Episode 369: Animals and Ultraviolet Light

Sorry to my Patreon subscribers, since this is mostly a rerun episode from April 2019. It’s a fun one, though!

The teensy pumpkin toadlet [photo by Diogo B. Provete – http://calphotos.berkeley.edu, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=6271494]:

The electromagnetic spectrum. Look how tiny the visible light spectrum is on this scale! [By NASA – https://science.nasa.gov/ems/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=97302056]:

Show transcript:

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

This was supposed to be the 2023 discoveries episode, but not only have I had a really busy week that’s kept me from finishing the research, I’m also coming down with a cold. My voice still sounds okay right now but considering how I feel, it’s not going to sound good for long, and I need to finish the March Patreon episode too! I decided to rerun a very old Patreon episode this week to allow me time to finish the March Patreon episode before my voice turns into an unintelligible croak. I did drop in some fresh audio to correct a mistake I made in the original episode and add some new information.

This is one of my favorite Patreon episodes and I hope you like it too. It’s about animals that can see ultraviolet light.

I was going to make this a frog news episode, but I started writing about a tiny frog from

Brazil called the pumpkin toadlet and the episode veered off in a very interesting direction. But let’s start with that frog.

It’s called the pumpkin toadlet because it’s an orangey-yellow color that is just about the same color as pureed pumpkin. It’s poisonous and lives in the forests of Brazil. During mating season, the pumpkin toadlet comes out during the day, walking around making little buzzing noises. Researchers assumed those were mating calls until they started studying how the pumpkin toadlet and its relations process sounds. It turns out that the pumpkin toadlet probably can’t even hear its own buzzing noise. But they did discover that the pumpkin toadlet fluoresces brightly under UV light.

We’ve talked about this phenomenon before, back in the Patreon episode about animals that glow. Quite a lot of frogs turn out to fluoresce in ultraviolet light, which is a component of daylight. That explains why the pumpkin toadlet comes out during the day in mating season. It wants to be seen by potential mates. It’s actually the frog’s bones that fluoresce, but since it has very thin skin without dark pigment cells, the ultraviolet light can light up the bones.

I wanted to make sure I gave everyone the correct information about ultraviolet light, so I started researching it…and that led me down this rabbit hole. What animals can see in ultraviolet light? Can any humans see ultraviolet light? What does it look like?

Light is made up of waves of varying lengths. The retina at the back of your eyeball contains two types of cells, rods and cones, which are named for their shapes. Rods are for low-light vision and cones are for detail and color vision.

Humans have more cones than rods because we’re diurnal animals, meaning we’re most active during the day. Animals that are mostly nocturnal have more rods than cones, which help them see in low light although they don’t see color as well or sometimes at all as a result.

Most humans can see any color that’s a mixture of red, green, and blue, since we have three types of cone cells that react to wavelengths roughly equivalent to those three colors. Some people have what’s called red-green color blindness, which means either the person doesn’t have cones that sense the color red or cones that sense the color green. Various shades of green and red look alike for these people. Red-green color blindness is much more common in men than in women, with as many as 8% of men having the condition. A lot of times they don’t even know it. When I did my student teaching in a first grade class, one day I prepared a math lesson for the students that involved them sorting a little cup of candy into colors, and after they did the math problems associated with the different colors, they got to eat the candy. One little boy kept sorting certain colors of Skittles into the same column, and when I asked him, he didn’t realize they were different colors. They looked the same to him. So that day I learned to be careful about what kind of candy I used for sorting lessons, and he learned that he had red-green color blindness. My own dad was color blind too. It’s pretty common. Occasionally a person is born without the ability to see colors at all, but that’s extremely rare.

The visible light spectrum, also sometimes called the color spectrum, runs from violet to red. Just below violet is the wavelength referred to as ultraviolet. Many insects and birds can see ultraviolet, but typically an animal that can see ultraviolet can’t see infrared, which is the wavelength of light just past red. Birds that can see ultraviolet can usually see red, but not infrared.

In the original Patreon episode, this is where I said that humans can see ultraviolet light a little, but I was actually wrong. I thought blacklights worked by allowing us to see ultraviolet light, but that’s not the case. Blacklights are lamps that emit mostly ultraviolet light, but we only see a dark purple or blue that the blacklight’s filter allows through. While very few humans can see anything but the purple or blue, insects can see ultraviolet light and are attracted to it. That’s why bug zappers include blacklights. People also like blacklights because the ultraviolet light makes some things glow, which is fun to play with. It can also be useful in surprising ways. A lot of countries print paper money and other important documents with ink patterns that only show up under ultraviolet light. It’s easy to tell if the money or document is a fake if those hidden patterns don’t glow under a blacklight. Some diseases cause the sick person’s urine to glow specific colors under ultraviolet light, which helps a doctor determine what’s wrong with the person so they can be treated. If you have access to a blacklight, remember that even though you can’t see most of the light it emits, it can still hurt your eyes, so don’t stare into it.

