Monthly Archives: March 2025

Episode 426 Lots of Little Birds

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Thanks to Murilo, Alexandra, and Joel for their suggestions this week!

The bird sounds in this episode come from xeno-canto, a great resource for lots of animal sounds!

A cactus wren [picture by Mike & Chris – Cactus WrenUploaded by snowmanradio, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=15876953]:

The sultan tit [photo by By Dibyendu Ash – CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=72070998]:

A female scarlet tanager [photo by Félix Uribe, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=81340425]. The male is red with black wings:

The Northern cardinal:

The yellow grosbeak [photo by Arjan Haverkamp – originally posted to Flickr as 2008-08-23-15h00m37.IMG_4747l, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=9596644]:

The purple martin isn’t actually purple [photo by JJ Cadiz, Cajay – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=4255626]:

The dusky thrush [photo by Jerry Gunner from Lincoln, UK Uploaded by snowmanradio, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=20762838]:

The European rose chafer, not a bird [photo by I, Chrumps, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2521547]:

Show transcript:

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

This week we’re going to learn about a lot of little birds that deserve more attention, because they’re cute and interesting. Thanks to Murilo, Alexandra, and Joel for their little bird suggestions!

All the birds we’ll talk about today are called passerines, because they belong to the order Passeriformes. They’re also sometimes referred to as perching birds or songbirds, even though not all passerines sing. Passerines are common throughout the world, with more than 6,500 species identified. I’ve seen about 150 of those species, so clearly I need to work harder as a birdwatcher.

Passerines are referred to as perching birds because of their feet. A passerine bird has three toes that point forward and another toe pointing backwards, which allows it to wrap its toes securely around a twig or branch to sit. Its legs are also adapted so that the toes automatically curl up tight when the leg is bent. That’s why a sleeping bird doesn’t fall off its branch.

Let’s start with one of Murilo’s suggestions, the wren. Wrens are birds in the family Troglodytidae, and are usually very small with a short tail, a pointy bill that turns slightly downward at the tip, and brown plumage. It mainly eats insects and larvae that it finds in nooks and crannies of trees, and many species will investigate dark places like hollow logs, the openings to caves, or your apartment if you leave the back door open on a warm day. Many sing beautiful songs and have very loud voices for such little bitty birds.

Most wrens are native to the Americas, including the canyon wren that’s native to western North America in desert areas. It’s cinnamon-brown with a white throat and an especially long bill, which it uses to find insects in rock crevices. It lives in canyons and has a more flattened skull than other wrens, which means it can get its head into crevices without hurting itself. No one has ever seen a canyon wren drink water, and scientists think it probably gets all the water it needs from the insects it eats. Where do the insects get the water they need? That’s an episode for another day.

This is what a canyon wren sounds like:

[bird sound]

Not every bird that’s called a wren is actually in the family Troglodytidae. Some just resemble wrens, like an unusual bird that Murilo brought to my attention. It’s called Lyall’s wren but it’s actually in the family Acanthisittidae, and it was once widespread throughout New Zealand. By the time it was scientifically identified and described in 1894, it was restricted to a single island in Cook Strait.

Lyall’s wren was flightless, and only five passerines are flightless as far as we know. All five were island birds who have since gone extinct, which is unfortunately the case with Lyall’s wren too. It was greenish-brown with a yellow eye stripe and its tail was just a little short nub. We don’t know much about it because between 1894 when a lighthouse was built and some families moved to the island to work at the lighthouse, bringing their housecats, and 1925 when the feral cat colony on the island was finally killed off, all the remaining Lyall’s wrens were eaten by cats or killed by people to sell as museum specimens. To be clear, it’s entirely the fault of people that the bird went extinct, because they brought the cats to the island and let them run loose. The bird probably actually went extinct in 1895, just one year after cats were introduced to the island.

Murilo also suggested some little birds called chickadees and tits, which belong to the family Paridae. They’re very small, often brightly colored or with bright white markings, with short bills that help them crack seeds open. They also eat insects. They’re not found in South America or Australia, but they’re very common in North America, Eurasia, and most of sub-Saharan Africa. Many species love to visit bird feeders, and since they’re cute and active little birds, people are happy to have them around.

