The Science of Birds - New World Vultures

Episode Date: November 3, 2021

This episode is about the seven bird species in the family Cathartidae: the New World vultures and condors.This group includes species like the Turkey Vulture, Black Vulture, and Andean Condor.Among these birds are some that people celebrate, or even revere. But others tend to get ignored, disparaged, or at worst, persecuted. I guess you could say our relationship with New World Vultures has been… complicated.~~ Leave me a review using Podchaser ~~Support the show

Imagine wandering the vast landscapes of North America during the last Ice Age in the Pleistocene epic. The diversity and enormousness of the mammalian wildlife would blow your mind. There are giant sloths, mastodons, camels, American lions, horses, giant beavers, and so many more. These abundant Ice Age beasts add up to a lot of tasty meat walking around. Carnivores are killing to get at that meat, and prey animals are being killed for theirs. The body count is high. There are half-eaten carcasses all over the place, and every animal, whether a predator or prey, is going to keel over and die at some point, of old age if they're lucky.

So large, rotting mammal carcasses are an abundant resource during the Ice Ages, and where there's an abundant resource, no matter how disgusting it is, there's usually a group of animals that evolves to take advantage of it. This is where vultures come in. Vultures are the cleanup crew. No other vertebrate animals are so perfectly adapted to a life of scavenging for dead meat. These birds were around in North and South America for millions of years before the Ice Ages. But it was in that chilly time that vultures and condors really hit their stride.

The plethora of furry corpses sprinkled across the... the ice-aged tundra and grasslands, supported many species of scavenging birds. It was the golden age of the New World vulture. Without these birds, all those dead mammal bodies would have taken much longer to decompose. Nutrients would take longer to return to the soil. Meanwhile, things would get pretty stinky and foul. Diseases would end up spreading more easily among the living megafauna. Now, thousands of years later, vultures and condors in North and South America,

still act as our cleanup crew. They do their part to keep the world relatively clean and free of disease. These birds are integral members of almost every terrestrial ecosystem in the Western Hemisphere. And little known fact, the favorite song of vultures is Dead Bodies Everywhere, a track released in 1998 by the new metal band Corn. That's Corn with a K. Remember them?

These birds, the New World vultures, are in the biological family cathartadi. This name comes from the Greek word catharos, meaning pure, clean, free of shame. That's nice, isn't it? So at least the person who named the family cathartadi appreciated the value of vultures. Interestingly, catharos is also the origin of the name Catherine, and it's the name of a brand of Greek yogurt. So New World vultures are purifiers, cleansers. They deserve to be free of shame. Even if we humans don't always appreciate them, these carrion-eating specialists are amazing and beneficial to all of us.

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. This episode is about birds in the family, cathartody. These are the seven species of new world vultures and condors. This group includes birds like the turkey vulture, black vulture, and Andean condor. Vultures living in Africa, Europe, and elsewhere in the old world are not in the family cathartity. Those guys are a whole different ballgame. Old world vultures will get their own

episode too, don't you worry. But today, it's all about the unique lineage of new world vultures. Among these birds are some that people celebrate or even revere. But others tend to get ignored, disparaged, or at worst, persecuted. I guess you could say our relationship with New World Vultures has been complicated. I'm among those people who adore Vultures. Surprise, surprise, right? Hopefully you are too, or maybe I can help convert you. I'm stoked to be putting the spotlight on the New World Vulture family today, to celebrate their awesomeness and importance, and of course, to help you learn more about them. Starting off with the general characteristics of these birds.

At first glance, vultures and condors look something like hawks or eagles in terms of their overall shape. They range in size from medium to friggin' huge! Body lengths across the species range from about 22 to 52 inches. That's 55 to 130 centimeters. Wingspans range from 5 feet to a whopping 10.5 feet, or 165 to 320 centimeters. The smallest species, in terms of body length, wingspand, and weight is the lesser yellow-headed vulture, Cathartes Barovianus. This bird's body is about as long as that of a mallard duck.

