The Science of Birds - Hawks, Eagles, and Kites

Episode Date: June 1, 2026

👕 Bird Merch —  Get yourself some bird shirts!~~~This is Episode 134. Ivan takes on one of the most iconic bird families in the avian world: Accipitridae—the hawks, eagles, kites, buzzards, harriers, and Old World Vultures. It's a massive and diverse group with no good nickname, though Ivan has a few suggestions.The episode covers the key traits that make these birds such formidable predators—from their hooked bills and locking talons to the bony "brow ridge" that gives them their signature scowl. Ivan also digs into the family's staggering diversity: 249 species across 73 genera.Along the way, there's some evolutionary biology, a Weirdo Alert, and a look at the ancient giant that makes today's largest eagles seem modest by comparison.Links of InterestHaast's Eagle episode of the Blurbs podcastHarpy Eagle video in Spanish, by Alberto Lobato [VIDEO]Wild Latitudes: Worldwide birding and nature tours.Link to this episode on the Science of Birds websiteSupport the show

Hello and welcome. This is the Science of Birds. I am your host, Ivan Philipson. The Science of Birds podcast is a lighthearted exploration of bird biology for lifelong learners. This is episode 134, and it is all about birds in the family, excipitrity. This is the family of the hawks, eagles, and kites. But the family excipitrity also includes buzzes, hazards, harriers, and all the old-world vultures.

For the most part, these are diurnal predators with excellent binocular vision. I do wish there was a concise term or name for this family. You know, instead of having to say, Excipitriety is the family of hawks, eagles, and kites, and buzzards, harriers, old-world vultures, and a few other randoh raptors. Maybe we could name this group something like, like the hoggles or the hawserd vulgels.

I don't know. I suppose we can just say excipitrids, but that one doesn't roll off the tongue too easily. And saying birds in the family excipitrity are called excipatrids feels a bit circular, like saying a true fact is a fact that is true. Now at this point maybe you are thinking, hey Ivan, you dummy, can't we just use raptors

or birds of prey to describe these birds? And yes, but the problem is, some other birds in totally different families are also called raptors. We're talking birds like falcons, the osprey, and the secretary bird. And sometimes we call owls raptors too. And none of these birds are in the family ex-hypitri. There was actually a paper published in 2019

in the Journal of Raptor Research titled, defining raptors and birds of prey. The authors of that paper came up with a definition for both raptor and bird of prey. And here it is. Raptors are all species within orders that evolved from a raptorial land bird lineage and have mostly maintained that lifestyle. And the word order is the taxonomic order, as in, you know, class, order, family species. Under this modern definition, the following orders are classified as both raptors and birds of prey. So these are orders. Excipitreformis, which is the Hawks, Eagles, Old World vultures, and the Osprey family and Secretary Bird family. And then the next order is cathartiformes, which is made up of the New World vultures, and then falconiformes, falcons and so on,

Karakaras, stridiformis, the owls, okay, so here we are calling them raptors. And lastly, Karayamaformis, which is the Sariamas of South America. So those orders are the birds we consider raptors or birds of prey. Now, as for what technically separates a hawk from an eagle, from a kite, right? Some more terminology here. Well, these words are just common names that don't always reflect any underlying genetic relationship. I mean, there's no one genus that contains all the hawks or all the kites. Likewise for eagle, because, for example, the term eagle refers to various raptors that aren't necessarily close relatives, but are generally characterized by their big and beefy size and tendency to eat larger prey, like mid-sized mammals and big birds. Within the accipitrity family

tree, birds we call eagles are scattered across 20 genera, 20 branches of the tree, with hawk and kite lineages sandwiched between the eagle branches. In other words, there was no single eagle ancestor that eventually diversified into all the eagles we know today. So eagle is really just a name we like to use for birds that are bigger than most other members of their family, as long as you ignore vultures. In any case, hawks and eagles have captured human imagination

for thousands of years, Because they soar incredibly high and have razor-sharp eyesight, many cultures have viewed them as totems or symbols of strength, freedom, and divine power. Instead of just seeing them as animals, both ancient and modern societies have often treated these powerful birds as living links between Earth and the heavens. For example, for many Native American tribes, eagles are considered sacred messengers that carry prayers, to the Creator. In Mongolia, nomadic hunters have a centuries-old tradition of using live golden eagles as hunting companions, and the wedge-tailed eagle in Australia is important to many indigenous Australian people, particularly the Kulin nation of southeastern Australia. In their dreaming stories, the eagle is an ancestral creator spirit who shaped the landscape, created human beings, and so on.

In ancient Rome, the eagle was the ultimate. symbol of the empire's authority. A similar association with national power is also visible in Mexico, where the flag features an eagle perched on a cactus, which is a tribute to an ancient Aztec legend. In fact, about eight countries today have a flag with an eagle on it. And even though the bald eagle isn't on our flag, this bird is a major national symbol of the United States. The point is, humans in general seem to really admire and revere birds in the family accipitrity, especially eagles and hawks. Maybe you are such a human.