Sometimes a person’s eye is diseased or damaged so they have to have the lens replaced with an artificial lens. Very rarely when that happens, the person wakes up after surgery and discovers they’re seeing ultraviolet way more than the rest of us. They report that the color is a pale purplish shade. This sounds cool, except that they have to wear special glasses that block ultraviolet light when they’re outside, since ultraviolet light can damage the eyes. It’s also the spectrum of light that causes sunburns. That’s what the UV means in products that say they block UV light; UV just means ultraviolet.

Many birds have a special cone cell that reacts specially to ultraviolet wavelengths. Urine reflects ultraviolet light, which allows predatory birds to track their prey by following urine trails. Some rodents and marsupials also have this cone cell. Researchers think having four types of cone cells, the three humans have plus the ultraviolet one, used to be the default in all animals, but some have evolved to not have the ultraviolet cone cell since they don’t need it. Some animals only have two types of cone cells, like mice, who can’t see as many colors as humans.

Researchers are just learning that many mammals are able to see ultraviolet much more than the typical human can. Reindeer, for instance, and some common animals like dogs, cats, and ferrets. Since power lines give off ultraviolet light, sometimes in bursts called coronal discharges, researchers now realize animals are affected by the light even though humans can’t see it. Reindeer have always avoided power lines, and now we know why. To them, the coronal discharges are a blaze of bright color that probably hurts their eyes, especially when it reflects off snow. Conservationists are calling for better shielding on power lines to cut down on the light they give out.

Some humans are born with ultraviolet-sensing cone cells, a condition called tetrachromacy. Since the lens of the human eye naturally filters out most ultraviolet light, people can have this extra cone cell and not even know it. They just tend to be better at differentiating colors than people without it. Some studies suggest that as many as 50% of women and 8% of men may be tetrachromatic—and that tetrachromatic women are also carriers of the trait of red-green color blindness. Since my dad was colorblind, that means I carry that trait from the genetic material I inherited from him, but I see colors really well…so maybe I have those extra cone cells! That’s exciting! Maybe you have it too!

But before we all get too excited, think about the mantis shrimp. Instead of four types of cone cells, it has up to 16 types.

Ultraviolet lightwaves are short. Shorter than that are X-rays, and shorter than those are gamma rays, which are ridiculously teeny. If your eyes could see X-rays, it basically just means you’d see a lot of skeletons walking around and it would feel bright all the time even if you closed your eyes, since X-rays penetrate less dense material like skin. If you could see gamma rays, all it would mean is that you could see stuff that was radioactive. Useful, yes, but not everyday useful.

Infrared is a different case, since infrared wavelengths are extremely long. Some animals can see infrared, but mostly they actually sense heat signatures given off by other animals. Night vision goggles work like this, basically allowing whoever wears them to see in infrared. Wavelengths longer than infrared are microwaves and radio waves, which nothing can see because it would pretty much just overwhelm the vision and you could see nothing but light, much of it the afterglow of the Big Bang, when the universe came into being.

A few years ago, a team of scientists working with an infrared laser started reporting occasionally seeing flashes of light where there shouldn’t be visible light. They were scientists, so of course they investigated with a scientific study of the infrared laser on human vision. This was a powerful laser that only emitted infrared light, and emitted it in quick pulses that released a set number of photons at a time. A photon is one particle of light, something along the lines of an atom. I’m not a physicist and don’t really understand it. The study revealed that sometimes, when the laser’s pulses were extremely close together, two photons would be absorbed by a single photopigment in the eye, which was enough to activate the pigment and allow the person to see a flash of light. But because the eye combined the photons, the eye reacted as though the wavelength of the light was half its length, which made it look green.

By the way, rod cells, the ones that help us see in low light, take a few minutes to achieve full sensitivity. That’s why it takes a few minutes for your eyes to adjust after you turn the light out at night.

It’s mind-blowing to think that light is an actual physical thing that actually physically goes into your eyeballs to let you see. There’s more to it than that, of course—nerves and the brain have a lot to do with how we are able to make sense of visual images. If something goes wrong with the eyeball, the nerves that connect it to the brain, or the part of the brain that deals with vision, it can lead to blindness of one kind or another. But at the very basic level, when you see, for instance, a hedgehog, it’s because light photons bounced off that hedgehog and into your eyeball. And that also means that when you look up at the night sky and see stars, you’re seeing the actual physical lightwaves given off by stars millions of light years away that physically go into your eyeball and bounce off the cone and rod cells, activating them and allowing your brain to form an image. That’s amazing, no matter if you can see ultraviolet or if you get the colors of candy mixed up because they look alike to you.

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.

Episode 306: Two Million Years Ago in Greenland

This week we’re going to learn about a brand new study in Nature about animals and plants that lived in Greenland about two million years ago.

Happy birthday to Dillon!