However, the vulture has much longer and wider wings than the duck. The largest member of the family cathartidae is the Andean Condor, Volter Griffiths. This majestic beast is actually one of the biggest flying birds in the world. In fact, some people argue that no other flying bird is larger than the Andean condor, if you consider its combined wingspan and weight. In any case, this is a small. an enormous bird. It's the one that has a 10.5 foot wingspan. An Andean condor can weigh up to about 33 pounds or 15 kilograms. The California Condor, Jimnojip's Californianus, is almost the

same size as its South American counterpart. In North America, the California Condor is the champion. It's the biggest flying bird on the continent. The wings of cathartids are long and wide. superbly adapted for the passive soaring mode of flight. If you'd like to learn a bit more about soaring and the other flight modes, check out the previous episode of the podcast, episode 37, which was all about how birds fly. The rectangular, soaring wings of vultures and condors have large surface areas, and the birds don't weigh a whole heck of a lot compared to what you might expect looking at their broad wings. This means they have low, wing loading, and lots of aerodynamic lift.

A vulture can ride on a rising mass of warm air, in other words a thermal, to gain altitude without needing to flap its wings. So birds in this family excel at covering immense distances each day with relatively little effort. A vulture rides upward on a thermal, then glides slowly down to catch another thermal, and repeat. I grew up believing that when you see a group of vultures

circling around in the sky, that meant there was a dead or dying animal somewhere below them. This is basically a myth. Circling vultures are usually just taking the old thermal elevator up to higher altitudes. And there's no scientific evidence that I know of that backs up the idea that vultures can sense when a person or other animal is dying. Sure, once you're dead, a vulture will swoop on down to happily gobble up your guts. I mean, once it matter to you, you're dead, right? But there's no need to get nervous if you see some vultures flying overhead or perched in a nearby

tree. They aren't salivating in anticipation of your impending demise. They might wish you were dead for any number of reasons, but that's not the same thing as knowing that you're going to be dead soon. A group of vultures or hawks circling around in a thermal is sometimes referred to as a kettle, as if they were bubbles in a pot of boiling water. You usually see kettles of vultures in midday or in the afternoon, once the air has heated up enough from the sun to form rising thermals. Some clever turkey vultures and black vultures in Brazil have learned to make use of the artificial thermals rising off of power plants. Man-made thermals like this aren't really dependent on the sun or time of day. Research has shown that these vultures in

Brazil use artificial thermals at times of day when natural thermals aren't active. They seem to do whatever they can to minimize the amount of energy they spend while in flight. Now, this is all interesting and lovely, but we've been ignoring the elephant in the room. In discussing the appearance of vultures and condors, I probably should have started off with their crazy bald heads, don't you think? All the new world vultures have naked heads, with basically no feathers of any consequence. What feathers they do have on their heads are often short, hair-like bristles. Some people might say the unfethered heads of these birds make them look ugly or weird.

People are entitled to their opinions, of course, but keep in mind that a vulture probably thinks you look like a dirty old mop that magically came to life one day. Unless you happen to be bald. If you're bald, then that vulture is thinking you look pretty snazzy. Depending on which species of New World vulture you're looking at, the bare skin of its head may be black, red, orange, yellow, or even bluish, or some combination of these. The king vulture, Sarko Ramfus Papa, wins the award for having the most colorful head. This awesome bird lives across most of Central and South America. The skin on its head and neck is a wild combination of orange, yellow, red,

purple, black, and gray. The king vulture's striking visage is further enhanced by its big eyes with their piercing white irises. Besides having bear and sometimes colorful skin on their heads and necks, some New World vultures, most New World vultures are bedazzled with other fleshy features on their noggins. Ornaments like waddles, combs, and bumpy, wrinkly skin are conspicuous on most of the species. These various skin protuberances are all types of what ornithologists call coruncles. Coruncles C-A-R-U-N-C-L-E-S.

In these vultures, caruncles are probably related to sexual selection and or species recognition. We'll circle back to talk a little more about why birds in the family cathartity have naked heads when we look at what and how they eat. Now, what about the beaks, the bills of vultures and condors? They're shortish to medium and length. They're rounded off at the end, but have a hooked tip on the upper mandible. That hook helps the bird tear apart the soft flesh of dead animals. Some species, like the condors, have stronger bills and are better at tearing into thick mammal skins.

One fun feature of catharted beaks is their nostrils. If you look at the head of, let's say, a turkey vulture from the side, you can see right through the nostrils, like you're looking through a keyhole. There's no septum, no dividing wall between the two nostrils. This condition is called perforate, like the perforated paper in a notebook, right, which has holes in it. These sorts of nostrils are also sometimes referred to as pervious. What's the opposite of impervious? Pervious, of course. Not to be confused with pervy. That would mean something else entirely. Despite their superficial resemblance to eagles and hawks, New World vultures differ from those raptors in many ways.

