The Science of Birds - Nightjars, Nighthawks, and Other Goatsuckers

Episode Date: May 12, 2025

In this episode, Ivan Phillipsen takes listeners on an immersive journey into the strange and secretive world of birds in the family Caprimulgidae. These cryptically colored, nocturnal birds include nightjars, nighthawks, poorwills, and whip-poor-wills. Ivan reveals the fascinating biology of this group—everything from their frog-like gapes to their odd names and eerie calls.Listeners will learn about the distinctive physical traits and behaviors that define caprimulgids, including their specialized eyes for low-light vision, aerial insect-hunting strategies, and mating displays involving wing claps and booming dives. Ivan also explores their global distribution, evolutionary history, and conservation status, while highlighting standout species like the Lyre-tailed Nightjar, the Common Poorwill, and the elusive—and possibly nonexistent—Nechisar Nightjar.This deep dive into Caprimulgidae is packed with scientific insights and fun facts. Whether it’s unpacking myths of goat-milking birds or listening to spooky vocalizations from around the world, the episode celebrates the mystique and diversity of these birds that thrive in the twilight.~~ Leave me a review using Podchaser ~~Link to this episode on the Science of Birds website Support the show

Have you ever found yourself staring at a pile of dead brown leaves for several long minutes, hoping that the pile of leaves will magically resolve itself into a living creature? Well, I guess that's a silly question, though, right? Because of course you have. Well, I've done this in various tropical places, walking around, scrutinizing the leaf litter on the forest floor, looking for things like insects, frogs, and chameleons. because some species have evolved to be camouflaged to appear just like dead leaves. Biologists would say these animals are cryptically colored. One of my favorite memories with a cryptic critter like this is from Madagascar a couple years ago.

I was there leading a birding tour, and we were in Andesibay Montadilla National Park. My group and I were walking a trail through the rainforest when one of our local Malagasy guides informed us that there's a special bird nearby. The specific location was at the top of a steep, muddy slope, so we went up in small groups to take a look. I clambered up there, and then there I was, holding onto a small tree so I didn't slide down the slope. The guide was pointing at a patch of brown leaves. He said, There, there, look. But at first I saw nothing but a bunch of decaying leaves. I couldn't see any birds. But I kept looking, and then, like magic, ta-da, there it was, a beautiful collared night jar, Gactornis and Eretus.

It was sitting among the leaves, and its plumage was amazingly well camouflaged. It had a big head, a tiny bill, and large eyes half covered by squinting eyelids. But it turned out that, wait, there wasn't just one bird, there were two collared night jars sitting side by side. It was a mated pair snuggled right up against each other. It was adorable and beautiful. The birds let us get relatively close because they assumed their camouflage would keep them safe. They were like, nothing to see here, just a dirty old pile of leaves. Move along. Seeing any species of night jar at its daytime roost is exciting. Seeing these collared night jars was especially thrilling because this is an endemic species.

It's found only in Madagascar. And it's the only species belonging to the genus Gactornis, G-A-C-T-O-R-N-I-S. I got a very pleasant surprise when I looked up the origin of this name. I recognized the second part, Ornus, as meaning bird in Greek, but Gacted was unfamiliar to me. It turns out that the genus Gactornis is quite new. It was assigned to the collared night jar in 2010. Before this, the species was in the genus Capromulgus.

Anyway, GACT, comes from the four letters used to represent the nucleotide molecules that make up DNA, guanine, adenine, cytosine, and thymine, G-A-C-T. Ornithologists were able to discover the evolutionary distinctiveness of the collared nightjar using genetic evidence from DNA, rather than any physical traits. So, coming up with the name Gactornis was a clever way to honor that origin story. Pretty cool. And you know what else is pretty cool? All the other night jars, nighthawks, and poor wills in the world.

Together they make up the avian family, Capramulgadi. 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 116. It's all about birds in the family Capramulgadi. These are the nearly 100 species of night jars, night hawks, poor wills, whippoorwills, and parakees. I might just use the name Night Jars today as a shorthand way to refer to the entire group.