Some species in this family have crests, which makes them even cuter. The tufted titmouse, which is found in eastern North America, has a little tufted crest on its head, for instance. It’s a soft gray-blue in color with patches of rusty-red under its wings, and white underneath. The gray crested tit lives in western Europe and also has a fluffy crest on its head. It’s gray-brown with a thin black and white ring around its neck and a buff-colored underside. The yellow tit lives only in forests in central Taiwan and is a gorgeous dark blue with bright yellow underneath and on its face, with a darker crest. It’s so beautiful that it’s becoming rare, since people trap the birds to sell to disreputable collectors. The sultan tit is even more spectacular, if that’s possible, since the male is black with bright yellow underparts and a bright yellow crest. It lives in parts of south Asia and some subspecies have a black crest instead.

This is what a sultan tit sounds like:

[bird sound]

Another spectacular bird is one Alexandra suggested, the summer tanager. It’s a common summer visitor in the eastern and southwestern United States that winters in Central and northern South America. The male is a bright, cheerful red all over while the female is yellow. The western tanager is a close relation that lives in western North America, wintering in Mexico. The male has a mostly black back with a yellow rump and yellow underneath, with red and orange on his face. Females are yellowy-green and gray. The scarlet tanager is also similar, although the male is red with black wings and the female is yellowy-green and gray. They eat insects and fruit, and spend a lot of time in the very tops of trees.

This is what a scarlet tanager sounds like:

[bird sound]

Despite their names, all three of these tanagers aren’t actually tanagers. Tanagers are members of the family Thraupidae and are native to central and South America. Many of them are brightly colored and absolutely gorgeous, like the red-legged honeycreeper that’s common in Central and parts of South America. The male has a black back and tail and is bright blue on the rest of his body, except for a black mask over his eyes. His long curved bill is also black, but his legs are bright red. The female has red legs but she’s mostly greeny-yellow.

The North American tanagers are actually more closely related to the cardinal than to other tanagers, and are placed in the family Cardinalidae. The family is named after the northern cardinal, which is common throughout most of the United States and parts of Mexico. The male is bright red with black around his bill, while the female is more of a rosy brown color. Both have red bills and tufted crests. In North America, the cardinal appears on a lot of Christmas cards because its bright red plumage against a snowy background is so cheerful in winter.

This is what a northern cardinal sounds like:

[bird sound]

Alexandra also suggested the blue grosbeak, while Joel suggested the yellow grosbeak. Both are also members of the family Cardinalidae. The blue grosbeak lives in much of the United States in summer and spends the winter in Mexico and Central America. The male is blue with black and rufous markings and a silvery-gray beak, while the female is rufous-brown and gray. The yellow grosbeak lives along the Pacific slope of Mexico and may be the same as the golden grosbeak that lives in western South America, or a very close relation. Scientists aren’t sure yet. The male is a bright golden yellow with black and white wings and a black bill, while females are a less conspicuous green-yellow. The yellow grosbeak is larger than the blue but they’re both pretty big and robust. They eat insects and lots of other small animals like snails and spiders, along with fruit and seeds. Sometimes a yellow grosbeak will show up farther north, in the United States, and birdwatchers lose their minds with excitement.

This is what a yellow grosbeak sounds like:

[bird sound]

Joel also suggested the purple martin, a type of swallow that’s common throughout the Americas. It’s not purple but it is a dark blue-black color with iridescence that reflects light. This makes the bird look anywhere from dark purple to blue depending on the angle of the light. The male is much darker than the female, who is more gray-blue in color. It spends the summer in North America, raising babies and eating lots of insects, then migrates to South America to spend the winter.

This is what a purple martin sounds like:

[bird sound]

Another Joel suggestion is the dusky thrush, which is another passerine that migrates a long distance. It spends the summer in Siberia and nearby areas to nest, then flies south to spend the winter in southern China, Japan, India, Vietnam, Korea, and other nearby areas. It’s mostly brown on its back and white underneath with lots of speckles, and a light stripe over its eye. Males and females look very similar. It eats insects, spiders, worms, seeds, and berries and spends a lot of its time on the ground. Every so often a dusky thrush will get lost during migration and end up in western Europe or Alaska, and again, birdwatchers in those areas go nuts trying to catch a glimpse of it.