If so, then this podcast episode should be right up your alley. I've put off talking about this family for a long time. We're getting up to almost six years of the podcast, and I'm finally getting to this family. The day has come at last, so let's get into it. As is our custom, we'll start by considering what these birds look and sound like. The overall body and wing shape among species in the family excipitrity varies to some extent, based upon what a species eats and how it flies.

For example, hawks in the genus Beautio, as well as vultures and many eagles, tend to have stocky bodies and broad wings for languid soaring. Meanwhile, kites tend to be more slender with long pointed wings which are great for hovering flight. The beak or bill of an excipitrid is one of its most iconic raptorial features. These birds have strongly hooked bills used for tearing prey apart. Unlike mammalian predators that have mouths bristling with pointy teeth, a hawk or eagle has the equivalent of just one curved fang. The base of the upper bill is covered by a fleshy membrane called the seer, spelled C-E-R-E, which is where the nostrils are located.

Another feature common to most of the birds in this family is the supra-orbital ridge. This is a bony projection over the eye socket. It's sort of like a brow ridge, and for many species it makes the bird look like it has a scowling or fierce expression. I would say it should be called resting eagle face. But it isn't just when the bird is relaxed and resting. It's like all the time. It's a 24-7 angry face. The supraorbital ridge serves two primary functions for diurnal raptors.

First, it reduces glare. The most important function of this ridge is to act like the brim of a baseball cap. By physically shading the eye from overhead sunlight, it reduces glare and perhaps enhances visual contrast. This is an essential adaptation for visual predators that need to spot camouflaged or moving prey from high altitudes or against bright skies. And the second function is mechanical protection. Excipitrids often chase their prey in hazardous environments or they tackle prey that fights back. For a bird-eating species like a Cooper's Hawk or Northern Goss Hawk, these birds zoom at high speeds through dense forest canopies. The protruding supraorbital ridge helps shield their delicate eyes from twigs and leaves.

Similarly, when a hawk or eagle is wrestling on the ground with prey that has claws and pointy teeth, the recessed positioning of the eye helps protected from physical trauma. Another iconic trait of most birds in this family is, of course, their clawed toes, their talons. Excipitrids have anisadactal feet, which is the arrangement with three toes and facing forward and one backward. Digit number one, which is the halux, which is like the thumb, and it faces backward, and then there's digit two, the inner forward-facing toe, well, digits one and two sport the largest most wickedly curved talons. Together they act like a pincor to puncture and crush prey. The foot also has this cool tendon locking mechanism. There are ratchet-like ridges

on each toe tendon that lock into corresponding grooves on an internal sheath that the tendon slides through. This allows the bird to maintain a crushing grip indefinitely without burning energy with its muscles. It has to consciously release its grip. It's almost like you can imagine a zip tie. You know, when you close a zip tie, there are those little ridges, so it's a little bit like that. And this is the opposite of how our hands work, right? Humans have to consciously tighten our grip. For us to let go, we just have to relax. So again, the opposite of what these birds do. Looking at all the species in the family ex-Hipatrity, which is the smallest? Well, that would be a tie between the pearl kite of the neotropics and the little sparrowhawk in sub-Saharan Africa.

These little cuties are both about nine inches long overall, which is about 23 centimeters. The largest species in the family, and certainly the most massive is the Scenarius vulture, which lives in Europe, northern Africa, and Asia. This monster of a raptor measures up to 44 inches or 112 centimeters long, and it can weigh up to 27 pounds, or 12.5 kilograms. Now that, of course, is a vulture, but what about the non-vulchers? Which eagle is the biggest eagle? Well, the largest and most powerful eagle species are Maybe it's a tie between Harpy Eagle, Philippine Eagle, and Stellars Sea Eagle. The Harpy Eagle, for example, is up to 42 inches long, which is 107 centimeters. Most species in the family Excipitrity show sexual dimorphism.

Males and females are different sizes. Now, in many other types of birds, when there is sexual dimorphism, the male is the larger sex. But a key feature of this family is that the female is. the larger one. So the maximum sizes I was just giving you were for females. Plumage coloration in hawks, eagles, kites, and friends is almost always some combination of white, gray, buff, or orangish, brown, and black. Most species are darker on top and paler below, and this two-tone look is for camouflage. The amount of bare skin on the face varies among species as, as a little bit of two-tone look is for camouflage. The amount of bare skin on the face varies among species as well as its color. It's often

yellow or orangish red, black, or grayish blue. Some species have crest feathers on the head. Examples include the black baza, mountain hawk eagle, and the long crested eagle. But most of the old world vultures, of course, have bare heads with not so many feathers. This is an adaptation for hygiene while feeding on carrion. You don't want to have feathers on your face when you tend to stick that face into the bloody, gooey, gross carcasses of dead mammals. Well, gross for us, not so gross for them. Let's move on to talk about the sounds these birds make. Vocalizations are used for establishing territories, warning off rivals, and staying in touch with mates. The voices of accipitrids aren't what most of us would call musical or necessarily pleasant, but they tend to be in the category of growling,