Eagles and hawks are famous for their sharp talons and powerful grasping toes. Our vultures, however, have relatively dainty toes and short talons. This reflects their very different lifestyle and approach to feeding. New World vultures don't have to catch. and kill live prey, so they don't need those fierce talons. Looking at the plumage colors and patterns of birds in this family, you'll see that each species is mostly black, or maybe dark brown, with some white accents. The exception is the king vulture, which is mostly white, with some black accents. At least one species, the greater yellow-headed vulture, Cathartes Melambrotus,

has a greenish or purplish iridescent sheen on some of its black wing feathers. The appearances of males and females are pretty much the same in this group of birds, except that is, for the Andean condor. Males in that species have neck waddles and a comb on their head, which the females lack. So all of that covers the general size, shape, and appearance of New World vultures. What other outstanding traits do these birds share? Here's one. You know how when you're out walking around on a hot summer day,

and then you decide to cool off by peeing on your own legs? No, just me? Well, New World vultures know what I'm talking about because that's the trick they use when they need to cool down. They pee slash poop on their own legs. I say pee slash poop because liquid and solid wastes are excreted simultaneously, right? Birds don't go number one and then number two separately. It's all number zero or number X. I don't know. Anyway, these vultures use the power of evaporative cooling to their advantage. The water in their droppings evaporates off of the skin on their legs. This transfers heat away from blood vessels just under the surface there.

It's sort of the vulture's version of sweating. This unusual behavior is called urohydrosis, uro as in urine, and hydrosis as in sweat. Hydrosis, the word starts with H-I, not H-Y, is a fancy medical term for sweating. The last general trait I want to mention about these birds is their voice. Do they sing beautiful songs like meadowlarks or nightingales? No, they don't, and they can't, because birds in the family cathartity don't have a syrinx. Maybe you recall from episodes five and six of the podcast that the syrinx is the organ used by many

birds, including songbirds, to produce complex vocal sounds. Without a syrinx, new world vultures can only make simple grunting and hissing sounds. Singing is not one of their talents. So you wouldn't want a vulture to try to sing you to sleep with a lullaby. All that hissing and grunting would probably just give you nightmares. Let's consider the diversity, distribution, and habitats of New World vultures. Cathartody is the only family of birds within the order cathartiformes. Remember that order is the taxonomic rank above family. So these birds not only belong to their own family,

they're so distinct that they're set apart in their own order. The family cathartity isn't all that diverse. It contains only seven species. There's the two condors, Andean and California. California, then there's the king vulture, the black vulture, and there are three species in the genus Cathartes. Those three are the turkey, lesser yellow-headed, and greater yellow-headed vultures. As a group, the New World vultures are found across all of South and Central America, throughout the lower 48 in the United States, and into southern Canada.

The familiar turkey vulture, Cathartis Aura, is the most widespread of the seven-state. species. It soars the skies of that entire range I just described for the group, from the southern tip of South America, up into the mountains and plains of southern Canada. The black vulture isn't as widespread as the turkey vulture, but it's the most abundant species in the family. You might not be surprised to hear that the highly endangered California condor has the smallest range of any New World vulture. It's only found in its namesake state, as well as Arizona and a few other little pockets of the southwest. Catharded birds are mostly residents where they live. In other words, they aren't all that migratory as a group. However, the more

northerly populations of the turkey vulture do head south in the winter. Here in Oregon, where I live, turkey vultures are common all summer. I live on a ridge top, and I see these lovely birds soaring over my yard as they ride updrafts of wind over the ridge. And occasionally, I end up spooking a turkey vulture or two off the road as I drive home. They'll be scarfing down on some dead squirrel meat when they see my truck come around the corner. They hop lazily off the road and wait patiently for me to pass before resuming their meal. I wave at them, give them a thumbs up, and blow them some kisses. By late October or so, my local turkey vultures are gone.

They head for warmer, drier places to spend the winter like California and Mexico. New World vultures can be found in just about every single habitat across their vast range. They scavenge for carcasses in deserts, grasslands, high mountains, wetlands, and beaches. Some species, like the king vulture and greater yellow-headed vulture, live primarily in the tropical rainforests of the Amazon basin. There's no shortage of dead animals out there in all these habitats, so it makes sense that we would find vultures of one species or another, just about anywhere in North or South America.