This is what a dusky thrush sounds like:

[bird sound]

Let’s finish this episode with another of Joel’s suggestions, the European rose chafer. You may be wondering what kind of bird this is, and that is exactly what I was wondering. It sounds very pretty! Then I looked it up, and it’s not a bird at all, it’s a type of beetle!

The rose chafer is a big metallic-green beetle related to scarabs that grows up to 20 mm long. It’s common in Europe and some parts of southeast Asia, and is often found on rose bushes in summer. It eats flowers, including the petals, nectar, and pollen, and really likes roses.

The female rose chafer lays her eggs in the ground and the larvae eat decaying vegetation. There’s also a related beetle called the rose chafer that lives in parts of North America, but it’s sort of a muddy tan color, and while it likes to eat roses and other flowers, it also likes to eat fruit like peaches and grapes. Its larvae eat roots and can damage plants.

Since the European rose chafer is such attractive beetle, with an iridescent bronze shimmer to its emerald-green carapace, you’d think people who grow roses would like to have them on their rose bushes, but this isn’t actually the case. I guess people who grow roses want to see the roses without them being all chewed up by beetles. To bring it back to birds, birds don’t eat the rose chafer because the beetle contains toxins that make it taste awful. But they’re still really pretty.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 425 Rabbits!

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Thanks to Alyx and Richard from NC for their suggestions this week! Let’s learn about rabbits!

Further reading:

Why your pet rabbit is more docile than its wild relative

FOUND: Small enigmatic rabbit with black tail lost to science for more than 120 years rediscovered hopping around mountain range in Mexico

The Omiltemi cottontail rabbit, as caught on a camera trap [photo taken from second article linked above]:

Show transcript:

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

This week we’re going to talk about bunnies, and also learn about how a wild animal differs from its domesticated counterpart. Thanks to Alyx for suggesting this excellent topic. Thanks also to Richard from NC who alerted me to a rediscovered rabbit we’ll discuss too.

Thanks for all the well wishes in the last few weeks about my surgery. It went just fine and all I have now is a cool-looking new scar, although I was seriously hoarse for about a week. It’s pretty weather here in East Tennessee and officially it’s spring in the northern hemisphere, so let’s talk about some springtime bunnies!

Collectively rabbits and hares are called leporids after their family, Leporidae. Leporids are famous for hopping instead of walking, and they’re able to do so because their hind legs are longer than their front legs and have specialized ankle joints. Ancestors of leporids developed this ankle as much as 53 million years ago, but their legs were much shorter so they probably ran instead of hopped. Hares have longer legs than rabbits and can run faster as a result, but both rabbits and hares are known for their ability to bound at high speeds. When a rabbit or hare runs, it pushes off from the ground with the tips of its long hind toes, and its toes are connected with webbed skin so they can’t spread apart. If the toes did spread apart, they would be more likely to get injured. Rabbits and hares also don’t have paw pads like dogs and cats do. The bottom of its foot is covered with dense, coarse fur that protects the toes from injury. Its long claws help it get a good purchase on the ground so its feet won’t slip.

Leporids eat plants, including grass, weeds, twigs, and bark. Animals that eat grass and other tough plants have specialized digestive systems so they can extract as many nutrients from the plants as possible. Many animals swallow the plants, digest them for a while, then bring up cuds of plants and water to chew more thoroughly. Rabbits and hares don’t chew their cud in that way, but they do have a system that allows them to twice-digest the plants they eat.

After a leporid eats some plants, the plant pieces go into the stomach, naturally, and then travel into the first part of the large intestine, called the cecum. The cecum separates the softer parts of the plants from the harder, less digestible parts. The hard parts are compressed into hard pellets that the rabbit poops out. But the soft parts of the plants, which are most nutritious, develop into softer pellets. These are called cecotropes, and as soon as the rabbit poops out the cecotropes, it immediately eats them again. This allows the digestive system to get a second round to extract more nutrients from the plants.