cawing, hissing, or even sort of quacking. Let's listen to a few. The first example here is probably the most iconic raptor sound ever, if not one of the most iconic bird sounds ever. No, that was not an eagle, but I bet you already knew that. Since you're a listener of this podcast, I can assume you are both intelligent and knowledgeable. So you know that this sound is in fact the call of the red-tailed hawk, Beautio-jamakensis. And FYI, if you didn't know,

episode 79 of this podcast is all about that species. Next up, we have the call of the bald eagle, which sounds quite different from the red-tailed hawk. Another familiar North American species in this family is Cooper's Hawk, Astor Kuperi. Now in case that scientific name, Astor Kuperi sounds wrong to you, I should tell you that until fairly recently this bird was in the genus Accipator, spelled A-C-C-I-P-I-T-E-R. Aster is spelled A-S-T-U-R. But ornithologists have recently agreed that, based on genetic relationships revealed by DNA, Cooper's Hawk is actually in the genus Aster.

and we'll talk a little more about that later. Anyway, here's a Cooper's Hawk recorded in Minnesota. Moving south into the neotropical region, we have a hook-billed kite, Condro-Hirax Uncinnatus, recorded in Ecuador. Also in the neotropics, we have one of the largest eagle species, the harpy eagle. This too was recorded in Ecuador. Our next example is the black kite, Milvis Migrens,

a very familiar and common species across almost the entire old world, Europe, Africa, Asia, and Australia. And lastly, here's an African Harrier Hawk, recorded in South Africa. Okay, now we'll move on to talk about diversity within the family Excipititi, as well as the geographic distribution of the family, habitats, and all that. But first, let's quickly look at the etymology of the name Excipatrity. This one is pretty straightforward. It's derived from the Latin word excipator, which means hawk. As I mentioned earlier, the family excipatriti is within the avian order excipatiformis. So it's within this order that we need to look for the families that are most closely related to excipitrity.

And these are pandionity and sagittariadi, the families of the Ospre and secretary bird, respectively. Both are monotypic families, meaning they each contain just one species. The New World vultures share some features with the birds we're talking about today, some resemblances, but they are only distantly related, and they belong to their own order, cathartiformis. Falcons, kestrels, and kharakaras look, at least superficially like they should be in the family excipitriti, but they belong to the family falconidy, which is, quite distantly related to our hawks, eagles, and kites. Many of the raptorial features shared by falcons and excipitrids are the results of convergent evolution. These two groups of birds

share similar lifestyles as predators, so natural selection independently shaped them to have similar adaptations like hooked bills and strong talons. There are 249 species in the family exypotrit and these are divided among 73 genera. So this is a large and diverse group. As we look at the phylogenetic or evolutionary tree for this family, we see that it appears to be split into some distinct branches, major branches. Ornithologists have designated 12 of these branches as sub-families. For example, Alanini is the most ancient branch slash sub-family within the tree. Known as elenine or small kites, these are small, lightly built birds with long pointed wings. We're talking species like the pearl kite, remember that's the smallest one, as well as the

scissor-tailed kite, white-tailed kite, and black-winged kite. Budionini is the most diverse of the 12 sub-families. Among others, it includes hawks and buzzards in the genus Budio, as well as the sea and fish eagles. and the red and black kites. This sub-family, Buteotony, has about 80 species in it. Again, there are 73 genera. The most species-rich genera in the family are Tachyspiza with 27 species,

Boutio with 27 species, Circus with 16 species, those are the Harriers, and Aquila with 11 species. The genus Tachis Pisa, which has, is a tide for having the most species, was recently resurrected. Sort of like a mummy or a vampire, this genus was alive and kicking a long time ago. And this word comes from ancient Greek and it translates as swift hawk. Tachysa means swift hawk. And then as bird taxonomy changed over the

years and got updated, Tachyspiza was no longer used. It was killed off, so to speak, murdered by cold-hearted ornithologists. Tachisipiza returned from the grave in 2024 when ornithologists conducted and published a comprehensive molecular phylogenetic study of birds in the genus Excipator. Before that study, the genus Excipator was mega-diverse, with about 50 species in it.

Excipator was sort of a catch-all, junk-drawer genus for forest-dwelling hawks from around the world, But that 2024 phylogenetic study found that the genus was not monophyletic, meaning those 50 or so species did not all descend from a single excipator ancestor. So the researchers rearranged the taxonomy and moved the majority of the old excipator species into five new or resurrected genera, such as tachysa and Aster. Remember that Astor, A-S-T-U-R, is now the genus for Cooper's Hawk, and it's also the genus for the American Gosshawk and Eurasian Gosshawk.