Ornithologists have had some trouble figuring out just how to classify New World vultures. It hasn't been easy to identify where on the avian tree of life that these vultures belong. Sure, today, the family cathartity is nested within the order cathartiformis. But back in the day, New World vultures were considered. a branch within the order falconiformies, which includes the falcons, of course, but back then it also included the hawks, eagles, and old-world vultures. Then, in the early 1990s, research using data from DNA inspired some ornithologists to change the classification of the New World vultures. These scientists moved our vultures into the order sikaniaformies. What other birds are in the order

sicaniaformies, you ask? The storks. That's right, storks. Besides the genetic data from DNA, those scientists pointed to some other evidence that seemingly linked New World vultures and storks. For example, storks also cool off by going number X on their legs. They too indulge in a little Eurohydrosis from time to time. But really, vultures and storks are closely related? Seems odd, I know. But remember that there's a lot of useful information stored in an organism's DNA. Scientists can mine that information to learn things about the organism's evolutionary history and about its relationships with other species or other families, etc. Sometimes the stories we uncover using DNA are counterintuitive.

In the early 90s, new technologies were making it possible, at long last, to access all that information in DNA. It was a revolution in biology. But the technology and the methods in those early days were far from perfect. Research on the genetics of birds and every other living thing has come a long, long way in the last few decades. So guess what? New World vultures are not closely related to storks after all. Research in the last decade, using refined methods and boatloads of genetic data, has dispelled that old way of classifying these birds. It turns out that our cathartid darlings are most closely related to birds in the order

Excipitreformis. Those are the hawks, eagles, and some other raptors. So that's the current understanding, and it seems pretty solid. But who knows? The classification of our vultures might change again someday. In hindsight, we probably should have known that New World vultures and storks aren't closely related. Sure, they share a love. of defecating on their own legs, but what about babies? Storks are famous for delivering human babies. Everybody knows that, but vultures? Not once have I heard of a vulture or a condor

dropping off a baby on someone's doorstep. I mean, come on, scientists. Open your eyes and look at the data. It's not like New World vultures haven't had enough time to evolve the behavior of delivering human babies. This bird lineage appears to have been around for roughly 60 to 70 million years. But where these birds originated, in the geographic sense, is not entirely clear.

Interestingly, there are some fossils found in the old world which might belong to members of this family. So maybe our New World vultures aren't so New World after all. But it seems this is still debatable. The best fossils we have for these birds are from only the New World, from North and South America. Regardless of where this group originated, research using a molecular clock from DNA shows us that these birds started increasing in diversity about 14 million years ago.

Species diversity reached a peak between 5 million years ago and 12,000 years ago. That spans the pliocene and Pleistocene epochs. Of course, we don't know exactly why more species of New World vultures lived during that time period. But a good hypothesis is that there was simply more dead meat lying around. We talked about this at the beginning of the episode. There were huge carcasses of giant sloths, woolly mammoths, etc. In fact, there was another group of amazing scavenger birds that thrived in those days. These were the Teratorns.

They were in their own family, but that family was still within the order cathartiformis. Territorns deserve their own podcast episode, I think. so I'm just mentioning them briefly here. The most famous species in this group of extinct birds was probably Teratornus Merriamai. It was like a supersized condor with a wingspan up to 12 feet or about 3.7 meters.

Over 100 fossils of Teratornis Merriamai have been dredged up from the Labrea tarpits in California. The scavenging birds in these two related families were more diverse in the past. So what happened? Why did so many of them go extinct by 12,000 years ago? The best hypothesis I've heard is that many carrion-dependent birds went extinct when the prehistoric megafauna went extinct. By 12,000 years ago, massive extinctions among big land mammals resulted in a lot less rotting flesh strewn across the countryside.

