The Science of Birds - Finches

Episode Date: February 5, 2021

All about the ‘true’ finches, the species belonging to the family Fringillidae. These small songbirds are found in many places around the world. Most of them specialize in eating seeds. Not every bird we commonly call ‘finch’ is a member of this family. And the family includes many birds that don’t have the word ‘finch’ in their common name. Confusing? Yes. We’ll try to clear some of this up for you.Learn about the key features of finches as well as their global distribution, evolution, feeding, and more.There’s lots of fun stuff to know about these charming birds!~~ Leave me a review using Podchaser ~~Link to this episode on the Science of Birds websiteSupport the show

What comes to your mind when you hear the word Finch? Maybe you think about Finch County in New South Wales, Australia. Or perhaps you remember Finch, the Dutch progressive hard rock band from the 1970s. Or what about Atticus Finch, the fictional lawyer from the novel to kill a mockingbird? And hey, speaking of birds, just maybe the word Finch conjures up images of small energetic songbirds that flit around in your garden. I hope the latter is the case because we're about to embark on

an exploration of birds we call finches. Some of them, anyway. If you were hoping to listen to a podcast episode about progressive rock music from the Netherlands, you're in the wrong place, sorry. As for birds, I'm guessing you know a little something about gold finches, house finches,

zebra finches, chaff finches, or Darwin's finches. I must warn you, however, that this word, finch, like the word sparrow, has been thrown around rather haphazardly in the naming of birds. Today we're focusing on one bird family, fringility. The birds in this group are what ornithologists call the true finches. Or as our German friends call them, I can't clickin-finken, meaning the proper or actual finches. or as I like to think of them, the legit finches.

This family of legit or true finches does include those gold finches, chaff finches, and house finches. But there are many other birds we call finches that are not members of this family. Furthermore, the family fringility includes a bunch of birds that don't have the word finch in their name. These include ciskins, euphonias, canaries, red poles, crossbills, and more. Let's see if we can shed a little light on who is and who isn't a true finch. More importantly, let's explore the characteristics of true finches and why these birds are so very excellent.

Hello and welcome. This is the science of birds. I am your host, Ivan Philipson. The Science of Birds podcast is a lighthearted, guided exploration of bird biology for lifelong learners. As I said, this episode is all about the birds in the family fringility. This is the first Science of Birds episode that focuses on a bird family from among the songbirds. And it certainly won't be the last because songbirds make up about 50. 50% of all bird species, and they represent many biological families.

This is a big episode, so let's get the party started. What are the tell-tale features of the true finches? All the birds in the family fringility. For casual observers, like most of us bird lovers, and naturalists, this isn't an easy question to answer. We normally use a bird's size and shape as the starting point for identification. The bird families I've covered in previous episodes have been easier to define by size and shape. Hummingbirds, pelicans, woodpeckers, and kingfishers all have distinct silhouettes.

But with most finches, it can be a challenge to distinguish them from other small songbirds by silhouette alone. The sizes and shapes of finches are often very similar to those of songbirds in other families, like sparrows, for example. This is one reason that a bunch of distantly related birds have the word finch in their common names. These so-called finches are actually members of either the New World Sparrow family, the Wax Bill family, the Indigo Bird family, or the Tanager family. I've griped about common names before on the podcast. There are so many examples where two or more bird species have common names that imply a close relationship, even though they actually belong to different families. This can be confusing, especially when you're

new to the world of birding and ornithology. One example is the world-famous Darwin's Finches on the Galapagos Islands. There's a Pulitzer Prize-winning book about them, titled The Beak of the Finch. It's good. You should read it. But are Darwin's Finches true finches in the family fringility? Nope. They're actually in the family Thraupidae, which is filled with the many colorful tanagers of Latin America. So maybe that book should have been called the Beaks of some finch-like tanagers of the family Thraupidae that live on the Galapagos Islands. With a catchy title like that I'm sure the book would have been just as successful. But we can't really blame people for naming birds this way.