So Aster is also a spooky resurrected genus that has returned from the dead, to strike terror into the heart of any birder who stubbornly refuses to accept the fact that Cooper's Hawk is no longer an excipiter. So today, the genus Excipiter that used to have 50 species, now it just has six species. But the Sharp Shindhawk is still in this genus, as is the Eurasian Sparrowhawk. So maybe you're putting two and two together here, because if you're an American birder or bird enthusiast, you might be shocked to learn that despite their very similar appearances, Cooper's hawk and the Sharp Shinned Hawk are not each other's closest relative. They're in two different genera, astor and occipiter, respectively. And get this, those two genera are not even

sister genera. So Cooper's Hawk and the Sharp Shindhawk, birds that look so similar that they're a serious ID challenge for many North American birders, those two species are surprisingly far apart on their family tree. And this fascinating ornithological factoid was only discovered a few years ago, which is pretty cool stuff if you ask me. I also want to point out that there are quite a few monotypic genera in this family. 36, to be exact. A monotypic genus has just one species in it. For example, the genus Rupornis contains only one species,

the roadside hawk, Rupornis Magnarostris. This smallish hawk is widespread across the tropical parts of Central and South America. And you have to wonder why this species evolved to live only along the sides of roads. And roads haven't even been around that long, so the roadside hawk had to have evolved very rapidly, like in the last 200 years. And this has me thinking what other species might evolve like this to thrive in our human-made environments. I can imagine a few. How about amusement park hawk?

Landfill Lamergeyer, golf course gosshawk. Inner City Eagle or Strip Mall Sparrowhawk. And in case you're new to the podcast and you can't tell, I am just kidding around, like I do. Because the roadside hawk did not evolve to live specifically along our roads. No, its preferred habitat is forest edges. And that habitat just happens to be common along roads. Birds in the family Exhibitrity are distributed all across the planet. They're found in the Americas, Europe, Africa, Asia, Australia, and you'll find one species or another of, let me try this out, one species or another of hoggle or buzite on islands too.

Nah, that doesn't work. Anyway, we're talking about Madagascar, Indonesia, New Zealand, Arctic islands, little islands way out in the tropical Pacific and so on. These birds are all over the place. So this is a cosmopolitan bird family. But there is one very large landmass that is treated as a no man's land, or rather no hawks land, a place so cold and dark and distant from any kind of joy that birds in the family excipitriti, in their wisdom, avoid it at all costs.

That place is none other than Antarctica. Yes, there are some birds in Antarctica, penguins, and sun. gulahs and sheathbills and whatnot, but there are no hawks, eagles, kites, buzzards, or vultures among them. Okay, I'm going to give a quick rundown of the most common excipitrids on each of the continents. And this info is based on observations reported on I-naturalist, so the following birds are the species most commonly observed on the I-naturalist platform slash app. There are 61 species in North America, the most common of which are the red-tailed hawk, bald eagle, red-shouldered hawk,

Cooper's hawk, northern harrier, and Swainson's hawk. South America has 58 species with the most common being roadside hawk, Harris's hawk, snail kite, variable hawk, and savanna hawk. Europe has 48 species with the common buzzard, black kite, western marsh harrier, red kite, and Eurasian sparrow hawk as the most common. Africa has 90 species, the most common being African fish eagle, black kite, white-backed vulture, tawny eagle, and black-winged kite. Asia takes the trophy with the most species at 99. The most common are black kite, crested serpent eagle, bromony kite, oriental honey buzzard, and western marsh harrier.

And then Australia has 18 species, the most common of which are the wedge-tailed eagle, whistling kite, white-bellied sea eagle, black-shouldered kite, and black kite. Notice how on several continents the black kite is one of the most common. Weirdo alert. Weirdo alert. Uh-oh, look out. We've got a weirdo in the house. Now, as I mentioned, all of the old-world vultures are in the family excipitriety. They're all sort of weird, and among those vultures, I would probably say that the bearded vulture, also known as the Lamergeier, is the weirdest weirdo of the bunch.

But I'd like to do an entire podcast episode on the bearded vulture someday. So, for today's weirdo alert, we're going instead with the palm nut vulture, Gipohyrax Angolanus. In terms of appearance, the palm nut vulture isn't necessarily all that weird looking, at least for a vulture. It's one of the smallest of the old world. vulture species. It has a body that's mostly white, contrasted by black sections on the wings and tail. One of its most recognizable features is a patch of bare red skin around each eye. It has a

powerful hooked beak, a small head, and a relatively long neck. The palm nut vulture is the only member of its genus, Gipohyrax, meaning it has no close living relatives. So Gipohyrax is one of those monotypic genera I was talking about. You find these birds throughout sub-Saharan Africa. They live primarily in tropical forests and savannas, almost always near a source of water like a river, lake, or mangrove swamp. Their lives are closely tied to oil palm trees and raffia palms. Because they are fairly approachable and not all that shy, palm nut vultures are often seen near human settlements. And they even hang out on the lawns of hotels. hotels in some popular tourist areas. Now, you might be wondering, well, what's so weird about all of that?