One interesting example of a study that supports this idea was published in 2006 by researchers at the University of California in Santa Cruz. The researchers studied fossils from a variety of carrion-eating birds from the late Pleistocene. Fossils were collected at locations across North America. The birds included were some of those massive teratorns, as well as condors, vultures, and eagles. Some high-tech analyses were used in this study to look at the isotope compositions of collagen in the fossils. In their analysis, the researchers could determine where the birds fed, either primarily on the coast or primarily inland. It turned out that populations of condors and other scavengers went extinct more often

if they depended on inland mammal populations, away from the coast. The birds that survived, the ones that didn't go extinct, seemed to be those that fed on the carcasses of marine mammals on the beach. Even after the mammoths and giant sloths went extinct, there was still a steady supply of stinky dead whales and seals washing up on the shores of North America. There's one more thing I want to say about the evolution of the family cathartity. It has to do with old world vultures. The two groups of birds, old world and new, look superficially similar to our dull perceptions with their naked heads and raptor-esque body shapes. But as I mentioned

earlier, they're only distantly related. Their similar appearance is not necessarily a reflection of any recent common ancestry. Instead, it's a wonderful example of convergent evolution. We've talked about this before. Most recently, I mentioned convergent evolution when comparing penguins with their lookalikes, the ox. As carrion-eating scavengers, New World and Old World vultures have independently evolved to have some of the same. same features. The loss of feathers on the head, the ability to eat rotting meat, and all that. Those are adaptations for the scavenging lifestyle. Natural selection has favored these traits similarly in the two separate lineages. So New World vultures are their own thing. That's why

they get their own podcast episode. They're not that closely related to old world vultures, and we now know that they have no special connection to storks. How are New World vultures and condors doing in terms of their conservation status? The news is good for several of the species. Turkey, black, and lesser yellow-headed vultures appear to have populations that are stable, or even increasing. But unfortunately, greater yellow-headed vultures, king vultures, and Andean condors are declining. The latter bird, the condor, has a status of vulnerable on the IUCN Red List. The Red List has the California Condor in the critically endangered category.

The conservation saga of this species has been pretty dramatic. I'll save the full story for another episode. But briefly, the California Condor was rescued from the brink of extinction in the 1980s. That's when every last wild condor was captured and brought into California. captivity. There were only 22 left in the whole world. Captive breeding and heavy management since then have helped the species survive. 34 years and $35 million later, the California condor population has grown to about 500 birds, including those in captivity and those in the wild.

It's a conservation success story, even though the species still needs a lot of help. This condor, the largest flying bird in North America, is still one of the world's rarest birds. So its conservation story is far from over. What caused the near extinction of the California condor? What led to the dramatic decline of this bird was, well, lead, as in L-E-A-D. One of the biggest dangers to condors was, and still is, fragments of lead bullets in mammal carcasses. The birds accidentally swallow small pieces of lead, and then they end up getting

lead poisoning. Humans have also actively persecuted the two condor species, as well as other catharted vultures. The birds have been deliberately poisoned and shot. This unfortunate behavior in some people comes from a belief that condors and vultures kill livestock, like lambs, cow calves, and such. But eating live prey like that is rare among New World vultures. So their persecution seems mostly undeserved, or at least blown out of proportion. Okay, yes, black vultures can get pretty aggressive. Those buggers sometimes gang up to attack and kill young mammals, including livestock. So this means black vultures come into conflict with ranchers and other human types with

some regularity. In general, new world vultures are vulnerable to human shenanigans because their populations grow only slowly. These birds take a long time to reach sexual maturity, and they lay only one or two eggs in a given breeding season. This is especially true for the larger species. It's difficult for populations of vultures and condors to rebound when they get hammered by poisoning, shooting, or habitat loss. We come now to the diet and foraging segment of the program. This is what it's really all about with these birds, isn't it?

Their macabre diet determines so much about how they look and how they live. I guess that's actually true for many types of bird. But few other birds specialize in eating something that we humans find so repulsive, something that is just waste in our minds. Vultures capture our imaginations and maybe they appeal to our perverse adolescent curiosity about all things gross. New World vultures are like that kid at school who points to the trash can and says, someone tossed a perfectly good sandwich in there. They only ate like half of it. He then picks the sandwich out of the trash, brushes off some pencil shavings, and

chows down. And along the same lines, I imagine that when a free-range cow drops dead or there's a road-killed deer on the side of the highway, the first vulture to arrive on the scene asks the nearest human, hey buddy, are you going to eat that? Birds in the family cathartody specialize in eating dead vertebrates, mostly dead mammals, but also the occasional bird, reptile, or fish. The larger the vulture slash condor, the larger the carcass it prefers. Vultures are obligate scavengers. That means they eat dead things almost exclusively. Many other birds are facultative scavengers who eat live prey regularly besides carrion. We're talking ravens, jays, golden eagles, caracaras, gulls, and birds of that nature.

