly sure what my focus would be when I first started the podcast. You can kind of tell when you listen to the first six months or so of the podcast that I was trying out new things and figuring out what worked best and what I liked best. I’m still figuring that out, for that matter.

It’s hard to decide what I like best about making the podcast. I like the whole process, except maybe not the frustrating parts of recording and editing. I think my favorite part has to be when I uncover information I find really exciting. I get to share that information with everyone who listens! It’s fantastic!

Next, let’s get into some questions about animals.

Pranav asked if I would explain how poisons work, which is a great question and also just a tiny bit alarming. No one eat anything Pranav cooks for you unless he’s eating some too. Actually, of course, he’s just wanting to learn more about poisonous animals, and I’ll talk about venomous animals too.

A poisonous animal contains toxins somewhere in its body, like the hooded pitohui bird that we talked about in episode 222 that has poisonous feathers. The poison stops other animals from trying to eat it. In the case of the hooded pitohui, its poison causes your skin to burn when you touch it, so an animal that tries to bite it will have a burning mouth. If it actually eats any of the poison, the animal can die. Many amphibians secrete toxins through their skin, like the poison dart frog, and many other animals concentrate toxins in their muscles or internal organs.

A venomous animal has toxins that it can inject into a wound to hurt or kill another animal. Some snakes can inject venom with special fangs, but some amphibians have pointed ribs that are sharp enough to stab a potential predator. The ribs will project through the amphibian’s sides through tiny spots that are filled with toxins. The toxins coat the points of the ribs, and if the predator tries to bite down, it gets those toxins stabbed right into its mouth. Some fish have spines that are coated in toxins, and of course many insects, arachnids, and other invertebrates have stingers that inject toxins.

Generally, a poisonous animal absorbs toxins from a food it eats, often a toxic insect, and instead of getting sick, it uses those toxins to protect it from predators. A venomous animal usually produces its own toxins in its body, especially animals that use venom to kill or disable prey. It costs energy for the animal to make venom, and it doesn’t want to waste it. That’s why snakes will sometimes give what are called dry bites in self-defense, where it bites but doesn’t inject any venom. It’s hoping that the pain of the bite itself will make a potential predator retreat without the snake needing to use venom.

Different toxins have different effects, naturally, and animals produce so many different kinds of toxins that we could talk about it all day and not even cover them all. Instead, let’s quickly discuss two animals, one venomous and one poisonous.

Our venomous example is the king cobra. It can grow over 18 feet long, or 5.5 meters, and lives in southern Asia. It mostly eats other snakes and some lizards. Its venom contains numerous toxins that do different horrible things. The neurotoxins in its venom affect the central nervous system, which can cause all sorts of issues like dizziness, pain, blurred vision, sleepiness, and even paralysis. Other toxins in the venom are called cardiotoxic because they affect the heart, making it weak so that circulation of blood slows down. If a king cobra bites you and injects venom, you can die within 30 minutes as the venom basically just shuts your body down, one process at a time. If your heart stops or your diaphragm becomes paralyzed so you can’t breathe, that’s it for you. Fortunately, in ordinary situations the king cobra is shy and avoids people, so if you don’t bother it, it won’t bite you.

Our poisonous example is the pufferfish. Some species of pufferfish are incredibly poisonous. You may have heard about fugu, which is considered a delicacy even though it’s so poisonous that in Japan and some other countries, chefs have to be specially trained and licensed to prepare the fish to eat. The part of the fish that’s considered tastiest is also the part that’s most poisonous, the liver. It contains tetrodotoxin, which is a neurotoxin that stops your nerves from sending the tiny electrical signals that allow them to move. If you’re poisoned with tetrodotoxin, you start to feel dizzy and sick, then you start having difficulty speaking and moving, then you have trouble breathing, and then, ultimately, you’re paralyzed and can’t breathe, at which point you die. Since the toxin doesn’t affect your brain, you remain completely aware of what’s happening to you but there’s nothing you can do about it. There’s no antidote. Fortunately, you have the option of not eating fugu. Also, it turns out that the pufferfish’s poison comes from a type of bacteria, so fish raised in careful conditions in captivity aren’t poisonous.