Not much. But here's the thing. In an entire family of bloodthirsty carnivores and meat-gulping scavengers, the palm nut vulture stands alone in having a mostly plant-based diet. This bird is a frugivore. It gets more than 60% of its food from the fleshy husks of palm fruits. And for young palm nut vultures, fruit can make up as much as 90% of their diet. Now, that said, these birds do eat some animal material, too. When they aren't eating fruit, they hunt for small creatures like insects, snails, crabs, fish, and frogs. Palm Nut vultures perch in palm trees, and they spend about 60% of their waking hours eating fruit. Fruit is plucked with the bill, then it's held in the feet while the bird pulls apart and swallows the fleshy, savory bits.

And if any other frugivores like hornbills or monkeys come poking around, a palm-nut vulture will go berserk and go on the attack to protect its precious food supply. And you know, it's too bad there aren't some other frugivorous raptors in the family excipitriety. Then we might have some fun species like the banana kite, mango hawk, blueberry buzzard, strawberry harrier, and so on. Many species in the family excipitrity are long-distance migrants. These birds primarily fly during the day and often gather in large groups as they funnel through narrow land crossing like itthmuses or along peninsulas. You know I love that word, itthmus. It's always fun to say.

One famous example is Swainson's Hawk, Beautio Swainsonai. These birds breed in North America's temperate zone, then migrate in the fall down to Southern South America. That's a journey of over 6,000 miles or 10,000 kilometers in each direction. As migrating Swainson's hawks are funneled through Central America, their numbers get concentrated. In October and November, nearly 350,000 Swainson's hawks have been recorded passing a single location in Panama City. Ornithologists have suggested that migratory behavior evolved independently multiple times in the family exhipitrity, as birds expanded from tropical regions into the northern latitudes. There are three primary migratory routes or highways used by these birds.

One links north and South America, and that's like what the Swainson's Hawk uses. There's another between Europe and Africa, and there's one that spans the north. north and south parts of Asia. Birds using the American and European-African roots face dangerous obstacles like vast deserts and open seas that can lead to high death rates during the journey. On the other hand, the Asian routes are often considered less hazardous because the landscape changes more gradually without as many extreme physical barriers. An example of a long-distance migrant for the Europe-Africa route is the European Honeybuzzard. Pernus Apivorous. This species breeds in Europe and migrates to sub-Saharan Africa for the winter.

In Asia, an example is the Japanese Sparohawk, Tachisipa, Gularis, a long-distance migrant that breeds in Japan and elsewhere in Asia's far east. It winters in places like the Philippines, Borneo, and other islands in the Malay Archipelago. As a group, birds in the family Excipitriety are found in virtually all terrestrial habitats, including every kind of forest, as well as grasslands, savannas, deserts, alpine areas, and Arctic tundra. In many of these ecosystems, Acipitrid raptors act as top predators, so they play very important roles in the food webs, or the food chains of the habitats where they live. We'll talk more about what these birds eat a little later. It's time to talk about Ivan's favorite subject in the realm of biology.

then that is evolution. This family is thought to have an origin in Africa. So that would be where the common ancestor of the family excipitrity lived. That single species split off to form its own lineage between roughly 60 and 50 million years ago. So that's when the split occurred that led to the lineages of the Osprey and secretary bird on one side and excipitrity on the other. Our ancestral proto-hawk eagle diversified into more and more species during the oligocene and myocene epochs,

so between about 30 to 5 million years ago. Those 12 branches, those sub-families, came into existence along the way. A few other interesting things related to evolution that I want to mention. There are 16 old-world vulture species, but their vultureine traits did not. evolve just once in the family excipitrity. Because old-world vultures belong to two separate lineages. One lineage is the sub-family, Jepetani, which includes our weird friend, the palm-nut vulture, as well as the bearded and Egyptian vultures. The more typical vultures all belong to the second lineage, which is the sub-family Egyptianee. That's a little confusing. One lineage is the sub-family

Gipitani and the other is Egyptianee. Good luck with that. If you see them written out, they look very different. The first one begins with a G, the second one begins with an A. So anyway, I think it's cool that vulture lifestyle and appearance evolved not just once in this family, but twice, independently. And remember that vultures in the new world, like the Turkey vulture, black vulture, Andean condor, those are all in a totally different family, cathartity. and a different order, and so they too evolved their lifestyle and traits independently. And the last nugget of evolution lore I want to touch on briefly has to do with an extinct species. Haast's eagle, hyraedis Mori.

Haast is spelled H-A-A-A-S-T. Host's eagle was, that we know of, the largest eagle ever. This gargantuan raptor lived on the South Island of New Zealand. And it went extinct not that long ago, only around the year 1445. Large females were significantly bigger than males, and they weighed up to 40 pounds. That's almost double the weight of the largest eagles alive today. Despite its great weight, it had a relatively short wingspan of about 8 to 10 feet, or 2.5 to 3 meters. Ornithologists think these shorter, broader wings were an adaptation that allowed the

eagle to fly and maneuver through dense forests. Amazingly, DNA testing has shown that the closest living relative of Haast's eagle is, ironically, the Little Eagle, Hiatus Morphnoides. The Little Eagle is, as the name suggests, much smaller, at only about 2.2 pounds or one kilogram for females. Little Eagles are found across Australia today. Host's Eagle appears to have evolved from an ancestral little eagle, or something like it, that colonized New Zealand sometime between 1.8 million and 700,000 years ago. Now, if that's how it happened, then Host's Eagle represents the most dramatic and fastest evolutionary increase in weight of any known vertebrate species, increasing 10 to 15 times in mass in less than 2 million years.