They were just looking at the overall superficial appearances of the birds. Back in the day, no one had genetic data to sort out which birds are related to which. The way it used to work, someone came across an unfamiliar bird in, say, Australia, and they were like, look at that little bird. I've never seen one quite like it. Must be a new species. Jolly good. What should we call it? Well, it looks a bit like one of those finches I recall from my grandmother's garden back in England. I suppose this new bird is a finch then. It's got a dab of purple on its face, so I shall call it the plum-headed finch. That's a real species, by the way, the plum-headed finch of northeastern Australia. It belongs to

the Waxbill family, Estrildidee. In other words, not fringility. The well-known zebra finch is also an Australian bird in the Waxbill family. So the zebra finch is not a quote-unquote true finch. This is all a long way of saying that common names can be misleading. They don't always reflect the real genetic evolutionary relationships among birds. This is certainly, true for the many birds we commonly call finches. So it sometimes takes a little extra effort on our part to figure out which family a bird really belongs to. These days, any respectable bird field guide or mobile app will present species in taxonomic order. Species will be grouped into their respective genera. Genera are grouped

into families and families are grouped into orders. So that's pretty helpful. I recommend spend a little time with your book or app to see which fringillid finch species you have in your neck of the woods. Okay, we've acknowledged that it's not super easy to instantly recognize a true finch from a mile away, the way you can with, say, a heron or a penguin or a roadrunner. But that's okay. And this is going to be the case for many types of songbirds. I mean, where would be the fun if every bird was easy to identify, right? Let's move along and talk about the features of true finches. As for size and shape, these are small to medium-sized birds. Among the smallest finches are the lesser gold finch, the Andean Siskin, and the various euphonia species. These finches

are only about four inches long, so each of these birds is a four-inch finch. Rhymes are fun. what else we got uh flinch cinch grinch meh anyway four inches is about ten centimeters the largest member of the family might be the collared gross beak which lives in the himalayas this beast of a finch is about nine inches long or 23 centimeters finches have compact bodies with relatively largeish heads supported by short necks many of them have tails with notched or forked tips. Plumage colors vary a lot among finch species. Some are rather drab with streaky brown or gray feathers. These guys fall into the category that birders call little brown birds, LBBs. But most finches sport some color, vibrant colors in some

cases. The most common hues are yellow, red, and orange. A smaller number of species have blue or green patches of feathers. The latter group includes most of the euphonias and the chlorophonias of Latin America. The bills of most finches are fairly short, downright stubby in some species. Yes, I'm talking about you, Eurasian bullfinch. Finch bills are cone-shaped, deep, and pointy at the tip. Sure, there are some exceptions, but that's the typical shape. These conical bills are superbly well-suited for cracking open the shells of seeds, and finches

are all about seeds. Seed eating creatures like these are called granivores. The diets of finches are more vegetarian than most other songbirds. They eat almost exclusively seeds and berries all year long. Finches generally have voices that we humans find pleasant to listen to. In other words, they sing pretty. The male songs tend to include chirps, rapid trills, and musical liquid notes. Let's listen to the songs of a few familiar finches.

Maybe you'll agree with me that these songs are kind of similar in terms of their tones and overall vibe. Here's the song of the most commonly observed species in North America, the house finch, Hemoris Mexicanis. House finches are streaky brown birds. The male has a wash of red on his head, throat, and breast. Another common species in North America is the American goldfinch, Spinus Tristus. These are really small birds at about 4.5 inches or 12 centimeters long. Males of this species are lemon yellow with a jet black cap and wings. They sing like this.

Zipping across the Atlantic, we can check out some of Europe's finches. How about the European goldfinch? Cardwellis, Cardwellis. The bird's so nice, they named it twice. Here's a European goldfinch singing. The European goldfinch has a similar shape to the American goldfinch, but it's a somewhat smaller bird. Note that these two species are not in the same genus, which means they're not super closely related, even though that's what their common names suggest.

This goldfinch has some pretty jazzy plumage. It has a bold pattern of red, white, and black on its head, a tan body, and black wings with yellow and white highlights. I think it's really striking, a really cool-looking bird. The Citril Finch, Cardwellis Citronella, is in the same genus as the European goldfinch. Its colors are more subtle, being mostly grayish with soft yellow accents. Here is the lovely song of the Citral Finch singing in the foothills of the German Alps.