Obligate scavengers are rare among vertebrate land animals. In fact, the New World and Old World vultures are the only obligate scavengers among all living vertebrates. That's pretty crazy and pretty cool. To thrive on a diet of decaying mammal meat, there are some challenges that our vultures have had to overcome. Perhaps the biggest challenge is dealing with disease-causing bacteria. I mean, why don't humans eat rotting meat? We've learned, the hard way, I'm sure, that eating putrefying meat makes us sick or can kill us. There are all sorts of harmful bacteria in there, secreting their toxins. These are the kinds of microorganisms that cause botulism, tetanus, anthrax, and more. In other words, food poisoning. So how do our vultures

happily stuff their gullets with decaying meat without getting food poisoning? The short answer is that these birds have iron guts. Their digestive systems are incredibly resistant to bacteria that cause diseases in other animals. The primary line of defense in the guts of vultures is their highly acidic stomach. Most of the harmful bacteria are simply dissolved by stomach acid. Further down the digestive tract, the lower intestine is teeming with claustridia and fusobacteria. At least that's what one study of turkey and black vultures discovered. These particular bacteria thrive on carcasses, and they're lethal to other animals that ingest them. But it seems the New World vultures have adapted to coexist with these bacteria.

which makes me wonder if it's possible that claustridia and fusobacteria in the intestines somehow limit the threats of other bacteria that make it past the churning stomach acids. Just a guess, who knows? I should point out that dead bodies aren't all equal in the eyes of a New World vulture. I mean, it's not like they seek out or prefer carcasses in the most advanced state of a decay. Really, it's the opposite that's true. These birds prefer relatively fresh meat. Maybe a carcass that's only one to three days old, something like that. Older carcasses are much less appetizing, apparently. Besides the need to deal with toxic bacteria, a New World

vulture faces the challenge of simply finding enough food. Sure, dead animals are scattered around here and there in most landscapes, but this food resource tends to be widely dispersed. Large carcasses might be separated on average by 20 miles, 50 miles, or more. This may be one reason why large, soaring birds are the only vertebrates that evolved to be obligate scavengers. Such a bird can cover vast distances in its search for the next meal, without spending too much energy in the process. So, this brings us to foraging. A New World vulture is out there soaring high on a thermal, scouring the land for something dead to eat.

How does it actually locate a carcass? This depends on which species you're talking about. Some species use their eyesight, while others depend more on their sense of smell. The three species in the genus Cathartes, including the turkey vulture, often locate decaying bodies by smell. Most of the research on this topic has been on the turkey vulture. This bird has one of the most powerful senses of smell among all birds. In fact, the part of a turkey vulture's brain associated with smell, the olfactory bulb, is the largest of any bird.

That's in both the absolute sense and if you adjust for relative brain size. A turkey vulture can detect the scent of a carcass up to perhaps a mile away. One of the primary chemicals queued in on by the bird is ethyl mercaptin. This substance is given off by dead bodies. It smells fetid and disgusting to us humans. It's kind of like onions or cooked cabbage, but, you know, worse. We can smell ethyl mercaptin in concentrations down to one part ethelmercaptin in 2.8 billion parts of air. The turkey vulture, on the other hand, can smell this chemical at a concentration

an order of magnitude lower at only a few parts of Ethelmer Capton per trillion parts of air. Black vultures, king vultures, and the two condor species don't have this amazing sense of smell. They rely on their eyesight instead. From way up in the air,

one of these birds might spot a carcass lying on the ground. But perhaps more often, they just look for other vultures. For example, black vultures fly at higher altitudes than turkey vultures. When a black vulture sees turkey vultures congregating down below, that's the cue to swoop down and see what's cracking. King vultures and condors are larger than any of the species with a good sense of smell. These big bruisers wait for the smaller species to lead them to the buffet.

Then they muscle their way in to dominate the scene. I talked a bit about this at the beginning of episode two of the podcast, which was all about competition between bird species. But this isn't a simple case of the larger bird species acting as bullies to the smaller species. There's actually more interdependence between the species than we might think at first. Earlier I mentioned that the larger birds, like the condors, have stronger bills. So those species are the only ones capable of tearing into the thick hides of recently deceased mammals. Turkey vultures and the other smaller species often depend on the larger birds to open up a carcass.