As the top predator in New Zealand, Haast's eagle filled a role similar to that of a lion or a wolf on other continents. Its primary food source was Moa, giant flightless birds that could weigh up to 440 pounds or 200 kilos. To take down such large prey, Haast's eagle used incredibly powerful talons, with a rear claw on the halics reaching up to 4.5 inches long. After the first humans, the Maori arrived in New Zealand, they ended up hunting the various Moa species to extinction. And at the same time, they destroyed the forest habitat that the eagles depended on. So without its main food source and its habitat, Host's eagle vanished shortly after the last Moa.

The bird remains today a part of Maori history through rock art and legends of the Poikai, a terrifying giant bird powerful enough to kill a human. And for all we know, Host's Eagles actually did occasionally kill young people, like kids. It's possible. And if you'd like to learn more about the amazing Hosts Eagle, you should check out a recent episode of the Blurbs podcast, hosted by Matt Ross down in New Zealand.

I'll put a link to Matt's Host's Eagle episode in the show notes. With regard to their conservation, how are the 249 species in this family doing? Well, 30 of them are in the near-threatened category on the IUCN's red list. 21 species are classified as vulnerable, 21 are endangered, and 12 are in the worst category which is critically endangered. Eight of those 12 critically endangered species are actually vultures, and there are two more more vultures in the endangered category. So why are so many vultures in trouble? Well, many of them are facing extinction because of a combination of human activity and their own natural biology.

The most devastating blow came from a common livestock drug called dichlofenac, which is extremely poisonous to vultures and caused populations in parts of Asia to crash by over 99%. Vultures get poisoned when they eat livestock carcasses that are contaminated with dichlofenac. Beyond poisoning, these birds are losing the specific forests and open spaces they need to live, as land is cleared for mining and city expansion. Their long-distance migrations are also incredibly dangerous. Research shows that young vultures are much more likely to die during these journeys while trying to cross massive obstacles like the Sahara Desert.

Finally, vultures are slow to bounce back from these losses because they have a low reproductive rate. A mated pair of vultures raises only one egg at a time, and each bird takes several years to reach adulthood. This makes it nearly impossible for their numbers to recover as fast as they are disappearing. Habitat destruction is a major threat, not just to vultures but to many birds in the family accipitrity, and generally birds around the world, and in the case of accipitrity, they are sometimes persecuted by humans as well. Only one species in this family

was driven to extinction in the last 500 years or so. Well, that we know of anyway. That species is the Bermuda Hawk, Bermudio avivores. This bird lived, as you might guess, in the Bermuda archipelago, in the Atlantic Ocean, about 650 miles, or 1,000 kilometers.

off the east coast of North America. The Bermuda hawk is assigned to its own genus, Bermutio, which is a portmanteau or sort of a mashup of the words Bermuda and the genus name Boutio. Bermuda plus Boutio equals Bermudio. And I, Ivan, strongly approve of this situation. Anyway, we don't really know what this bird looked like since there aren't many records. We don't have any photos on Instagram of this bird because it was driven to extinction by the early 1600s. The Bermuda Hawks extinction was likely caused by a combination of factors following European settlement in the 17th century,

including habitat loss from large-scale burning and deforestation to the introduction of invasive species like feral pigs and possibly hunting for food. Now let's talk about what these apex avian predators eat. The family excipitrity shows a wide range of dietary habits, from extreme specialization on single types of prey to highly generalized opportunistic predation. While almost all members are carnivorous, their specific diets can be divided into three broad categories, vertebrate eaters, and scavengers or weirdo specialists. And each of these broad categories can be broken into smaller subcategories. So starting with the vertebrate eaters, first up we have the mammal eater subcategory. Many groups, including Harriers and Budia-9 hawks, specialize in small

mammals like rodents and lagamores, aka rabbits. Meanwhile, powerful booted eagles in the subfamily equilony can hunt much larger prey. The next subcategory is bird eaters, accipiter hawks and many other species in the subfamily excipatrini are primarily adapted for hunting other birds. They often use agility to ambush small birds in dense vegetation. And then we have the subcategory of fish eaters. Sea and fish eagles, which are birds in the genera Haleedis and Icteophaga, primarily prefer fish, which can constitute over 90% of their diet. There's a subcategory for reptile and amphibian eaters.

Snakes are the primary prey for snake eagles and serpent eagles, and many other excipitrids hunt lizards or frogs opportunistically. And the last subcategory of vertebrate eaters is, believe it or not, bat eaters. There's the bat hawk, macarampus alcynes. I think that's how you say it, and that is a highly specialized aerial hunter that feeds almost exclusively on bats. Okay, so now we have the next broad category of invertebrate eaters. And here the first subcategory is insect eaters.