How about one more European bird, the common chaffinch, fringilla syllabs? I love that genus name, fringilla, probably because it reminds me of Godzilla, and Godzilla is cool. Anyway, the common chaffinch is, true to its name, a very common species. Europeans, as usual, don't bother calling it a common chaffinch. It's just chaffinch to them. This handsome bird has a blue-gray sort of hood or mantle with a soft pinkish-orange face and body. To get a taste of something a little further afield,

Let's go all the way over to the far east of Russia. Siberia is the home of the long-tailed rosefinch, Carpodacus Sybaricus. This medium-sized finch has, surprise, surprise, a long tail. And its bill is rounded and stubby, sort of like the Eurasian bullfinch. The long-tailed rosefinch is grayish-brown overall, but it has some striking crimson-colored markings on its head and neck. It's got patches of pale pink on its body as well. Here's a male, long-tailed rosefinch singing in a birch woodland in Siberia. And let's do one more, since we're having so much fun.

How about a more exotic species from the tropics? The chestnut-breasted chlorophonia, which has the scientific name chlorophonia pherous, is found in the cloud forests of South America. It's a small, short-tailed bird, and it's about as colorful as you can get for a species in the family fringility. Males and females are both bright blue and green overall, but the male has a little more possess. He's got yellow on his sides and a reddish belly. This is a gorgeous bird. Here is a male chestnut-breasted chlorophonia in Ecuador. We're going to shift gears now and take a look at the diversity

and distribution of the true finches. We're focusing today on a biological family, right? Fringility. But if we climb up one rank or level in our classification system, we have the Order Paceraphormes. The family fringility is one of about 140 families nested within the order Paceraphormes. There are over 6,000 bird species contained in this order.

As a group, we call them songbirds. At least half of all bird species on the planet are songbirds. So finches are songbirds in the family fringility, and that family is in the order Pasariformis, just so we're all on the same page. The name of the family fringility comes from that cool genus name. Fringilla rhymes with Godzilla. Tracing the etymology of the word fringilla way, way back to the early Indo-European language, it meant to make a small noise or Twitter. This evolved to mean small bird in classical Latin. And then it came to be the word for finch in later versions of Latin. Today, we have the honor of sharing the planet with about 210 species of finches. So this is a pretty species-rich

family. Over half of these species belong to only four genera. For example, the genus with the most finch species is Krithagra. The 37 species in the genus Krithagra are African birds, the seed eaters, canaries, serens, and citrils. If we look for the region with the

highest level of finch species diversity, the continent of Asia wins the trophy with 74 species. Of course, we also find some of those same species in Europe. Within the family fringility, there are three distinct

sub-families. A sub-family is a level of classification sandwiched between family and genus. These sub-families are evolutionary lineages or branches that might someday evolve apart or diverge so much that they each become a full-blown family. So briefly, the three sub-families are cardwellany, euphoniani, and fringilony, not fringilidae, but but fringilinni. The Cardwellinae subfamily contains the vast majority of finch species, over 150, so this includes most of the familiar species. The subfamily euphoniani contains those colorful euphonias and chlorophonias from Mexico,

Central America, and South America. This group of 32 species was once placed in the Tanager family, Thraupidae. Unlike nearly all other finches, euphonias and chlorophonias have glossy feathers. Overall, these little dudes just don't fit the image of your standard finch. But the genetic data doesn't lie, and that is what helped ornithologists figure out that these birds are actually finches. The last subfamily is fringilony, which contains only four Eurasian birds, which are the three different chaffinch species plus the brambling. A group of finches that deserve special mention are the Hawaiian honey creepers.

In fact, I plan to do an entire episode on these birds and the other avian fauna of Hawaii at some point. The honey creepers of Hawaii are an amazing group of 18 species in the Cardwellini subfamily. Many of them look nothing like your typical finch. Some have long, downward curving beaks and bright red or yellow plumage. These birds are so unfinch-like that they used to be placed in their own family. Later, they were reclassified and moved to a unique subfamily within the fringility. Now, thanks to recent genetic analyses, we know they actually belong to the Cardwellini subfamily. The many weird and wonderful Hawaiian honeycreepers all evolved from a single lineage of rosefinch from Asia.

These birds represent one of the most spectacular examples in biology of an adaptive radiation. Darwin's finches are another classic example. Excuse me, I mean Darwin's finch-like tanagers, but we can't talk about them because they aren't legit finches. Recall that an adaptive radiation is where one lineage diversifies through evolution into multiple species to fill a bunch of ecological niches. Hawaiian honey creepers colonized, then spread across their remote island chain. They evolved into over 50 species over millions of years.