Hares aren’t domesticated, but rabbits have probably been domesticated many times in different places over the last several thousand years, first for food and fur, and then as pets. The domesticated rabbit we have today is descended from the European rabbit, also called the cony. If other species of rabbit were ever domesticated, we don’t have record of it. The rabbit has also been introduced into the wild in places it has no business to be, like Australia, where it’s an invasive species. You know where else the European rabbit has been introduced? The British Isles. It’s native to mainland Europe, not England, Scotland, Ireland, Wales, and smaller islands nearby. Historians think the rabbit was introduced to England soon after the year 1066, but it got really common a few hundred years later.

We discussed domestication way back in episode 106, mostly in relation to dogs. An interesting thing happens with domestication. Certain physical traits come along with the behavioral traits of reduced aggression and willingness to treat humans as surrogate parents. In the case of dogs, these often include a puppy-like appearance, including floppy ears, curled tail, smaller adult size, and a rounder head with smaller jaws. White patches of fur start to show up too.

This is true in rabbits as well as dogs. Because humans wanted to breed rabbits that weren’t scared of people, domesticated rabbits are less anxious and aggressive in general than their wild counterparts. When traits like white patches, lop ears, and a more rounded face appeared in the domesticated population, people would keep those rabbits to breed because they’re extra cute, which has led to over three hundred different breeds recognized today by rabbit enthusiasts.

Because domesticated rabbits are calmer and more trusting than wild rabbits, they can’t survive long in the wild. A domesticated rabbit doesn’t know how to escape from predators or avoid cars, and it’s not used to cold weather. If you decide to adopt a bunny, make sure you do research ahead of time to know what to expect, and as with most animals it’s best to adopt two so they won’t be lonely. Rabbits are social animals and need a rabbit friend. There are even pet rescues that specialize in rabbits who need homes.

We talked about giant rabbits in episode 115, and the tiny volcano rabbit in episode 356, so let’s finish this episode with a medium-sized rabbit called the Omiltemi cottontail. Cottontail rabbits are native to the Americas and most have fluffy white fur on the underside of their tails. The Omiltemi cottontail doesn’t have any white fur at all, and is reddish-brown and black in color with some lighter gray on its face. It’s large for a wild rabbit, about 18 inches long, or 45 cm, although it’s actually smaller than other rabbits that live in the area. It lives only in Mexico, specifically in a single part of the Sierra Madre del Sur mountain range, in what is now the Omiltemi Ecological State Park.

It was first described in 1904 and then reportedly wasn’t seen again, although the local people knew all about it. Even though it lives in a protected area, poaching is still a big problem. When an expedition to find the rabbit got underway in 2019, local hunters provided pelts to the scientists when they asked about the rabbit, since they didn’t know they weren’t supposed to kill the local rabbits. They certainly didn’t know they had an incredibly rare species of rabbit living in their back yards.

The team used camera traps, drone surveys, and the knowledge of local people to find and identify the Omiltemi cottontail. It turns out that the rabbit is mostly nocturnal and prefers higher elevations, which made it harder to find. We still don’t know how many there are left, but now that scientists are certain that it’s not extinct, it can be better protected.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 424 Old-Timey Giant Snakes

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Show transcript:

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

Recently I read about a giant snake supposedly seen in Tennessee in 1908. The story seemed a little suspicious so I dug into it, and it got a lot more complicated than I expected.

On July 25, 1908, the St. Louis (Missouri) Globe-Democrat ran an article about a giant snake in Loudon, Tennessee. Loudon is a town half an hour’s drive away from Knoxville in East Tennessee, although it took longer to get there from Knoxville in 1908. According to the article, the snake was “at least twenty-five feet in length, eight inches in diameter and twenty-four inches in circumference.”

The longest snake ever reliably measured is a reticulated python named Medusa, who was measured as 25 feet 2 inches long in 2011, or 7.67 meters. Medusa holds the world record for the longest snake in captivity. Reticulated pythons are constrictors, which are non-venomous snakes who kill their prey by squeezing them until blood flow is shut off to the organs, causing cardiac arrest and death. As a result, they’re incredibly strong snakes. The reticulated python is native to southern Asia and not likely to be found running loose in East Tennessee even today, and certainly not in 1908.