Further reading:

A 2-million-year-old ecosystem in Greenland uncovered by environmental DNA

Scientists Reconstruct 2-Million-Year-Old Ecosystem from Environmental DNA

No bones? No problem: DNA left in cave soils can reveal ancient human occupants

Greenland now:

Greenland two million years ago [art by Beth Zaiken, taken from the second article linked above]:

Show transcript:

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

This week we’re going to do something a little different and talk about a new study just published in the journal Nature. A little section of this episode is taken from a recent Patreon episode, for those of you who listen and think, “Wait, I’m pretty sure I’ve heard that before.”

Before we get started, though, we have a birthday shoutout! A great big happy birthday to Dillon! I hope you do something really silly and fun on your birthday, like dance around wearing a ridiculous party hat and then eat cake.

Greenland is a big island off the eastern coast of Canada, but way far north, more or less in the Arctic. Even though it’s off the coast of North America, it’s considered part of Europe because for the last thousand years, it’s been controlled by Norway or Denmark at various times. Denmark’s got it right now. A little over 56,000 people live there today, most of them Inuit.

A big part of Greenland is covered in an ice sheet over a mile thick, which is so heavy it has pushed the central section of the island down so that it’s almost a thousand feet, or over 300 meters, below sea level. The land is much higher around the edges of the country. Basically Greenland is a gigantic bowl full of ice.

In 1966, the U.S. Army drilled into the ice to see what was under it, and the answer is dirt, as you might have expected. They took a 15-foot, or 4.5 meter, core sample and stuck it in a freezer, where everyone promptly forgot about it for 51 years. At some point it ended up in Denmark, where someone noticed it in 2017.

In 2019, the frozen core sample was finally studied by scientists. They expected to find mostly sand and rock. Instead, it was full of beautifully fossilized leaves and other plant material.

The main reason scientists were so surprised to find leaves and soil instead of just rock is that ice is really heavy, and it moves—slowly, but a mile-thick sheet of ice cannot be stopped. If you remember episode 277 about the rewilding of Scotland, you may remember that Scotland doesn’t have a lot of fossils from the Pleistocene because it was covered in glaciers that scoured the soil and everything in it down to bedrock, destroying everything in its path. But this hasn’t happened in Greenland.

Where the ice sheet now is, there used to be a forest. Obviously, the ice sheet hasn’t always covered Greenland. Research is ongoing, but a study of the sediment published in 2021 indicates that Greenland was ice free within the last million years, and possibly as recently as a few hundred thousand years.

If you go back a little farther, around two million years ago, Greenland was radically different. Not only was it ice free, it was much warmer than it is today. In north Greenland, which is now a polar desert, there was once an open forest where an incredible number of plants and animals lived. We know because of environmental DNA sequencing, often referred to as eDNA.

At this point most of us have a good understanding of what DNA is, but I’ll give you a quick explanation in case you’re not sure. DNA stands for Deoxyribonucleic acid, and it’s a polymer chain found in every organism’s cells that contains genetic instructions, essentially a guide on how to grow a particular type of animal. It’s way more complicated than that, but that gives you a basic idea. When cells replicate as an organism develops, either from an egg cell or a seed, the DNA directs what sequences of development happen at what stages. You inherit DNA from your parents but your personal DNA is always a little different from both parents’.

True crime podcasts talk about DNA a lot because every individual organism has a unique DNA profile, and since every single cell in our bodies contains DNA, criminals leave their unique signature at every crime scene. Now that scientists can sequence DNA from really tiny samples, many crimes have been solved when the only evidence was something like “this criminal murdered someone and then smoked a cigarette, and left the cigarette butt, and the DNA from their saliva on the cigarette butt was sequenced and run through a database of criminal DNA profiles, and now we know who the murderer is.” And then you get six commercials for mattresses and phone games.

But animal podcasts talk about DNA a lot because every species of organism has a unique genetic profile in addition to having a unique personal genetic profile. Scientists can retrieve DNA from a poop found in the forest and determine what species of animal left that poop. It probably wasn’t a Bigfoot. Scientists can also compare DNA from different animal populations to learn how closely related they are.

The most recent advance in DNA studies is environmental DNA, and it’s increasing our knowledge of the world in amazing ways. If you look at a lake, even if you go Scuba diving in the lake, even if you send a rover down to look at things in the lake, you won’t be able to see every single animal and plant and other organism that lives there. Fish are always moving around and may swim away from a diver or rover, or the water may be murky, and lots of animals stay hidden in the mud at the lake’s bottom. But if you take samples of the lake water and test it for DNA, suddenly you’re going to have more information than what you’d gather in days or weeks of just looking. Of course it’s important to observe animals in their natural habitats, but if you need to know whether an invasive species is living in the lake, or if an animal that hasn’t been seen for a long time is still extant in the lake, or if there are animals in the lake that no one’s ever seen before, eDNA can do that. The water is full of genetic material shed by different organisms.

It’s not just water, either, although testing water samples is pretty easy. DNA degrades quickly in ordinary circumstances, so while you can test soil to see what animals and plants live nearby, in most cases you’ll only find DNA that was deposited recently. But if the soil has been protected from sunlight, weather, and oxygen, such as soil found in a cave, there’s a chance that some ancient DNA can be found in it. That can tell us a lot about what animals lived in the cave a long time ago.