Some came to specialize in feeding on flower nectar, some were insectivores, some were seed-eating granivores, and so on. Sadly, humans have caused the extinction of many of these honey creepers. Only 18 species are left today, and most of them are inceasing. serious trouble. We'll look at their full story when I make that episode on the birds of Hawaii. As a family, fringilids, our 210 species of true finches, are spread across most of the planet. Some are in the tropics, others live well above the Arctic Circle, or way down to the tip of South America. You'll find finches on all the continents except Australia

and and if you had to take a wild guess what other continent would you assume is devoid of any finchy goodness? That's right, good old Antarctica. Finches are also absent from the South Pacific, including New Zealand. Who knows why they aren't naturally found

in Australia or New Zealand? Notice I used the qualifier naturally there. We humans have done our usual trick of shuffling species around, dropping them off in places where they don't belong. For example, even though there are no naturally occurring native finches in New Zealand, today you can find five species there. These include the common chaffinch, the European goldfinch, and the European green finch.

In North America, our most common species, the house finch, is found across most of the continent. But originally it was a bird seen only west of the Mississippi River. In the early decades of the 20th century, some marketing genius decided to sell house finches as cage birds in New York City, calling them Hollywood Finches. Step right up, folks, we got your Hollywood Finches right here. One dollar gets you two birds, five dollars gets you a baker's dozen. Just feed them seeds and they'll sing you the sweetest song you ever heard.

Hollywood finches come all the way from sunny California, but at these prices they're going fast. So don't be a sucker. Step right up and buy yourself a box of genuine Hollywood finches. This sort of nonsense went on even after 1918 when the Migratory Bird Treaty Act made the sale of house finches and other wild birds illegal. There was actually a secret trading ring

that shipped about 100,000 house finches from California to New York. Eventually, the law started to crack down on these bird-pedaling sheisters. Pet shops and bird traffickers started to set their house finches free out of fear of being busted. Starting in the 1940s, some of these recently liberated birds began to breed in New York. Over just a few decades, they spread across most of eastern North America. Oh, and people released some house finches in Hawaii, too, so the Aloha state is also crawling with introduced house finches.

If we return to look at just the natural distribution of the family fringility, we find there are many habitats used by these birds around the world. Most finches are birds of woodlands, forests, and scrub habitats. But some live in more open environments like savannas, alpine slopes, and deserts. There's even a species called the Desert Finch. rhodospyza obsaleta. This sand-colored bird lives in arid parts of the Middle East and Central Asia. What do we know about the evolution of finches?

Well, we don't have too many well-preserved fossils of these birds. Apparently, one challenge with fossils is that, over the course of the last 65 million years or so, multiple independent bird lineages have evolved a finch-like beak and skeletal structure. So if you have just a fossil, you might not be able to say for sure that it belongs to a species in the family fringility. Genetic data to the rescue! Genetic data calibrated with a molecular clock gives us a rough estimate of when finches probably burst onto the global scene. It looks like the origin of the family fringility was somewhere in Eurasia 10 to 20 million years ago. Fringility is one of the most recently evolved bird families in the world.

That's why you find these birds way at the back of your field guide. This is true at least for field guides to birds of North America, Europe, or Asia. As I mentioned earlier, modern field guides are typically ordered taxonomically. The more ancient slash primitive bird groups are in the front. More recently evolved groups are toward the back. Ducks and geese, for example, are in the first pages because those birds belong to what we know is a super old branch of the avian tree of life. When I'm learning about a family of birds,

one of the things I really want to know is what birds are the closest relatives of this family. The best answers usually come from genetic research published in the last 10 to 15 years. As I've already been pointing out, data from bird DNA reveals the relationships among different types of birds that we might not be able to detect if we looked at only their anatomy or behavior. So who are the closest relatives of our finches? This one is a little tricky to answer. Finches and their close relatives have evolved.