This results in a sort of mutualism, a relationship between the species where each of them benefits from their interaction. It's as if a turkey vulture says, Hey, you, tough guy. Yeah, I'm talking to you, Mr. Andy and Condor. I have a proposition for you. How about you and me team up?

I'll use my super sniffer to find us a dead donkey. Then, if you use that beefy bill of yours to tear the donkey open, be generous and let you get first dibs on the meat inside. Sound like a deal? Not that any of these birds are necessarily making these decisions consciously. Each is just looking out for its own self-interest, by following its instincts. In any case, what happens between the species isn't purely competition or purely cooperation. It's something in between. In regions where no large vulture or condor species exists, like Eastern

North America, the smaller vultures have to depend more on the help of scavenging mammals like coyotes. Or they get creative and try to get through the thick carcass skin on their own. Turkey and black vultures will often breach a carcass through a weak point. You know, a weak point, like an eye socket, the navel, or the anus. Seriously, the anus. I mean, a vulture's got to do what a vulture's got to do. Now, picture several species of vowsons. vultures gathered around a carcass. The species don't necessarily focus on the same parts of the carcass or eat in the same way. Vultures of all kinds, both New World and old, have been classified by scientists into three feeding groups. Gulpers, rippers, and scrappers. Gulpers stick their

heads deep into the soft tissues of a carcass and swallow big chunks. The two condor species and the black vulture are all gulpers. Rippers feed on body parts closer to the surface. They prefer tougher pieces like skin and tendons. The king vulture is in the ripper category. The three remaining vulture species are scrappers. Scrappers peck around for small loose pieces of meat, i.e. scraps, on the carcass, or on the ground nearby.

So that's gulpers, rippers, and scrappers. I'm thinking we've got some new product names for candy here. Hey, kids, do you like Snickers and Whoppers? Well, you're going to love gopers, rippers, and scrappers. The secret ingredient is Ethel McCaptain. Having a naked head is helpful to any vulture that plunges its face into rotting corpses, whether gulping, ripping, or whatever. birds in general like to keep their feathers clean and in good condition vultures would have a hard time doing that for any feathers on their heads these would get all sticky and caked with dried blood and guts not very sanitary right we can infer that a naked head is probably a useful adaptation in scavenging birds because we find this trait in both new world and old world vultures remember that this similarity would be a

have evolved independently in the two groups. Another hypothesis is that featherless heads help keep these birds cool in hot weather. A sluggish vulture or condor with a belly full of dead donkey meat or whatever is going to have a little trouble taking off. The weight and wing shapes of these birds don't allow them to burst into the air like grouse, ducks, or songbirds. So it seems new world vultures are vulnerable to predators when they're on the ground near a carcass. And indeed, they tend to be skittish and wary of predators.

But interestingly, there don't seem to be many documented cases of predation on our vultures. Golden Eagles, canines, wild cats, and large snakes probably nab the occasional vulture if the opportunity happens to arise. And there are a few confirmed examples of this happening. Predators must be a serious concern, at least to the turkey vulture. This species has a revolting adaptation as a defense against predators. When a turkey vulture feels threatened by a fox or some other critter, it will sometimes barf up a wad of half-digested carcass meat in the general direction of the offender. This disgusting slurry not only smells foul, it's also highly acidic.

so it might burn the eyes or mouth of an attacking predator. I'd say that's a pretty strong deterrent. I know that I'd stop whatever I was doing if a vulture puked on me. You'll see a bunch of articles online saying that turkey vultures have, quote-unquote, projectile vomit, and that they can shoot their barf up to 10 feet. Sounds like a pretty awesome superpower, but I'm not sure I buy it, since I couldn't find any reputable sources that back up this claim. Vomit, yes, projectile vomit, maybe not.

In any case, this brings us back to the Greek word catharos. Besides being related to something that is pure or cleansing, this is also the root of the word cathartic. In medical terms, something cathartic is a purgative. It makes you throw up. So the genus name cathartis, at least for the turkey. vulture carries something of a double meaning, wouldn't you say? There's still a lot that ornithologists don't know about how New World vultures breed.

The species we know the most about are the California condor and turkey vulture, naturally. But all species in this family are monogamous and the parents share in the duties of raising their chicks. They don't construct a nest. They just lay their eggs on a bare surface. This is often in a small cave or crevice on a cliff. But some species will place their eggs in a variety of places, including hollowed out trees, old raptor nests, or even the ruins of Mayan temples, which is pretty rad.