It’s not a few genetic sequences found in a single sample, either. As one scientist put it, there are trillions of DNA fragments in every single spoonful of dirt. Not all the samples are complete enough to sequence, but the ones that are can tell us a lot about the organisms that encountered that spoonful of dirt when it was at the surface of the cave. In Denisova Cave in Siberia, where a few remains of the Denisovan people were first discovered, researchers have learned that Denisovans and Neandertals lived in the cave for tens of thousands of years at different times, even though there aren’t any bones or artifacts remaining.

But the sediment from the Greenland eDNA study wasn’t from a cave. It had been preserved in permafrost for two million years without anything disturbing it, especially humans. It’s the oldest eDNA that’s been studied so far, more than a million years older than the previously oldest DNA. That was also found in permafrost and was recovered from a mammoth tooth.

Two million years ago in northern Greenland, poplar, birch, and thuja trees grew in an open forest along with various shrubs and other plants like ferns and moss. The thuja is sometimes called the tree of life or arborvitae and it’s an evergreen tree that’s related to junipers, sequoias, and cypresses. A lot of the plant DNA found was a surprise, since pollen from the plants had never been recovered in the area. Lots of plants related to modern roses and azaleas grew in the area, so we know there were flowers in spring and summer.

The area is called Kap København, and while it was still pretty cold, it was warm enough that much of the Greenland ice sheet had melted. In winter the temperature might have sometimes been as warm as 50 degrees Fahrenheit, or 10 Celsius, and only dipped to around 2 degrees Fahrenheit on average, or -17 Celsius. This is a whole lot warmer than modern days, where the winter temperature can drop to -50 Celsius, which is about the same in Fahrenheit, and almost never climbs above freezing except in summer.

Some of the animals that lived in the forest two million years ago were mastodons, reindeer, hares, geese, and various rodents related to voles and lemmings. There was even horseshoe crab DNA found from coastal water that had been pushed farther inland during flooding. All the animals found are related to modern animals that still live today, but only one, the Arctic hare, had actually been found in the fossil record in Greenland. They also found DNA of ants and fleas, plankton, algae, and lots of microbial life.

There is no ecosystem on earth today that quite matches that of Kap København from two million years ago. Until this study, scientists thought that not much lived in the area at the time, certainly not mastodons. Hopefully, environmental DNA can be recovered from even older sediments so we can learn more about the ancient world.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 277: Rewilding Scotland

This week is Caitie Sith and Dave’s episode! They want to learn about animals reintroduced to Scotland, especially the Highland wildcat!

The Scottish (or Highland) wildcat:

The Eurasian lynx:

The Eurasian beaver (with babies!):

The white-tailed eagle:

Reindeer in Scotland:

The pine marten:

Show transcript:

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

This week is Caitie Sith and Dave’s episode, where we’ll learn about the re-wilding of Scotland! Re-wilding is the process of restoring an ecosystem to its natural state, basically reversing habitat loss. Most of the time there’s a lot more to it than just reintroducing native animals, but sometimes that’s all that’s required.

Scotland is a part of the island of Great Britain, north of England. People have lived there since the last glaciers melted at the end of the Pleistocene, around 12,000 years ago. During the Pleistocene and a few thousand years after the glaciers melted, Scotland was connected to Europe by a lot of marshy land where today there’s ocean, and naturally many animals lived in Scotland that were also found in Europe at the time. Some of the ice age megafauna that lived in Scotland included the woolly rhinoceros, woolly mammoth, bison, aurochs, wild boar, saiga antelope, giant deer, red deer, reindeer, moose, wild horse, beaver, walrus, Polar bear, brown bear, lynx, wolf, Arctic fox, and cave lion. Many fossil and subfossil remains of Pleistocene animals were destroyed by the formation and movement of thick glacier ice, which scoured the land down to bedrock in many places, so those are only the animals we know for sure lived in Scotland.

But Scotland wasn’t covered by glaciers all the time. The Pleistocene wasn’t a single ice age but a series of cold events interspersed with warming trends. During these interglacial periods, which lasted some 10- to 15,000 years at a time, animals would move to Scotland from other places or become more numerous than before. Then the climate would start cooling again, glaciers would slowly form over many years, and animals would move to areas where there was more food. This happened repeatedly over a period of more than 2.5 million years.

In other words, while we have some fossils of Pleistocene animals that once lived in Scotland, we don’t have nearly as many as have been found in England, Ireland, and Wales. But what we do know is that Scotland was once teeming with all kinds of animals we’d never associate with the country today, like cave lions and Polar bears!

Much of the ice age megafauna went extinct around 12,000 years ago when the last glaciers melted and the climate started warming. Cold-adapted animals couldn’t always survive in a warmer climate, not to mention that as the climate changed, the types of plants available to eat changed too. Some animals migrated away or went extinct, while some were able to stay in Scotland successfully. This included the red deer, reindeer, wild boar, walrus, brown bear, and lynx.