so recently that the lineages of these birds are a little difficult for ornithologists to disentangle. But what we can say is that 10 to 20 million years ago, the family fringility split off from another lineage that includes several families of familiar songbirds, mostly from North America. These include the Cardinal family, New World Blackbird family, New World Warbler family, and Tanager family. So these are all pretty close relatives of Finches. There's one more thing I want to tell you regarding the evolution of finches. In researching this episode, I came across an interesting scientific paper

that offers us a little more insight into this group of birds. The research was conducted by a group at the National Museum of Natural History in Brinot, France. It was published in 2017 in the journal Ecology and Evolution. The researchers analyzed 53 behavioral and anatomical traits across 81 species in the family fringility. These traits included things like migration behavior, diet specialization, typical numbers of offspring, and so on. The researchers wanted to test some ideas about how such traits evolve differently, in stable environments like tropical forests versus in highly seasonal, unpredictable places like the far northern latitudes. They concluded that finches have evolved several ways of life,

several strategies that correspond with different environments. Some sweets of finch traits work well in strongly seasonal, harsh environments like the far north. Other traits are beneficial in relatively easy-going, benign places like the equatorial jungles. In the barbarian strategy, and seriously that's what it's called the barbarian strategy, how awesome is that, in this strategy, the finches are gregarious. They travel in flocks roaming far and wide, you know, like barbarians, like Goths, vandals, Huns, Conan, and similarly scruffy characters. These barbarian finches also raise relatively large numbers of babies each year, and their males and females look more or less the same,

so there's not much sexual dimorphism. Based on this research, it looks like the earliest finches from millions of years ago were probably of the barbarian sort. That's the ancestral strategy. But plenty of finches still live like this today. They refuse to practice proper personal hygiene or adopt other norms of modern polite society. The barbarian way of life works well in challenging environments like the boreal forests of North America and Eurasia. The common red pole, European goldfinch, and pine ciskin are examples of species that fit into this category.

These guys travel around in nomadic flocks. They often produce two or more broods a year and therefore, crank out lots of babies, and their sexes look very similar. The alternative, taken by many finches, is the so-called civilized strategy. These birds have evolved in places where life is far more predictable, places like the tropical lowlands of South America, where the climate is stable and food is relatively plentiful. Civilized birds don't need to. to roam around so much to look for seasonally or sporadically available food. Instead, they

tend to set up and maintain territories. They can lounge around a bit. They're also less gregarious. And because they can devote more time and energy to each of their babies, they don't need to crank out so many of them. In other words, they sort of spoil their kids. Barbarians, on the other hand, raise more chicks and broods every year because life for them is hard and fewer are likely to survive. Barbarian chicks have to face the cold, hard reality of life at a young age. Several of the euphonia species of South America fit nicely into the civilized category. These dapper little birds set up territories and don't move around so much. They're not super gregarious. And they raise only a few offspring each year. Compared to their frenetic barbarian cousins, euphonias live a slower-paced life. They're

more chill. I've only given you a simplified summary of this research, because there are more details and nuances that we don't have time to get into. I'll put a link to this paper in the show notes on the Science of Birds website, so you can check it out if you want to learn more. But you've got to love it, right? Barbarian finches... and civilized finches. Good stuff. All right, you thought we were about done here, but oh no, we still have to talk about Finch conservation,

about how they eat, their migrations, and their breeding. What have you gotten yourself into? I'm going to refill my trusty coffee mug here. And I just want to take a moment to thank everyone who has taken the time to write a review for the Science of Birds podcast. Each five-star review is so helpful and valuable. Here are a couple of my favorites so far. Carl writes, I am by no means an ornithologist or even a casual birder,

but the content and presentation of this show have me totally hooked, real pumped for more and very thankful to the creator for, for sharing his passion with me, even if he has no idea I exist. Well, Carl, you've made your existence known to me, and I thank you, sir. And Eric writes, I just started listening to The Science of Birds, but I'm already a top fan, informative, entertaining, and no unneeded fluff. It's jumped to the top of my podcast list.