And we can also call them Capramulgids. In any case, this is a specialized lineage of nocturnal birds. They give off an owl-like vibe with their preference for nighttime shenanigans and their camo-themed plumage. In fact, some English names for these birds from a few hundred years ago include fern owls, churn owls, and wheel owls. But birds in the family Capramalgadi are not closely related to owls. The similarities are only superficial. And there are a few other groups of nocturnal cryptic birds that you might confuse with night jars. But we'll get into all of that a

little later. Given their cryptic nocturnal ways, night jars easily elude many of us birders. These aren't birds you necessarily expect to see on any given birding outing. Despite their elusiveness, or maybe because of it, people seem to really like night jars. And it seems the members of my Patreon community are especially fond of these birds. One of the perks of being a member and supporting the show is getting to vote in polls. In the latest poll, I had my patrons vote on the bird family for this episode. The options were night jars or kiwis. So, two groups of nocturnal birds. Everybody loves Kiwis, right? So I thought maybe those birds would annihilate night jars in my pole. But nope, quite the opposite. Night jars, Capramulgids,

won 79% to 21%. Not even close. Kiwis will get their podcast episode for sure, but today we are obliged to shine our spotlight on the family Capramulgadi. There's another collective name frequently used for these birds, goat suckers. I'm serious, goat suckers. Now, if that's news to you, you're welcome. You've unlocked a new silly bird fact. This weird name originated thousands of years ago in the time of the ancient Greeks. There was a long-standing myth that night jars would swoop in under cover of darkness to drink the milk of female goats. This alleged behavior, which I must stress is not true, would cause the goats to cease producing milk or even go blind. Not surprisingly, this didn't give night jars a good

reputation. The birds were vilified, blamed for any misfortune that happened to domestic goats. But I guess goat suckers had it better than some other birds with imaginary behaviors. Even more despised and persecuted by people in ancient times were the pig pinchers, cow ticklers, and horse harassers. But that's all ancient history, thankfully, and also not. true. Except for the goat sucker part, that is 100% true. So if they don't suck goat milk, what do night jars, capromulgids actually eat? They are specialists in eating flying nocturnal insects, like moths and whatnot. We'll go into more detail on the diets of capromulgids a little later. It's fair to say these birds are nocturnal. However, many of the

species are most active in the hours just after sunset and and just before sunrise. So, really, they're more crepuscular. And that's a great scientific word. It's got some meat to it, right? You can kind of chew on it. Crepuscular. A crepuscular.

I assume that's how you say it in Italian. Crepuscular birds and other animals are active in the dim light of evening and or early morning. So night jars, night hawks and such are active in low light, sometimes very low light, but not in total darkness. And when the moon is out, these birds might be active for most of the night, because moonlight has a strong influence on their activity.

Unlike other nocturnal critters, like many owls and bats that zero in on their prey using sound, night jars have to use their eyes to hunt. That's why they need at least a little bit of light. Okay, let's jump in and get to know the birds in this family. We'll start with their key traits, their shape, size, plumage, and all of that good stuff. If you're trying to conjure the image of a typical bird in the family Capramulgadi, I'd say start with an oversized sort of flat head, with a couple of large, dark eyes bulging out on the sides. The eyes of night jars reflect light and seem to glow at night when you catch them with car headlights or a flashlight, or in other words a torch for my British friends. These birds seem to be a bit front-heavy, with a body that tapers towards the tail.

The relatively long wings and tail allow a nightjar to be highly agile in flight. Some species, like the eastern whippoorwill, have shorter, more rounded wings. tail length is also variable. Some species have shorter tails, while several species have fantastically long tails. These include the swallow-tailed nightjar and lyre-tailed nightjar. Both live in the Andes Mountains of South America, and they're the only members of the genus, Europe Salus. All birds in this family have short legs. The bill has an unusual shape.

It's very short, almost dainty, you might say. But while the bill may be small, the mouth overall is freaking massive. These birds have a very wide gape. Like if you're trying to spoon feed a fussy nightjar and you say, Here comes the airplane, open wide, yum, yum, open wide. You might be terrified by what happens next when the bird complies with your request. Suddenly, you're faced with a cavernous pink maw that seems capable of swallowing your entire head. Also, it sort of looks like Kermit the Frog screaming.

The broad mouths of Capramulgids are indeed frog-like. You might have even heard of a group of birds called frog mouths. But frog mouths are not in the family Capromulgadi. They're in a family of their own, Podargadie, which is somewhat closely related to Capromulgadi. An interesting feature of the bill and mouth on a night jar is the presence of rictal bristles. That's rictal R-I-S-C. C-T-A-L, not rectal. Remember that bristles are specialized feathers that look more like hairs.