If you’re wondering why that list is full of animals that don’t actually live in Scotland these days, like the brown bear and lynx, it’s because humans hunted many of the native Scottish animals to extinction. Others went extinct due to habitat loss or competition with introduced animals. Many surviving species are endangered today for the same reasons.

For example, the Scottish wildcat, also called the Highland wildcat. We talked about it briefly in episode 52 way back in early 2018. One of the animals that migrated to Scotland after the Pleistocene, but before sea levels rose and cut the British Isles off from Europe, was the European wildcat. The Scottish population has been separated from the European population for at least 7,000 years, and some researchers think it should be classified as a subspecies of European wildcat.

The Scottish wildcat is a little larger than a domestic cat and is always tabby striped. It has a bushy tail with a black tip, a striped face and legs, never any white markings, and is usually dark in color with black paws. It’s a solitary animal that mostly lives in woodlands, where it eats mice, voles, and other rodents, rabbits, and birds. It used to be common throughout much of the British Isles, but these days it’s only found in parts of Scotland.

You’d think people would be excited to have a genuine wildcat living in their country, since wildcats are pretty awesome and eat animals that can damage crops. But for some reason, until recently people thought these wildcats were pests and would shoot them on sight. Some people thought the wildcats were killing game birds, which is rare, or that they were dangerous, which isn’t true. At the same time, the people shooting wildcats were letting their domestic cats roam freely, which has caused an even bigger problem to wildcats than getting shot at.

Like other wildcat species, the Scottish wildcat can and will cross-breed with domestic cats. The resulting kittens are fertile, meaning they can have babies with either wildcats or domestic cats. Kittens are great, of course, but domestic cats are a different species from wildcats. Hybrid cats are less suited to live in the wild, but too wild to be good pets, and if too many domestic cats breed with wildcats, soon there won’t be any real wildcats left. Not only that, domestic cats carry diseases that wildcats can catch.

The Scottish wildcat is a protected species these days, with conservation efforts in place to keep the wildcats and their habitat as safe as possible. One important step is to encourage people to get their domestic cats neutered. This is healthier for pet cats anyway and will help keep tomcats from spraying and fighting, and of course it stops them from having kittens with wildcats.

Another felid that once lived in Scotland is the Eurasian lynx. It still lives in parts of Asia and Europe, but it went extinct in Scotland several hundred years ago, mainly due to deforestation and hunting for its fur. It’s about 28 inches tall at the shoulder, or 70 cm, and is a heavily built animal with thick spotted fur and a short bobtail. The tip of its tail is black although the rest of the animal is mostly tan or brown with darker brown spots, and it has long black tufts of fur on the tips of its ears. It’s slightly bigger than the related Canadian lynx.

Conservationists have wanted to reintroduce the Eurasian lynx to Scotland for years. Since the lynx is threatened in the rest of its range by habitat loss and hunting, reintroducing it to its former range in Scotland would help it and the ecosystem in general. With no large predators to keep their numbers in check, the population of roe deer in Scotland is too high to be healthy, and the lynx loves to eat roe deer.

Some people worry that if the lynx is reintroduced to Scotland, it will be dangerous to humans and livestock. But the lynx is a shy, solitary animal that avoids humans as much as possible. There are enough roe deer alone to sustain a population of over 400 lynxes in the wilder parts of Scotland, especially in the Highlands. The lynx also spends almost all of its time in forests and doesn’t like open pastures. It’s been successfully reintroduced to its former range in other countries, with a nice side effect being increased tourism to national parks where it’s now found.

Scotland also used to have beavers, which were hunted to extinction in the 16th or 17th century. Then, in 2009, the Eurasian beaver was reintroduced to parts of Scotland and is doing great! There are more than 1,000 beavers living in Scotland now. Beavers are considered a keystone species, a term we haven’t really examined on the podcast before, but it means that an animal is so important to an ecosystem that if it goes extinct in an area, the ecosystem sort of falls apart and many other animals go locally extinct soon after.

Beaver ponds create a winter habitat for many types of fish, and beaver dams don’t stop fish like salmon that migrate upriver to spawn. The dams help reduce flooding, improve water quality, and create cover for lots of fish and other animals.

Naturally, though, some people complain about the beavers, because there will always be someone who complains about anything. Some people think beavers eat fish and will eat up all the fish that humans want to catch. Beavers actually don’t eat fish at all, they only eat plant material. Some people think beavers carry the giardia parasite, which causes a bacterial infection sometimes called beaver fever that’s spread in water, but giardia is actually mostly spread by domestic dogs. Some people complain that beavers fell trees and build ponds, and both these things are true. But the beaver is just doing what it’s supposed to do, and as we just learned, this tree felling and pond-making are good for the environment—unlike humans, who chop down lots of trees and make artificial ponds when landscaping, while simultaneously draining wetlands, which doesn’t help the local environment at all. Besides, the beavers are cute and attract tourists who want to get pictures of them, which is also good for the local economy. Everybody wins when there are beavers around, is what I’m trying to say.