Thank you so much, Eric. That's right, there's no unneeded fluff here. I make sure to only include the fluff that you really need. Okay, shall we carry on with our deep dive into the Finch family? So we've got 210 finch species in the family fringility, and this family includes three well-defined sub-families. Let's take a few moments to consider the conservation status of finches around the world. Looking at the IUCN Red List, which is the best resource for this kind of information,

we see that 42 species in this family are classified as being in some sort of trouble. 12 are critically endangered, 11 are endangered, 13 are vulnerable, and 6 are near threatened. Most of the seriously imperiled finches on the planet are concentrated in one small geographic area. Maybe you can guess where. That's right, Hawaii. Of the 12 critically endangered species, 11 are in the Hawaiian islands. And what's really sad is that 17 of the 18 finch species

that have gone extinct in the last few hundred years were also native to Hawaii. These birds were wiped out by humans, of course. Factors include the destruction of Hawaii's forests, the introduction of pigs, rats, and other invasive mammals, and the accidental introduction of mosquitoes carrying avian malaria. Again, this story deserves a whole podcast episode. In Europe and elsewhere, many finch species have been captured in the wild

to be kept as pets in cages. This has been going on for thousands of years since Roman times and before. Cagebirds were all the rage in Victorian Britain. That led to hundreds of thousands of wild finches being captured in the 1800s. The trade in cage birds has often been devastating to finch populations. For example, the red ciskin, spinus cuculatus, is an endangered species in northern South America. males of the species are beautifully colored in red and black. Decades of heavy exploitation for the pet trade

has pushed the red ciscan close to extinction in the wild. Sometimes, finches have been targeted directly for persecution. For example, the Eurasian bullfinch was, until not that long ago, killed by the thousands in England and elsewhere. Why, you ask, who would do such a thing? Well, I guess people who own fruit tree orchards. You see, bullfinches love to eat the buds of fruit trees. Some of those trees are grown commercially, like pears and cherries.

For hundreds of years, parishes all over England actually paid a bounty for every bullfinch killed. So back in the day, you could be a bounty hunter, a bounty hunter of finches. That's way less cool than being a normal bounty hunter. But here's the thing. all of this carnage was probably unnecessary. Some research shows that those fruit trees can lose up to half of their flower buds and still produce just as much fruit when harvest time comes around.

So all those poor little bullfinches may have died for no reason. I mean, I think it's horrific to kill them in any case. And apparently, it's still possible to get a license from the British government to kill bullfinges. I don't own an orchard, but even if I did, I'd say, Leave those finches alone. Now it's time to talk more about what and how finches eat. As I mentioned earlier, the diets of finches are more plant-based than those of most songbirds. All year long, finches are out there eating seeds, berries, flower buds, leaves, and so on.

The reason this is noteworthy is that most other songbirds that eat seeds and berries in the non-breeding season switch to eating more insects and other invertebrates when it's time to raise a family. For example, this is the method of operation for many New World sparrows, like the dark-eyed junco and white-crowned sparrow. Such birds also feed mostly invertebrates to their chicks. This makes sense, right, because invertebrates are rich in protein. Producing eggs requires a lot of protein, and a growing chick needs a lot of protein. But birds like our beloved little American goldfinch just keep on chowing down on seeds in the breeding season. They're granivores through and through. American goldfinches are especially fond of thistle seeds. They even feed

seeds and only seeds to their babies. Finches like this have evolved the ability to get all the protein they need from seeds alone. In episode 12 of the podcast, we looked into the weird world of brood parasites. These are birds that drop their eggs off into the nests of other species. Brood parasites trick other birds into raising their babies. In North America, our best-known brood parasite is the brown-headed cowbird. Well, when a cowbird drops an egg into the nest of an American goldfinch, it has made a big mistake. The cowbird egg hatches and the unsuspecting goldfinches start to take care of the hatchling cowbird as if it was their own offspring. So far so good for the cowbird, right? The baby cowbird begs for food and the goldfinches oblige by stuffing it full

of thistle seeds, but within a few days the cowbird chick dies. It just can't survive on a diet of nothing but seeds. Hashtag cowbird fail. Like the American goldfinch, housefinches, European goldfinches, and a whole bunch of other species are similarly granivorous. This is especially true for the many members of the Cardwellini subfamily. The European goldfinch is is another connoisseur of thistle seeds. Recall that both the genus and species name for this bird is carduelis. This name actually comes from the Latin word for wild thistle. So the bird was named after its favorite food. It's like if my scientific name was Burrito Burrito. Not all finches are so laser-focused on seeds and berries. The common chaffinch has the most very

diet of any bird in this family. It eats mostly small insects and only supplements its diet with seeds. Interestingly, chaffinches are also the most ancestral or primitive of all the living finch species. They're on a little branch of their own at the base of the finch family tree. Remember that the three chaffinch species plus the brambling make up the fringillany subfamily. Remember that? Of course you do. As a quick aside, one of my favorite finch experiences was when I found and photographed a blue chaffinch on Tenerife, which is one of the Canary Islands. These islands are part of Spain, but located off the northwest coast of Africa. I was on my own exploring the islands, and I really wanted to find that bird.