They lack the barbs found on your typical contour or flight feather. So there are these stiff rictal bristle feathers jutting out from around the rim of a night jar's mouth. Ornithologists aren't exactly sure what their function is. In nocturnal birds like these, it could be that they have a sensory function. Maybe they work like whiskers on a cat. Other possible functions of rictal bristles include eye protection from the flailing, spiky bits of insects, or working like a funnel to direct aerial prey into the pink void that is the bird's mouth.

In the latter case, the rictal bristles would work sort of like the pocket at the end of a lacrosse stick, or like a catcher's mitt in baseball. And in case you're wondering, the word rictal comes from the Latin root rictus. which means an open mouth. As birds go, capromulgids are medium-sized. Many of them are roughly the size of an American Robin or a Eurasian blackbird. The largest member of the family is the great-eared nightjar, Lincornis Macrodis.

It approaches the size of an American crow, with a length of about 16 inches or 40 centimeters. This species lives in Southeast Asia, the Philippines, parts of Indonesia, and parts of India. I remember being really excited to see and hear great-eared night jars as they flew over a river in Vietnam in the hour before sunrise. Here's an example of the call that this bird gives in flight.

Great-eared night jars are really cool-looking and, I got to admit, cute-looking birds. The ears are tufts of feathers on either side of the head, sort of like the ears or horns of some owls. The Great Eared Nightjar kind of looks like the character Toothless, The Dragon, in the animated movie How to Train Your Dragon. As for the smallest capromulgid, there are several species that could compete for that title. These include the least night jar and the pygmy night jar, which are only about six to eight inches long, or 15 to 20 centimeters. Birds in this family are cryptic, right? Like those collared night jars in Madagascar.

So when it comes to their feathers, their plumage, these come in various earth tones that blend in with dead leaves, bark, and branches. We're talking gray, tan, beige, cream, tawny, rufus, umber, sepia, brown, off-brown, hyper-brown, hash-brown, and so on. Most species also have some black-and-white markings as well. Camouflage results from not just the colors, but from the intricate patterns of color on the feathers. When they sit still, when they're roosting on the ground or on a tree branch, these birds are almost invisible. Some species have lighter colored plumage that works well in dry habitats.

For example, there's Sykes Night Jar, Capromulgus Mara Tensis. Its range is centered in Pakistan, and it lives in habitats like semi-desert, scrubland, grass. travel plains and stony wastelands. Sykes Nightjar has sandy gray upper parts with light blackish-brown spots. Its sandy-gray wings are streaked with blackish-brown and they have some buff spots. This thing has evolved to be well camouflaged in arid environments. And Sykes Nightjar is really good at psyching people out. I can picture a birder scrambling around in a stony wasteland searching for the elusive bird

when suddenly it seems to appear out of nowhere and takes off from the ground. As it flies away, it yells over its shoulder, Sike! Oh, how I wish that's how this bird got its name. But no. The true story is way less interesting. I guess Sikes, S-Y-K-E-S, refers to Colonel William Henry Sykes, an English ornithologist and army officer back in the 1800s.

Some capromulgid species show sexual dichromatism, or dimorphism in their feathers. Males and females can differ in the white markings on their throats, wings or tail. For example, common nighthawks have white throats and a white band in the tail that are not present in the female.

And the conspicuous white wing patches in this species are larger and cleaner looking in the male. There are some extreme examples of sexual dimorphism in this family. In several species, the male has extremely large ornamental feathers. I mentioned the swallow-tailed and lyre-tailed night jars earlier.

There's also the long-trained and scissor-tailed night jars, which are also found in South America. In Africa, there are a couple more species that show extreme dimorphism. The pennant-winged nightjar and the standard-winged nightjar. On each of his wings, the male pennant-winged night jar has a super-long second-inermost primary feather. In flight, these feathers trail out behind. hind like a pennant, like a tapering flag or streamers. They're longer than the body of the bird itself.