Several species, such as the honey buzzards in the genus Pernus, specialize in eating the larvae of social insects like wasps and bees. Others, like the pearl kite and scissor-tailed kite, focus on a variety of flying or tree-dwelling insects. Then we have the subcategory of sands. snail eaters. The snail kite, slender-build kite, and hook-build kite are specialists that consume snails, primarily apple snails, which are really big. And snails can be 50 to 95 percent of the diet of those birds. And amazingly, we have a crustacean eater subcategory. Some members of the genus

Budio-Galus, such as the Rufus Crabhawk, have evolved to specialize specifically on crabs. And our last broad category is the one that includes the scavengers as well as some specialized weirdos. That's my term, weirdos, that's not the technical term. The most diverse subcategory here is for the carrion feeders, the scavengers. Old World vultures are famous for specializing as scavengers, and they subsist primarily on the carcasses of large animals. But we have another specialist, another specialist, another substance, subcategory the bone marrow eaters. And this is primarily the bearded vulture, the lammergeyer, which has a unique diet consisting primarily of bone marrow, which it gets at by dropping large

bones from great heights to bust them open. Again, someday I'll do an episode on that species. It's a cool bird. Our next category is the egg eaters. I've talked before about one of my favorite birds, the Egyptian vulture, and it is known to actually use rocks as tools to to break open large ostrich eggs. There's a whole lot of slimy fat and protein inside of a single ostrich egg, so it's not surprising that a bird evolved to access that resource.

And then the last subcategory here is the fruit eaters. This is the one, of course, that includes our weirdo, the palm nut vulture, and our imaginary species like the mango hawk and blueberry buzzard. Most species in the family excipitrity are top-level predators, such that they themselves have few, if any, predators. These birds aren't in danger of being eaten by any other animals.

They are the danger. For example, small birds live in terror of bird-eating hawks. When the distinct silhouette of an aerial predator is spotted in flight, many small birds like chickadees, titmites, and sparrows instinctively emit a very specific high-pitched warning sound known as a seat call. S-E-E-T. This call typically registers around 7 to 9 kilohertz, and at these frequencies, the sound wave attenuates. It fades very quickly over distance. So it's incredibly hard for an incoming raptor to pinpoint the location of the bird who made that seat call. The sound warns other small birds in the area to

hit the deck, to dive for cover without giving away the caller's exact position to the hunting hawk. Other birds do this as well. They have their own specific calls for incoming predators. For example, I have chickens as pets and I know from observing them that they emit very specific calls when they see a raptor soaring overhead. They're eternally vigilant for fear of avian death from above. How do hawk's eagles and their excipitrid kin go about the business of breeding. Most species are monogamous with bi-parental care, although some show cooperative breeding or even polygyny.

Harris's hawk is an example of a cooperative breeding species, while the northern Harrier is an example of a species that, at least sometimes, displays, polygyny. And that's where one male is paired with multiple females. But the Galapagos Hawk, Budio Galapagopgoensis is the opposite. It's one of the very few polyandrous bird species, not just in this family, but period,

where multiple males help a single female raise a brood. Birds in this family show a variety of courtship behaviors. They call to each other, and pairs often perform acrobatic aerial displays involving rolling and diving. Eccipatrids are also known for being ferociously protective of the areas where they live and hunt. Before the nesting season even begins,

adult birds spend a significant amount of time patrolling their space to keep out other members of their own species or even other types of birds. And the size of these territories can be massive. For larger species like eagles, a single pair might control an area covering dozens of square miles to ensure they have enough room to hunt and find food for their young.

These birds have different ways of marking their territory depending on where they live. In open environments, they typically use aerial displays, flying prominently over the borders of their range to signal their ownership to others. But in thick forests where they can't really see each other all that well, they rely more on loud calls and vocalizations to warn intruders to stay away. And once a pair establishes a territory, they're often extremely loyal to it. They might return to the same nesting site for many years.

The nest is generally a large platform of sticks, which is built in a tree, on a cliff, or even on the ground, and it might be reused for decades by multiple breeding pairs with new material added each year. Species in this family typically have low reproductive rates. Clutch size ranges from one to six eggs and the eggs are typically laid at intervals rather than it all at once. Both the male and female usually contribute to nest construction and they share in incubation duties.