The beavers reintroduced in 2009 aren’t the only beavers in Scotland. In 2001, people started seeing them around the river Tay—but no one knew where they came from. Well, presumably someone knew, because the beavers didn’t get there without help. If this reminds you of episode 48, where we talked about some mystery beavers that appeared in Devon, England, the Devon beavers showed up in 2013, twelve years after the Scottish mystery beavers. At first the Scottish government planned to capture the Tayside beavers and keep them in captivity, but the beavers are still there and doing very well.

It’s great that over a thousand beavers live in Scotland now, but that’s actually not very many. Still, it’s a whole lot better than the number of Eurasian beavers about 150 years ago, when researchers think there may have been as few as 300 individuals alive in the whole world.

Another animal that once lived in Scotland, was hunted to extinction, and then mysteriously reappeared recently is the wild boar. They first appeared in the 1990s and by now there are thousands of them in Scotland. It’s possible they escaped from farms, where they’re sometimes raised for meat like domestic pigs. While they’re a native species, they don’t have any predators in Scotland and are causing a lot of damage as they become more numerous. The wild boar’s natural predator is the wolf, and the last wolf in Scotland was killed in 1743. Lynxes will also kill wild boar piglets.

Some birds have been reintroduced to Scotland too. The white-tailed eagle is a type of sea eagle, closely related to the bald eagle of North America although it’s slightly larger than the bald eagle. The biggest ever reliably measured was a specimen from Greenland with a wingspan of 8 feet 4 inches across, or 2.53 meters, just a smidge larger than the largest bald eagle wingspan known. It’s mostly brown and gray with a yellow bill and feet, and a white tail. It lives around water and eats a lot of fish, but it also eats lots of carrion, gulls and other birds, and occasionally small mammals like rabbits. It always lives near water but it prefers wooded areas, especially lowlands and forested islands.

The white-tailed eagle went extinct throughout Britain in the early 20th century when people decided they wanted all those fish the eagle eats for themselves. Never mind that even a thousand eagles couldn’t eat as many fish that a single commercial fishing boat catches in a day. People also decided that eagles killed lambs, even though this is extremely rare. White-tailed eagles would much rather eat fish and seagulls than lamb. The last white-tailed eagles in Scotland were shot and killed in 1916.

As if that wasn’t bad enough, white-tailed eagles were also killed throughout the rest of their range and were especially vulnerable to the chemical called DDT. DDT was a popular pesticide developed in the 1950s and used to kill insects on crops and gardens. But DDT is dangerous, because like other pesticides it doesn’t just do its job and evaporate. It stays in the environment and ends up in the bodies of animals, including people. It’s especially bad for birds that eat a lot of fish, since a lot of pesticides end up in the water, and it causes their eggshells to become so thin and weak that the eggs break when the mother tries to keep them warm. This is the same thing that almost drove the bald eagle to extinction in North America. By the time DDT use was banned in many countries and the white-tailed eagle was declared a protected species, it was almost too late.

Conservation efforts have helped stop the white-tailed eagle from going extinct and its numbers are slowly growing. Starting in 1975, young eagles were brought from Norway to Scotland, where they were successfully reintroduced in the inner Hebrides islands and have now expanded to other parts of Scotland. Some people still complain about the eagles and sometimes shoot or poison them even though it’s illegal, but most people are happy to have them around, especially birdwatchers.

Scotland even has some reindeer these days. Reindeer probably lived in Scotland until around the 12th century, and in 1952 a Swiss herdsman thought they should still be there. He brought a small herd to the Cairngorm mountains, which is now a national park. The reindeer are semi-domesticated but roam free, and they attract tourists who hope to catch a glimpse of them.

At the same time that many native animals have gone extinct, lots of non-native animals have been introduced to Scotland, including wallabies, American mink, gray squirrels, various species of crayfish, and many more. Conservationists are working to minimize the damage these introduced species cause. Many invasive species were animals kept as pets that either escaped or were released into the wild. We talked about the invasive eastern gray squirrel versus the native red squirrel in episode 241, for instance. People released gray squirrels into parks in England because they were so cute, and a hundred years later, the gray squirrels are taking over in many places. They’re increasingly common in Scotland, although Scotland has a small predator called the pine marten that loves to eat squirrels.

The pine marten is a type of mustelid, or weasel relative, that’s common throughout much of Europe and Asia. It grows about two and a half feet long, or 75 cm, including its bushy tail. It mostly lives in wooded areas and spends a lot of its time in trees, hunting squirrels and other small animals like frogs, insects, and birds. It will also eat carrion, bird eggs, and sometimes fruit. It’s mostly brown with a cream-colored throat. It even has partially retractable claws like a cat to help it climb trees, although it’s not related to the cat.

The pine marten is especially good at catching squirrels, and it tends to target the gray squirrel because it’s easier to catch. The red squirrel is more cautious. Where there are pine martens, there are fewer or no gray squirrels. The problem is, the pine marten is considered a pest that kills game birds, so some people shoot or poison it even though it’s a protected species. Then those same people complain about all the gray squirrels around. The pine marten is doing well in many parts of Scotland, though, and has even expanded its range slightly in the last few years.