It's endemic to Tenerife, meaning it's found nowhere else in the world. Finally, I spotted a blue chaffinch singing in some pine trees. I spent some quality time appreciating it and snapping a bunch of photos. I was in heaven. The photos didn't turn out so great, but I really treasure the memory. Anyway, back to how finches eat. The diets of birds in the euphoniani subfamily differ from the diets of the more typical finches. Euphonias and chlorophonias are fruit eaters.

They're frugivores, more so than granivores. Most of them are crazy about mistletoe berries, and some eat figs and cultivated fruit like bananas and oranges. They even regurgitate fruit to feed their chicks in the nest. This portion of our program is brought to you by Yum Yum Fruit Salad. Don't have time or the ability to find your own lunch? Try yum yum fruit salad. It's half digested and 100% delicious.

Okay, let's talk about the beak of the finch. No, not that Pulitzer Prize winning book, but the actual anatomical structure of the finch's bill. The classic cone-shaped bill of a finch is specially adapted for cracking open the shells of seeds. Here's how it works. A finch grabs a seed and gives it the old finch pinch, holding the seed between the upper and lower parts of its bill.

We call these the upper mandible and the lower mandible. The bird uses its tongue to keep the seed in place and manipulate it if necessary. The upper mandible has a concave groove running along its edge. The lower mandible has more of a sharp edge, like a knife. With the seed firmly in place, the finch bites down while moving its lower mandible back and forth in a sawing or slicing motion. The shell cracks and out pops the tasty kernel from the inside. The kernel gets scarfed down and the shell is tossed to the ground.

The next time you're near a bird feeder and there are some finches around, try to watch them cracking seeds this way. It happens really fast. The sizes and shapes of finch beaks correspond with the types of seeds they eat most often. Some have longer pointy bills, other have big thick bills, and so on. The thickest bills belong to the 15 finch species we call gross beaks. This word comes from French and means fat beak. We have the evening gross beak, Japanese gross beak, and pine gross beak to name a few species.

The 15 gross beak finches are not all in the same genus, which means they aren't all close related, because it turns out that big fat beaks have evolved independently more than once within the fringility family. Finches with fatter bills can bite with more force so they can crack the shells of bigger seeds. Sometimes small finches like siskins and red poles will hang out around a big burly gross beak to see if they can score any table scraps. The little birds can't crack the big seeds themselves, so they wait for the gross beak to do it for them. There are some splendid examples of beak specialization in the Finch family. The Hawaiian honey creepers are the most extreme with all sorts of outlandish bill shapes that

correspond to their respective diets. Some slurp up flower nectar, others catch insects, etc. Compared to most finches, these honey creepers are in a league of their own in terms of dietary specialization. But just as spectacular are the six cross-bill species found in North America and Eurasia. These finches, all in the genus Loxia, have amazing bills that are unique in the world of birds. The curving tips of their upper and lower mandibles cross each other in the horizontal dimension. It's sort of like when you wish for luck and cross your fingers, when your middle finger overlaps your index finger.

No other birds in the world have beaks like this. Cross-bill beaks are designed for eating the seeds of coniferous trees, such as pine, larch, and spruce. A cross-bill twists its lower mandible to pry apart the scales on a cone. Then it uses its tongue to grab the seed tucked between the scales. The different cross-bill species specialize in eating from different types of cones. For example, the white-winged crossbill, also known as the two-barred crossbill, eats mostly the seeds of larches. The Cassia crossbill, on the other hand, specializes on Lodgepole Pine. One feature shared by most finches is that they feed while climbing around like little apes in bushes, trees, or on flower stalks.