But once the eggs have hatched, the male typically provides food for the brooding female and nestlings. And remember that there's sexual dimorphism in this family where the female is larger than the male. And this division of labor during the breeding season, that might be the evolutionary cause, for that sexual dimorphism. Some ornithologists think that males were selected to be smaller and more agile because they're the ones out searching for food. Having smaller bodies, they also need fewer calories. Whereas the females having large bodies, they're just kind of staying on the nest with the chicks. Having a large body is good for providing heat for the chicks. It also being large is good to defend the nest from any interlopers, any predators. So those are some of the same.

some ideas behind why sexual dimorphism exists in this family. Now, because the eggs are laid at intervals, they hatch asynchronously. In other words, not all at once. This staggered asynchronous hatching often leads to the oldest nestlings being significantly larger than their slightly younger siblings. And that often results in fratricide or sybilicide, where the stronger older chicks out-compete or even directly murder their weaker nestmates. As a hypothetical example,

if the mango crop in India this year suffered from an abnormally cold growing season, things might get ugly in the nest of a mango hawk family. Big brother Mango Hawk might be eyeing his younger siblings, thinking to himself and plotting, if I just accidentally nudge these little runts over the edge of the nest, I'll have all those sweet sweet mango treats for myself. But this kind of thing really does happen to real species.

In lean years when there isn't enough food to feed a nest full of chicks, Ciblicide serves as a sort of dark insurance policy for the parents. At least one or two of the chicks might survive. But if it happens to be a boom year and there's lots of food, well, then maybe all of the chicks survive. In any case, after fledging, young birds remain dependent on mom and dad for a long time, compared to what we see in many other kinds of birds. Young hawks, eagles, and the like might hang out with their parents for more than a year.

Like many apex predators, accipitrids suffer from incredibly high juvenile mortality rates. Between 70% and 90% of these birds do not survive their first one or two years. because of starvation, accidents, and the steep learning curve of having to figure out how to hunt. Because of this, if you average out every single bird from birth, the statistical life expectancy is something like one to two years, which is pretty brutal. Now that said, sort of paradoxically, birds in this family are known for being exceptionally long-lived. And that's because as long as an excipitrid can manage to survive, the perils of its youth and reach breeding maturity, its expected lifespan then is much higher than

those one or two years. And across all the species in this family, lifespan tends to scale dramatically with body size, meaning larger birds live longer. So for example, small species like sharp-shinned hawks, sparrowhawks, they might live in the wild about three to five years with a maximum recorded lifespan of something like 15. Medium-sized species like red-tailed hawks, harriers, kites, they live eight to 20 years in the wild with a maximum of 25 to 30. And then large species, bald eagles, golden eagles,

old world vultures, they're going to live 15 to 30 years in the wild with a maximum of about 38. Lifespan scales with body size. And that, my friends, is our grand tour of the magnificent and fearsome family known as excipitrity. Sure, these birds might have 24-7 angry faces and they definitely aren't winning any singing competitions,

but they are beautiful and super cool. It's easy to see how they've captured the human imagination and have inspired us for thousands of years. They are the ultimate masters of the sky. I hope you enjoyed today's exploration of this family. I plan to make future episodes about individual species or genera. There are just so many cool birds in this group, and it'll be fun to learn about them with you.

I want to give a little shout out to Alberto Lobato for sharing his Harpy Eagle recording. Alberto has a Spanish-language birding YouTube channel called Chronicas del Chivisoyo Histories de Aves. He made a video about the Harpy Eagle, and I'll put a link to that in the show notes. I also want to thank my wonderful supporters on Patreon. As always, you folks are the ones who make this podcast a reality. You are the sine qua non of the Science of Birds. You are indispensable.

So I want to give a big welcome to the newest members of the Science of Birds community on Patreon. Casey Marie, D.L., Adrian Wolfe, Sarah Conley, Dave Last, and Marissa Jane. Thank you all very much for your support. you're awesome. If you would like to join the community and get some perks like behind the scenes posts by me and getting to vote in polls to choose episode topics, please check out my Patreon page over at patreon.com slash science of birds. And there's also a support-the-show link in the show notes on your podcast app.

And if you have something you'd like to share with me, please go ahead and shoot me an email. I can be slow to respond, but I really do try to get back to everyone. If you have a comment about the podcast you want to share, or maybe you want to tell me what subcategory your diet belongs to, for me, I suppose my subcategory would be something like herbivorous popcorn specialist. But yeah, if you want to email me, whatever you want to say, the email address to which you can write is Ivan at Scienceofbirds.com.

This, again, is episode 134. You can check out the show notes for the episode, along with some hand-selected photos of birds, I talked about today over on the Science of Birds website, Science of Birds.com. Don't forget to check out birdmerch.com if you want to get yourself some cool bird-related t-shirts designed by yours truly. And if you're interested in traveling to check out cool birds from various places around

the world, you can join me or one of my colleagues on a tour with wild latitudes. You can check out wild latitudes.com for that. I'm Ivan Philipson as always, and a fun fact about me, I am recording this episode in a new location, an undisclosed secret location, but I have moved. I've moved from the city of Portland out to the country. I'm back in the country again, surrounded by birds and trees and chickens, and it's pretty cool. So, yeah, hopefully this podcast sounds as good, if not better, than the studio or the setting I was recording it before, which was really just a little closet,

and this is basically just another little closet. But yeah, I moved, and so that is a fact about me, a true fact that is also a fact that is true, if you know what I'm saying. Thanks for being here, thanks for listening, thanks for your interest in birds and science and the beautiful world around us. I'll talk to you next time.

Peace.