Most poisonous and venomous animals are harmless to humans!

Next, Connor wrote and said, “I recently moved to Michigan from West Virginia and noticed a lot of black squirrels around. Are they a different species/sub-species or just melanistic individuals?”

I looked into this and sure enough, Michigan and other areas around the Great Lakes are known for a large population of black squirrels. I’ve never seen a black squirrel but now that I’ve looked at pictures of them, they are awesome and I wish I had some in my yard.

The eastern gray squirrel is the most common species of squirrel in eastern North America, and a black morph of that species and other squirrel species is not that unusual. The color difference is due to a small mutation in the gene that controls how much pigment the squirrel’s fur contains. Connor is right that the coloration is due to melanistic individuals.

But that doesn’t explain why there are so many black squirrels in Michigan and surrounding areas. No one’s completely sure why that is. In other animals, including the gray wolf and the leopard, melanistic individuals are more common in areas where there’s thick vegetation that blocks a lot of sunlight. A dark-colored wolf or leopard is better camouflaged in the shadows, which allows it to sneak up on prey. But the squirrel isn’t a predator, and black squirrels don’t seem to be any more common in heavily forested areas compared to more park-like areas.

One suggestion is that black squirrels find it easier to stay warm in cold weather, because dark fur absorbs more heat than gray fur. This actually does seem to have some basis in fact. Black squirrels are much more common in northern areas, including parts of Canada where the eastern gray squirrel ordinarily doesn’t live. Black squirrels are correspondingly rare in more southern areas where winters are mild, which explains why I’ve never seen one. Then again, the fox squirrel is also common in eastern North America, often living in the same areas where eastern gray squirrels live, and they also have a black morph, but black fox squirrels mostly live in the southeast. So it’s a mystery.

Black squirrels are the same as ordinary colored squirrels. They just look different. That reminds me that I have an episode about squirrels planned for some time later this year, especially unusual squirrels.

Next, Anna has a question about dogs. She says, “We have a dog named Sadie, who is a beagle mix. She is much more aware of the sounds and smells around us and often howls and barks at things that we can’t see. How do dogs have such a strong sense of smell and good hearing?”

The wild ancestors of dogs were wolves. Wolves are generally nocturnal, and as a result, dogs have sensitive hearing and smell to find prey when it’s dark. A dog can hear in the ultrasonic range, which refers to sounds higher than human hearing. Humans can hear sounds up to 20,000 hertz, while dogs can hear sounds up to 50,000 hertz. A dog also has a lot of muscles in its ears that allow it to turn its outer ear to find sounds. While some dog breeds have lapped-over ears, wolves and many dog breeds have pricked-up ears that act as little satellite dishes to gather up as many sounds as possible. If you cup your hands behind your ears, you can get a sense of how this helps. A dog also has a relatively large ear canal, which is the inside part of the ear. A large ear canal allows more sound vibrations in. Cats actually have even better hearing than dogs, but cats don’t have nearly the same ability to smell.

A dog’s sense of smell is incredible. Humans have about six million olfactory receptors in our noses. That sounds like a lot, but a dog has over 200 million olfactory receptors! It can also process all those smells incredibly well in its brain, so that with training a dog can detect unbelievably faint smells. That’s why dogs are used to sniff out dangerous items like bombs and illegal drugs, or find people who are buried in rubble after an earthquake or other disaster, or track down people who are lost. Dogs can even learn to detect the smell of some diseases, including cancer, malaria, and tuberculosis.

A dog’s nose is much different from a human nose. If you have a dog, or can borrow a friend’s dog, sit down and take a look at their nose. Ha ha, the dog just licked you in the face! That’s hilarious! The dog’s nose has nostrils in the front but if you look carefully, you’ll see that the nostril openings continue along the sides of its nose, in a little slit. There’s also a little fold of tissue inside the nose. The tissue separates the air into two streams. One stream goes into the lungs, but the other gets circulated into the nose to come in contact with all those olfactory receptors. Then, when the dog breathes out, the air goes out the side slits instead of out the main nostrils, so it doesn’t push any odors out of the nose. A dog’s nose works best when it’s damp, which is why a healthy dog has a wet nose.