As I mentioned earlier, one or two eggs per clutch is typical. Each of the two Condor species invariably has only one. one egg. Mom and dad forage for carcasses and return to the nest to regurgitate meat for their chicks. The larger species have fewer chicks, and they invest more time into raising their offspring. For example, an Andean Condor chick takes about six months to reach the fledgling stage. Even after that, its parents will keep feeding and caring for it for another four months or so. The entire process for Andean Condors, from egg to the chick becoming independent can last over a year. This is why these birds probably breed only every other year.

Young New World vultures take a long time to reach sexual maturity. They might be five to ten years old before they ever have their first chick. But with luck, they will have many breeding opportunities over their lifetimes. New World vultures are long-lived birds. The lifespan records we have for turkey and black vultures are 17 and 25 years, respectively. And scientists estimate that condors can live 50 years or more. I've had a few close encounters with New World vultures, mostly with captive individuals that had been rescued and then trained to be educational birds. They seem to be gentle-hearted creatures.

I found them charming, and I could tell that their caretakers really loved them. It turns out catharted vultures don't really fit into the cartoon stereotype of being wicked, morbid creatures that are just waiting for all of us to die. In any case, it's probably not fair to project human emotions or motives onto these birds, whether good or bad. But I have to say that in my limited experience, these vultures seem pretty gentle and lovable. But even if they were jerks with bad attitudes, I'd still have to sing their praises. Or more appropriately, I would maybe hiss and grunt their praises.

Because New World vultures play such an important role in our ecosystems. They are, arguably, just as essential as top predators or herbivores, or you name it. These birds keep the circle of life grinding along. They help to convert dead animals back into soil. and their services probably minimize the spread of bacterial diseases. Vultures keep our environments relatively clean and sanitary. So it's odd that human societies don't value these birds more than we do. But I guess that's kind of how we operate, right?

We sometimes shun or look down on other humans whose occupations have to do with waste, death, or disease. In extreme and unfortunate cases, people with these jobs become quote-unquote untouchables in our societies. Vultures, too, get unfairly treated like this sometimes. So let's try to give these birds more appreciation, more respect and love. I know you're with me on this, but we can also spread the word to folks who may still have misunderstandings about New World vultures.

And hey, we might also want to tell everybody that when the inevitable zombie apocalypse happens, vultures and condors might be our new best friends, or even our saviors. Imagine a scenario where you and a few other survivors are surrounded by a horde of terrifying zombies. You're fighting them back in a desperate struggle to escape. But those rotting zombies would be giving off fetid clouds of Ethelmer Captain, right? And you know who can't resist that smell? So just as the zombies are closing in with their grasping hands and gnashing teeth, someone in your group yells the vultures are coming the vultures are coming and down from the sky

comes a huge flock of turkey vultures black vultures king vultures and even some mighty condors the birds are worked into a frenzy by all that ambulatory dead meat they descend on the zombies like a black storm flapping and pecking furiously the zombies are assaulted by all those gulpers rippers You and your friends take this Deus ex machina opportunity to run away, to escape and live another day. Hooray for New World Vultures! And there you go.

The family cathartity. I really hope you enjoyed this episode. I certainly had fun making it for you. There are so many fascinating things about New World Vultures. I'm sure I could have made this episode twice as long and still have more to say about these awesome birds. You know who else is awesome?

The wonderful people who support the science of birds on Patreon. The monthly contributions of my patrons help me buy enough coffee and granola bars to keep me going as I write, record, and edit podcast episodes. But seriously, there are real expenses for running this program, and I'm also trying to make it a sustainable source of income. So thank you very much to those of you

who are giving your support. My newest patrons are Rachel Bloom and Walter Vines. I really appreciate the help Rachel and Walter, thank you. If you are thinking about becoming a patron, you can check out my Patreon page over at patreon.com forward slash science of birds. And if you have something you'd like to share with me, please go ahead and shoot me an email.

Maybe you have a comment about the podcast or you want to tell me how when you were a baby, you were delivered to your parents by a vulture. In any case, my address is Ivan at Science of Birds.com. I'm your host, Ivan Philipson. Thanks for being here, and I'll catch you in the next episode. Cheers.