This is in contrast to, say, sparrows, who tend to forage for seeds on the grass. round. Finches have short legs and strong, grippy feet. These are great for clinging to plants, even while hanging upside down. Crossbills clamber around in the needles of conifer trees. Euphonias gobble mistletoe seeds in the branches of tropical hardwoods, and goldfinches ride on the stems of swaying sunflowers and thistles. There's a lot more I could say about the diets of finches and how they eat. But alas, we aren't getting any younger and there are some other important topics to cover today. When it comes to their annual movements across the seasons, many finches don't show the strong migratory behavior we see in other familiar songbirds like

warblers. Finches are more often facultative migrants, flying long. long distances only when their food supplies run thin. Many finches are resident birds, while others are nomadic. Nomadic species like the evening gross beaks, crossbills, and siskins wander around in flocks searching for their sporadically available food sources. This brings us to the concept of eruption, not eruption like a volcano, but eruption with an eye. This is a form of irregular migration where birds show up in places we don't normally see them. The word erupt comes from Latin, meaning to break into or burst into.

In northern winters, seed crops or other bird foods are scarce in some years. Some birds like finches and snowy owls move south in droves to find food. Bam! Irruption! These birds come burst. onto the scene in lower latitudes and birders across the land rejoice. Birders love eruptions. An outstanding eruption has actually occurred this winter here in North America. Trees in the boreal forests of Canada and Alaska have failed to produce many seeds.

This happens every few years. It's a sort of boom and bust cycle. The dearth of seeds this winter has forced all of our northern finches to fly southward into the U.S. Ornithologists are calling this event a super flight, because so many species are involved. This eruption includes common red poles, hoary red poles, evening gross beaks, pine siskins, red crossbills, white-winged crossbills, and purple finches. Wowza! Better keep a few metric tons of bird seed on hand this winter. Our last topic is breeding.

How do finches replicate to make little copies of themselves? Finch pairs are monogamous, and both parents take care of the young. Male finches are often more brightly colored than females. In many species like the housefinch, the red or orange feather colors come from carotenoid compounds found in seeds. The redder a male house finch is, the more high-quality food he's probably eating. Female house finches prefer to shack up with the most brightly colored males. Ornithologists think that this is an example of plumage color representing an honest signal of the male's fitness. By choosing a bright red male, a female is choosing a healthy partner with good genes.

The typical finches' nest is a classic cup-shaped structure. However, in their continual efforts to stand out from the crowd, euphonias and chlorophonias make dome-shaped nests with a little side entrance. But in all finches, the female is the one who builds the nest and incubates the eggs. But dad sticks around to help feed the chicks. The nests of house finches in Mexico City are often littered with cigarette butts. What's up with that? Have these birds taken up a nasty habit as part of their jaded urban lifestyle?

There's an actual research paper about this phenomenon published in the Journal of Avian Biology. What happens is female finches collect cigarette butts off the street, they tear them up, and line their nests with the fibers. The researchers in this study figured out that the cigarette butts are added by the birds as a response to the presence of ticks, which are nest parasites. Apparently, the nicotine and other toxic chemicals in cigarettes repel the ticks. Crazy, huh? See, now you don't have to feel bad about tossing your cigarette butt on the sidewalk. Just kidding, you should definitely feel bad. Don't do that.

And don't smoke. It's bad for you. Nessling finches fledge and pop out of their nests after 10 days to a month, depending on the species. The young birds are cared for by mom and dad for a couple weeks, at least for most temperate species. Some Hawaiian honeycreepers take care of their offspring for up to a year. Once they're on their own, finches face the many challenges of being a small songbird. They have to find enough food, endure seasons of harsh weather, and avoid. avoid predators and diseases. Most won't survive more than a few years. But a lucky

finch can live for over 10 years and leave behind a handful of offspring. That's at least 10 years to crack countless seeds, destroy fruit orchards, overwhelm your bird feeders, collect cigarette butts, or sweep across the land in a horde of tiny feathered barbarians. To all the true finches of the family fringility, all you legit finches, to you I say, good luck, and may you find all the seeds or berries or bugs that your tiny hearts desire. Thanks a lot for listening, and for your interest in these wonderful little birds. I really appreciate you being here to learn with me. I hope this episode helped you understand finches a little better and helped you appreciate them even more than you already did.

If you haven't subscribed to the Science of Birds podcast, you should totally do that because there is so much more to learn about birds. So much. If you have something you'd like to say about the show or if you have a question, shoot me an email. The address is Ivan at Science of Birds.com. You can check out the show notes for this episode, which is number 22, on the Science of Birds website, science ofbirds.com. This is Ivan Philipson. Thanks again, and I'll catch you next time. Cheers.