When you hear a sound, you can usually tell which direction it’s coming from by turning your head, because the sound will be slightly louder in one ear than the other and your brain can make sense of this difference. Dogs can tell which direction a smell is coming from because its brain can tell which nostril is picking up more of the smell.

A dog’s sense of smell is so acute, and so important to the animal, that a dog that loses its vision can often do just fine. It can smell its way around. Naturally, some dog breeds have a better sense of smell than others, and some individuals are better at smelling than others too.

Don’t feel bad about your sense of smell, though. Humans may not be as good at smelling as dogs are, but we can train ourselves to be more sensitive to faint odors. The next time you take a walk, pay attention to what you’re smelling and I bet you’ll notice a lot more scents than you realize.

Next, Helenka also wanted to know about my writing. Thank you so much for asking! Now I can plug my books and also tell you how the strange animals podcast book is coming along!

I mostly write fantasy fiction. I have a steampunk adventure book available called Skytown, and a related collection of short stories about the same characters from the book, which is called Skyway. Sometimes I get the titles confused because they’re really similar, but Skytown is called that because there’s a city in the book that can only be reached by air, which in this fantasy world is mostly airships. The main characters are two young women named Jo and Lizzy, friends who are airship pirates. It’s a lot of fun, and the short story collection actually tells how Jo and Lizzy met and what they did together right up to the start of the novel. If that sounds interesting, I’d love it if you could pick up a copy of one or both books. They’re published by small independent publishers, who don’t make a lot of money and have trouble getting books into physical stores. There’s a link in the show notes.

Okay, so now I get to tell you all about the Strange Animals Podcast book! I’ve been working on it all year and it’s getting really close to being done. The title is Beyond Bigfoot and Nessie: Lesser-Known Mystery Animals from Around the World, and most of the material is taken directly from mystery animal episodes from the last four-plus years, BUT I’ve made sure to update the chapters as much as possible and I’ve added some new chapters.

I’ve decided to self-publish the book, so I’m planning a Kickstarter to cover the costs of hiring a cover artist and things like that. I’d like to run the Kickstarter in October, which would give me time to get it published hopefully in time for the holidays in case people want to order copies to give as gifts. We’ll see how that goes, though. There’s a ton of work that goes into running a successful Kickstarter, and although I don’t need a whole lot of funding for the book, it still worries me that maybe no one will be interested and it won’t meet its funding goal and I’ll have to pay for everything out of pocket. I’m already kind of broke this year from paying about $5,000 to the emergency vet to save my cat Poe’s life, but honestly, if the choice is between having Poe running around and playing or self-publishing a book, I will choose Poe every single time.

Anyway, one way or another I’ll make sure the Beyond Bigfoot and Nessie book is available to buy before the podcast’s fifth year anniversary in February 2022!

Finally, this wasn’t sent in as a question but I thought it would be a nice way to finish off the episode. In a really nice review, a listener who I think is named Meg said “I think she’s southern like me but not sure.” Yes, I am southern, although I don’t have much of an accent. I was born in Georgia and grew up in East Tennessee, where I live now.

Thanks to everyone who sent in questions! We’ll probably have another Q&A episode eventually, maybe next year, so feel free to send me your questions! I think I got everyone’s questions answered this time, but if I missed yours, definitely let me know. The best way to get in touch with me is through email, strangeanimalspodcast@gmail.com.

To finish us off, Richard from NC wanted me to play the Axolotl song. I won’t play the whole thing, because it’s kind of long, but here’s a clip and there’s a link in the show notes. It’s by an animator and musician called Joel Veitch. I’ve had this song stuck in my head ever since Richard sent me the link, so now you will too. Also, I promise I’ll make a whole episode about the axolotl soon.

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!