The famous Boa constrictor and other snakes in the genus Boa are all native to Central and South America, while the closely related anaconda is from tropical South America. These snakes are also constrictors.

The anaconda is rumored to grow over 30 feet long, or 9 meters, although the longest specimen ever reliably measured was 17 feet long, or 5.2 meters. Since snake skin is stretchy, though, preserved skins of huge size are often provided as proof of snakes much longer than the known maximum. While the anaconda isn’t as long as the reticulated python, it’s much bulkier, so a 25-foot anaconda would be much heavier and larger around than a 25-foot reticulated python.

The 1908 article claims that the snake “has been seen off and on for the last twenty-eight years, but not until this summer has it caused any serious alarm.” I don’t know about you, but even as someone who likes animals and thinks snakes are neat, if I saw a 25-foot snake I would be a little bit alarmed even if it wasn’t doing anything. The article then describes how the snake had knocked down a fence while climbing over it and that it had taken a lamb. One man even managed to shoot the snake, although only with “small shot,” and the article claims that the snake, “in a frenzy from the pain, tore up saplings in getting away.”

The article finishes by reporting that women and children were barricaded in their homes while men organized a posse to hunt down the giant snake, which was rumored to live in a cave overlooking the river.

The same article ran in various newspapers around the country for months, but there was no follow-up to let readers know if the snake had been found. But the story didn’t appear in any Tennessee newspapers.

The only 1908 article about a giant snake in Tennessee that appears in a Tennessee newspaper is from August 21. The Chattanooga, Tennessee Daily Times reported that a blacksnake “fully six feet long and two inches in diameter” had been spotted eating young pigeons above the Birmingham railway station. A police officer shot and killed it, but its body couldn’t be recovered from the steep hillside above the tunnel.

“Blacksnake” is a term used for two snakes that are common throughout the southern United States: the eastern black kingsnake and the North American racer. Both are black in color and can grow more than 6 feet long, or 1.8 meters. Both are non-venomous and eat small animals like mice, frogs, and lizards, while the kingsnake also sometimes eats other snakes.

The longest snake found in Tennessee, which also lives throughout much of eastern North America, is the gray ratsnake, which is frequently 6 feet long and sometimes longer. One unverified report of a captive snake 8 feet 10 inches long, or almost 2.5 meters, comes from Tennessee. It’s a mixture of dark and light gray with a lighter belly. It’s non-venomous and is actually a constrictor, although it’s not dangerous to humans. If it feels threatened, it will sometimes pretend to strike and rattle the tip of its tail against dead leaves or whatever else might be underneath it, which produces a buzzing sound that mimics a rattlesnake’s rattle. You’re not fooling anyone, gray ratsnake.

The eastern racer will also vibrate its tail against leaves to imitate a rattlesnake’s rattle, but the eastern racer is such a fast-moving snake that it doesn’t usually need to convince potential predators it’s dangerous. It just runs away. Despite its name of Coluber constrictor, it’s not actually a constrictor, although it will pin an animal to the ground with its body until it can swallow it whole. It and the gray ratsnake can both climb trees and will eat bird eggs and young birds when they find them.

There is another article about a giant snake in a Tennessee newspaper from 1908. The Chattanooga Star reported on August 20 that a 12-foot, or 3.6 meter, rattlesnake was attacked by a boar when it tried to enter a hog pen. The farmer managed to shoot the snake, which had 29 rattles. The snake was referred to as “Big Jim” in the area. But that story was supposed to have happened in Sullivan, Indiana, not in Tennessee.

But Indiana newspapers don’t run this account. A July 22, 1908 article in the Indianapolis News reports that a rattlesnake with 26 rattles was killed in Nashville, Indiana, but that snake was not quite six feet long, or 1.8 meters.

The “Big Jim” account does appear in one Indiana newspaper, the Hamilton County Times from August 21, 1908. But that article is headlined “Some Hoosier ‘Nature Fakes’” and says Big Jim was first spotted in the neighboring state of Illinois but had been discovered attacking a farmer’s chickens in Sullivan County, Indiana. This must be the same as Sullivan, Indiana reported in the Tennessee paper. But Big Jim was only ten feet long in the Indiana story, or 3 meters, and wasn’t killed. The article says the local farmers were organizing to hunt it down, but then goes on to talk about some other stories of huge snakes and a giant fish. It seems clear that the Indiana article is meant to be amusing, not factual.