Scotland is a beautiful country known for its wild and rugged countryside. It wouldn’t take much to rewild it properly, a process that’s well underway with keystone species like beavers already re-established in many places. The main problem is people who don’t understand that a healthy ecosystem requires predators. Without lynxes, wolves, bears, and other large predators, animals like roe deer and wild boar become so numerous that they can’t find enough to eat and either starve or destroy crops and gardens.

Fortunately, many more people in Scotland do understand the importance of building healthy ecosystems. After all, they’re naturally proud of where they live and want to make it even better.

You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at strangeanimalspodcast@gmail.com. If you like the podcast and want to help us out, leave us a rating and review on Apple Podcasts or Podchaser, or just tell a friend. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes.

Thanks for listening!

Episode 030: Reindeer and Moose don’t confuse them

In Episode 30, I admit a M I S T A K E, in that I did not realize Finland has a sizable moose population and so therefore assumed that although this thing looks like a moose, it must be a reindeer head. So because I made a M I S T A K E, the whole class is being punished by learning about reindeer and moose of Finland.

Oh yeah, I’m back from my trip to Finland. I had a great time!

Finnish forest reindeer:

Barren-ground caribou:

Finnish moose:

Alaskan moose:


Oh, here’s a link to information about my new book! More details coming next week.

Show transcript:

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

This is the first episode I’ve put together since returning from Finland last week. I had a great time on my trip! WorldCon was amazing, I got to hang out with some good friends, and I had lots of positive feedback after the panel I was on. One day I went to a fun Viking-themed restaurant with my friends Emma and Dave (hi guys!), where I ordered reindeer. It was really good, and when I got my food I tweeted a picture of the plate along with a picture of a stuffed animal head across from me. I captioned it something like, “A reindeer is watching me eat reindeer.”

Unfortunately, that wasn’t a reindeer head. It was a moose head. When I first saw it I knew it was a moose head, but I didn’t believe myself that it was a moose head because there’s no moose in Finland, right? Just reindeer.

Five thousand replies correcting me later, I sheepishly admitted that I was wrong and swore I would in the future trust myself to ID moose heads versus reindeer heads without convincing myself I was wrong. And just to clear things up, here’s an entire episode on certain hoofed Ice Age megafauna that live in Finland.

The reindeer living today are all one species, Rangifer tarandus, although there are a number of subspecies. Reindeer evolved about 3 million years ago and are closely related to moose.

During the late Pleistocene, better known as the ice ages, reindeer were much more widely spread than they are today. You could have found herds of reindeer in Tennessee and Spain during the last glaciation around 12,000 years ago. These days, wild reindeer are found in Norway, Finland, Iceland, and Siberia, and in Alaska, Canada, and Greenland. In North America, reindeer are called caribou. Wild reindeer and caribou numbers are in decline worldwide due to climate change and habitat loss.

Most reindeer are migratory to at least some extent. Some populations of caribou in North America migrate 3,000 miles a year. The only mammals that migrate farther than that are whales. Mating occurs during autumn migration, and calves are born after spring migration in May or June.

Reindeer have larger hearts than other ruminants of about their same size, which helps them run and swim for extended periods of time in cold environments. Reindeer knees click when they walk, and researchers believe this helps individuals keep track of each other in white-out conditions.

Reindeer eat leaves, twigs, some types of grass, and mushrooms, but their primary food in winter is the reindeer lichen. Mammals don’t typically eat lichens, but reindeer have developed a special enzyme called lichenase that helps them digest it. In spring they may also eat bird eggs, fish, and rodents when they can catch them. Instead of secreting urea in their urine as almost all mammals do, reindeer retain it within the digestive system for the nitrogen it contains.

Now, in my defense, the reindeer I’m familiar with are North American caribou, and many caribou have somewhat palmate antlers and heavy muzzles that kind of resemble moose. At least at first glance, especially if you’re convinced you’re looking at a reindeer head and not a moose head. Most reindeer in Europe have slenderer muzzles and more typically deer-like antlers. Reindeer have the largest antlers to body size of all living deer species, even counting the moose. Moose antlers are larger, but moose bodies are also bigger. Some mature male forest reindeer can have antlers almost seven feet wide with up to 44 points. Both females and males grow antlers, although females have smaller antlers and individuals in some populations don’t grow them at all. While males shed their antlers soon after the rut season, females keep theirs all winter and use them to defend their feeding areas from other reindeer.

In winter reindeer hooves are sharp and hard like ordinary deer hooves, which helps them keep a good purchase on ice and allows them to dig through snow to the lichen beneath. In summer, though, when the ground is muddy and soft, the hooves become more like spongey footpads to help spread their weight across a larger surface.