The largest rattlesnake species is the eastern diamondback rattler, and the largest one ever reliably measured was 7.8 feet long, or 2.4 meters. That’s big, but it’s not Big Jim big. The eastern diamondback also doesn’t live anywhere near Indiana or Illinois. It’s native to the southeastern United States, especially along the coast.

Newspaper reporters weren’t always scrupulous in the olden days, sometimes making up stories to fill space and entertain the reader. Stories of huge snakes are so common in old newspaper reports that the term “snake story” was once used interchangeably with “fish story” to indicate an animal of improbable size that was supposedly spotted or killed, but without any proof.

In 1935, the Statesville (North Carolina) Record and Landmark ran an article titled “Giant Snake Story Proves To Be Hoax.” No kidding! In this case, though, the story was about a snake skin 16 feet long, or nearly 5 meters, which was supposed to be from a rattlesnake killed in a local swamp. The article revealed that the two men who claimed to have shot the rattlesnake had later confessed the skin was from a python, and had been sent to one of the men by a relative in South America. At least that one was from a real snake.

Thanks for your support, and thanks for listening!

Episode 423: Pack Rats and Busy Mice

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Further reading:

Mouse filmed moving items in man’s shed in Bristol

The pack rat:

Show transcript:

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

This week I’m sharing a Patreon episode from last year because I have surgery scheduled. Don’t worry, it’s minor thyroid surgery and I’ll be fine, but my doctor said that a side effect might be hoarseness while I recover. Rather than risk sounding like an old frog, and to allow myself lots of time to rest afterwards, I’ve scheduled Patreon episodes for this week and next week.

At the beginning of this year, in early January 2024, you may have heard about a man in Wales who had an interesting visitor to his work shed. Rodney Holbrook is 75 years old and a retired postal worker, and at the end of 2023 he started noticing something weird. Things in his work shed kept being moved, and not in a way that suggested another person was getting in.

Initially Rodney noticed that some bird food had been moved into an old pair of shoes. This wasn’t just a one-time thing that would suggest an accident, like maybe Rodney had absent-mindedly decided to store the bird food in his shoes, or maybe it just fell there. The bird food kept ending up in the shoes.

Other things kept getting moved too. Small items that Rodney had left out while making and repairing things at his work bench kept getting put into a box, like tools and nuts and bolts. It happened almost every night.

Fortunately, Rodney is also a wildlife photographer, and he just happened to have a night vision camera. He set it up in the shed to find out what on earth was going on.

A mouse was going on, that’s what was going on. This actually wasn’t a huge surprise to Rodney, because years before, in 2019, a friend of his had had the same thing happen.

His friend was Steve Mckears who lived near Bristol, England. Steve kept crushed peanuts in a tub to use as bird food, but he started to notice other things mixed in with the peanuts. First it was just one screw, then it was lots more things that he’d left around his shed. He couldn’t figure out a solution, because he always locked his shed at night.

As Steve said at the time, “I was worried. I’m 72 and you hear of things going wrong with 72-year-old gentlemen in the mind.” Fortunately, Steve’s friend Rodney set up a camera and proved that there was nothing wrong with Steve’s mind or with the shed’s lock. It was just a mouse who was tidying up.

The question is why are these mice tidying up someone else’s shed? Don’t the mice have sheds of their own to clean up? It’s probable that the mice are actually living in the sheds and are wondering why some humans keep barging in every day and making a mess.

Rodents of all kinds do tend to tidy up as part of the foraging and nesting process. Sometimes that means moving debris so the animal can find important items more easily, sometimes it means bringing items back to its nest. House mice and rats will steal small items from humans to make nests, like socks and facecloths. Some rodents are attracted to shiny things and will stash them away or even bury them.

One animal, the pack rat, is so famous for storing items that we call a person who likes to collect things a pack rat. The pack rat lives throughout much of North and Central America and is related to mice and rats. It’s bigger than a mouse but smaller than most rats, and some species have furry tails like ground squirrels. It builds a den out of whatever materials are available where it lives, and its den is complex and usually well hidden. Desert species like to build under a cactus, while others live in cliffs or among rocks, in abandoned buildings or sometimes non-abandoned buildings, under bushes, in the tops of trees, or even in the entrances to caves. The den can be quite large and contains numerous rooms used for food storage, sleeping, and storing all the interesting things the pack rat finds while foraging.

A pack rat constructs a debris pile to hide its den, referred to as a midden. “Midden” is an old-fashioned word used to describe a place where household waste used to be thrown. Archaeologists love middens because you can learn a lot about people by the things they throw away, and other scientists love pack rat middens for the same reason. Some pack rat middens have been discovered preserved for 50,000 years, which has allowed scientists to learn a lot about what plants were growing in the area at the time. Since the middens also contain the pack rat’s fecal pellets, the scientists can also learn a lot about what the rat was eating, how big it was, and so forth.

Pack rats especially like shiny objects and will steal from people. In 2017 when historians were restoring an old home in Charleston, South Carolina dating back to 1808, they discovered several old pack rat middens in the walls of the kitchen. The middens contained buttons, marbles, sewing pins, and even some scraps of paper, including bits of newspaper with a readable date from November 1833. But some of the other bits of paper were torn from a writing primer, a book for people learning how to read or write. That’s not much of a surprise until you remember that this was the early 19th century, that the house was owned by a slave trader, and that the kitchen in particular would have been staffed by enslaved people, who were not supposed to learn how to read. Thanks to the pack rats, we know that at least one person was secretly learning how to read and write. I just hope the rats didn’t do too much damage to their book.

The pack rat is also sometimes called a trader rat, because it can only carry one thing at a time. If it’s carrying an acorn home and it chances upon a shiny gold ring, it will drop the acorn and carry the ring home. But you wanted an acorn, didn’t you, instead of that ring?

As for mice tidying up, we don’t really know why they do it, but it’s probably actually quite common. It just happens at night when people aren’t around, and in the morning they don’t know why all the nails have been moved into the box of nails, but hey, isn’t that handy? It reminds me of the stories of little house spirits called brownies, which were supposed to work at night cleaning and tidying. When the family woke up the next morning, the house or workshop was, ahem, squeaky clean, and all the family had to do was leave out a little cake or cream every night for the brownie.

Thanks for your support, and thanks for listening!

Episode 422: Two Tiny, Tiny Animals

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Thanks to Tim and Mia who suggested one of this week’s animals!

Further reading:

Genomic insights into the evolutionary origin of Myxozoa within Cnidaria

A tardigrade, photo taken with an electron microscope because these little guys are incredibly tiny:

Show transcript:

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

This week we’re going to talk about two microscopic or almost microscopic animals, one suggested by Mia and Tim, the other one I just learned about myself.

We’ll start with Mia and Tim’s suggestion, the water bear, also known as the tardigrade. We’ve talked about it before but there’s always more to learn about an animal.

The water bear isn’t a bear at all but a tiny eight-legged animal that barely ever grows larger than 1.5 millimeters. Some species are microscopic. There are about 1,300 known species of water bear and they all look pretty similar. It looks for all the world like a plump eight-legged stuffed animal made out of couch upholstery. It uses six of its fat little legs for walking and the hind two to cling to the moss and other plant material where it lives. Each leg has four to eight long hooked claws. It has a tubular mouth that looks a little like a pig’s snout.

An extremophile is an organism adapted to live in a particular environment that’s considered extreme, like undersea volcanic vents or inside rocks deep below the ocean floor. Tardigrades aren’t technically extremophiles, but they are incredibly tough. Researchers have found tardigrades in environments such as the gloppy ooze at the bottom of the ocean and the icy peaks of the Himalayas. It can survive massive amounts of radiation, dehydration for up to five years, pressures even more intense than at the bottom of the Mariana Trench, temperatures as low as -450 Fahrenheit, or -270 Celsius, heat up to 300 degrees Fahrenheit, or 150 Celsius, and even outer space. It’s survived on Earth for at least half a billion years. Mostly, though, it just lives in moss.