The first mention of reindeer herding comes from the ninth century, but the Sámi people, once called Lapps, of what is now northern Finland, Sweden, and Norway had probably domesticated reindeer long before that—at least 2,000 years ago and possibly as long as 7,000 years ago. The Sámi were traditionally nomadic, moving with their herds. They used reindeer for meat, milk, fur, and transport. These days reindeer herding is pretty hands-off, with herds moving around as they like while the herders check them periodically using ATVs or snowmobiles. But reindeer herding is an important aspect of Sámi culture, and extensive knowledge of reindeer and weather is still passed down mostly orally.

While reindeer have been at least semi-domesticated for thousands of years, the caribou of North America have never been domesticated, although many native cultures in North America depend on caribou hunting. As a result, domesticated reindeer tend to be heavier than caribou, migrate much shorter distances, and calve earlier in the year.

Next, let’s talk about moose. In North America, moose are called moose. But in Europe, moose are called elk.

The word elk is old and comes from the same Germanic root language that Old English evolved from. The word moose was borrowed from the Algonkian languages at the end of the 16th century. So I guess it’s inaccurate to say that it’s wrong to call your moose elk. I mean, before the 16th century people in Europe had to call moose something and the word elk was just sitting there. What we call elk in North America is a totally different large deer, native to North America and parts of Asia. But since the word moose is just fun to say, I don’t know why people in Europe haven’t adopted it. Then again, I also don’t know why we call elk elk and not WAH-pah-tee [wapiti] in North America, since wapiti is another Algonkian word.

But yes, moose do live in Europe, specifically northern Europe and parts of Russia. Moose did once have a much larger range. Moose remains only 3900 years old have been found in Scotland, but once the moose died out, the word elk was just floating around with nothing to fasten itself to, so for a long time people in Britain used the word elk to refer to any large deer, especially red deer—which resemble North American elk aka wapiti.

Anyway, I’m calling them moose and we’re not going to discuss the wapiti in this episode because I’m already confused enough as it is.

Like the reindeer, there is only one species of moose but several subspecies. The biggest are the Alaskan moose and the East Siberian moose. Big males of both can stand over seven feet tall at the shoulder and weigh over 1500 pounds. The moose subspecies of North America generally have larger antlers with two lobes each, whereas Eurasian moose subspecies typically have one lobe each. The largest spread of antlers ever measured was just under seven feet across. Only male moose grow antlers.

The moose likes marshy or wet areas and eats a lot of aquatic plants, although it will also rear up on its hind legs to reach tree leaves. It eats leaves, twigs, and roots, and prefers low-fiber plants. It can’t digest hay. Moose have even been known to dive to reach plants. Its nostrils seal when underwater, which allows it to eat without lifting its head out of the water.

Moose evolved around 2 million years ago in Europe, with the earliest known species called the French moose. It was actually bigger than the Alaskan moose but looked more like a deer. It didn’t have the modern moose’s heavy snout and its antlers were over eight feet across, mostly just one unbranched beam with a small palmation at the ends. By around a million years ago the French moose had given rise to the broad-fronted stag moose, which migrated from Eurasia to North America. It looked more like its modern descendant.

Like all deer, moose and reindeer have no upper incisors, just a hard palate. Both are also ruminants, which means their food goes through a complex system of bacterial fermentation, including needing to be regurgitated and rechewed as cud, so that the animal can extract as much nutrition from low-protein plant food as possible.

Around 100,000 moose live in Finland and hunting permits are limited each year to roughly the same number as calves born that year. Moose sound exactly like you’d expect them to sound, like this:


While I was in Finland, I didn’t find as much time to bird as I’d planned. But my first night in Helsinki let me see an animal that I didn’t expect to see at all—I didn’t, in fact, know it was an animal that ever lives in cities. I won’t go into the reason why I was wandering around Helsinki at 3am on a Monday because it’s a long story without much of a payoff. But while I was out and about, I kept seeing an animal that at first I couldn’t identify. At first glance I thought it was a huge rat, but its legs were too long. Then I thought it might be a dog, but it wasn’t shaped right. It took me several sightings to realize I was looking at a hare, probably the European hare.

I’d never seen a hare before. I’m used to our cottontail rabbits, which are adorable and have tails like powder puffs, but which aren’t very big. This hare was easily over a foot tall with long legs, and it was hopping busily around the quiet streets of Finland’s largest city under the light of a full moon.

That’s it for this episode—apologies for how short it is, but I am unbelievably jetlagged. If you’re listening to this one the week it comes out, I’ll be at DragonCon this weekend. If you’re going to be there too and want to say hi, feel free to email or tweet at me! After DragonCon my schedule should go back to normal.

Oh, and one last thing—I have a book out! I’ll talk about it more in next week’s episode, but if you’re interested, the book is called Skytown and it’s a fun steampunk fantasy adventure about a couple of ladies who are airship pirates. It’s available in paperback right now but should soon be released as an ebook too. It’s published by Fox Spirit Books. I’ll put a link in the show notes.

Anyway, 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. If you like the podcast and want to help us out, leave us a rating and review on iTunes or whatever platform you listen on. We also have a Patreon if you’d like to support us that way. Rewards include stickers and twice-monthly bonus episodes.

Thanks for listening!