Not every tardigrade is able to do everything we just talked about. They’re tough, but they’re not invulnerable, and different species of tardigrade are good at withstanding different extreme environments. Many species can withstand incredible heat, but only for half an hour or less. Long-term temperature increases, even if only a little warmer than what it’s used to, can cause the tardigrade to die.

Most species of tardigrade eat plant material or bacteria, but a few eat smaller species of tardigrade. It has no lungs since it just absorbs air directly into its body by gas exchange. It has a teeny brain, teeny eyes, and teeny sensory bristles on its body. Its legs have no joints. Its tubular mouth contains tube-like structures called stylets that are secreted from glands on either side of the mouth. Every time the tardigrade molts its cuticle, or body covering, it loses the stylets too and has to regrow them. In some species, the only time the tardigrade poops is when it molts. The poop is left behind in the molted cuticle.

The tardigrade’s success is largely due to its ability to suspend its metabolism, during which time the water in its body is replaced with a type of protein that protects its cells from damage. It retracts its legs and rearranges its internal organs so it can curl up into a teeny barrel shape, at which point it’s called a tun. It needs a moist environment, and if its environment dries out too much, the water bear will automatically go into this suspended state, called cryptobiosis.

Tests in 2007 and 2011 that exposed tardigrades to outer space led to some speculation that tardigrades might actually be from outer space, and that they, or organisms that gave rise to them, might have hitched a ride on a comet or some other heavenly body and ended up on earth. But this isn’t actually the case, since genetic studies show that tardigrades fit neatly into what we know of animal development and evolution. In other words, tardigrades are weird, but they’re Earth weird.

Our other tiny animal today is one that lacks pretty much everything animals usually have. Myxozoa are parasites that can’t live outside of the host’s body, a condition called obligate parasitism. They’re found in both freshwater and ocean water animals but evolved from an animal similar to a jellyfish that would have just swum around happily in the ocean. Now they’re microscopic parasites with the smallest genomes of any animals studied. Most only measure 300 micrometers at most, or 1/3 of a millimeter, although the largest known grows a humongous 2 mm long.

Different myxozoa have different life cycles, some of them complex. Because they’re so small, we naturally don’t know that much about them, and there are undoubtedly a whole lot of species that haven’t been discovered by science. They’re so numerous, and so different from other animals, that they’ve been placed into their own subphylum, classified in the Phylum Cnidaria. Cnidarians include jellyfish, corals, sea anemones, and many other aquatic invertebrates that show radial symmetry–but not comb jellies which have their own phylum.

In general, this is how a myxozoan spreads to a new host. A myxozoan secretes tiny capsules called myxospores that contain polar filaments. The myxopores are eaten by worms, at which point the capsule opens and the polar filaments uncoil and attach to the worm’s gut, where it develops into a sporoplasm and eventually detaches from the worm. The sporoplasm floats around in the water until it touches a fish, especially a fish’s gills, at which point it digs into the fish’s body and continues to develop.

When scientists identified the first myxozoans, they were classified as protozoans, single-celled animals. Many protozoans are parasitic. But as genetic testing became more refined and easier to do, and some myxozoans had their DNA sequenced, it became obvious that they were something else. Scientists just weren’t sure what. Finally scientists realized that they were similar genetically to jellyfish and their close relations, although they estimate it’s been about 600 million years since they shared a common ancestor.

Many myxozoans no longer have genes that allow communication between cells, multicellular development, body coordination, or even respiration in some species. Most are only a few cells in size and the most complex cell is the one that contains what’s called a polar capsule. This probably developed from its ancestor’s nematocysts, which are the cells that sting you if you touch a jellyfish, which is why you should never touch a jellyfish no matter how pretty it is.

Most myxozoa infect fish, but they’ve also been discovered in other animals. This includes a few frogs, turtles, aquatic birds, and octopuses. But they’ve also been discovered in two mammals, both of them shrews. Even though we already know about more than 2,000 species of myxozoa, scientists think there are probably hundreds, if not thousands more, but no one’s noticed them yet because they’re so small.

If you remember the Dr. Seuss book Horton Hears a Who, consider that the Whos might have actually been tardigrades. But probably not myxozoa, which wouldn’t have been able to build a Who city.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!