The male standard-winged nightjar is even crazier, in my opinion. His unusual feathers are, once again, the second innermost primaries on the wing. They have naked shafts, for the most part, but then at the tip, the feathers expand so that the vein has a broad, leaf-like shape, sort of like a different kind of flag, a standard. In both, species, males make display flights at dusk to show off their crazy ornamental feathers to spectating females. It's likely that the feathers are a signal of a male's genetic fitness. If you want to learn more about this sort of thing, be sure to check out episode 27 of the podcast, which was all about sexual selection in birds. Let's move on to talk about the sounds that night jars make. Many

species have strange haunting calls, whirring, churing, booming, or painting. Some of the common names of these birds are onomatopoeic. And what I mean by onomatopoeic is a bird name that mimics the sound of the bird's own vocalization. Its name sounds like its call. The eastern Whippoorwill is a great example. Someone heard the following call back in the day and they decided it sounds like Whippoorwill. Similarly, the common poor will is supposedly saying poor will when it calls. See if you agree with that assessment.

Here's a common poor will in Washington state. Next up, we have the Puerto Rican nightjar, an endemic species on the island of Puerto Rico in the Caribbean. Moving over to Africa, here's the sound of a male Rufus-cheeked night jar in South Africa. He starts up with a few introductory awoop sounds, then he makes a long, continuous, cheering sound. We already heard the great-eared night jar earlier, but just for fun, here it is again. This one was recorded in Thailand.

Birds in this family tend to fly quietly, and that might be the result of having soft feather. sort of like owls. But sometimes these birds deliberately fly noisy. During aerial displays, some species use their feathers to make mechanical, non-vocal sounds. And I believe it's only the males that do this. Here's an example.

The following recording is of a European nightjar in Italy. What you hear is a short call, followed by snapping sounds that are actually wing claps. This is a territorial display made by a male. The common night hawk, a familiar bird in the Americas, makes a booming sound with its feathers. This happens when air rushes through the primary feathers after a sudden downward flexing of the wings during a display dive.

We're going to listen to a recording of a common nighthawk doing some of these dives. You'll hear the short nasal peat calls, then there's this relatively loud, booming sound that happens at the bottom of the dive. People call it booming, but I don't know, it doesn't sound quite like a boom to me. But decide for yourself what you think it sounds like. Okay, here we go. Yeah, see, I don't know. The boom sounds to me more like a buzzy twang,

like someone snapped a rubber band or a bowstring. A number of other nightjar species make mechanical sounds with their feathers. For example, the male ladder-tailed nightjar in South America makes loud, strident mechanical bursts of sound during his dramatic diving twists in flight. Now it's time to look at the diversity and distribution of Capramulgids, as well as their migration patterns and habitats. But first, I want to touch on the origin of the family name Capramulgadi.

Can you guess where it can you guess where it can? came from? If your zodiac sign is Capricorn, the astrological symbol is a goat, right? It's a very weird goat with a fish tail for some silly reason. And if we call someone capricious, we mean that they're impulsive or unpredictable, sort of like a frisky goat. So the etymology, the word origin of capromulgidae, comes from Latin capra, meaning goat, and mulgare, which means tumult. So that brings us right back to the whole goat-sucker myth. One other name you might be wondering about is night jar. What's the deal with the jar part?

Well, according to the bird name book by Susan Myers, Jarre refers to the sound made by the Eurasian night jar. People who named this bird long ago thought the sound it made at night was jarring. It was discordant, clashing, maybe a bit spooky. And this same species was, at times, known by other names. Names like Night Raven, which means Knight Raven, and Nightchur. You remember the trilling, cheering call of the Rufus-cheeked Nightjar I played for you earlier.

Well, the Eurasian Night Jar makes a similar cheering sound. Let's listen to it. Does this sound jarring or spooky to you? If you know a little something about the diversity of birds around the world, you've probably heard of, if not seen, some nocturnal birds that are similar to night jars, but are not in the family Capramulgadi. These include the potus of Central and South America and the frog mouths of Australasia and Asia. Potus and frog mouths are also large-headed, cryptically colored birds.

Until just a few years ago, ornithologists included them along with night jars, Owlet night jars, the oil bird, tree swifts, swifts, and hummingbirds in the avian taxonomic order, Capramulgaformis. Now, however, these different families have been divided into a number of different orders. The order Capramulgaformis, as we define it today, has been paired down to include only the family Capramulgadi. So even though potus, frog mouths, and the oil bird look sort of like night jars, these groups belong to their own families or even their own orders.

But those orders are still clustered together on one big lineage of the avian tree of life. So they are somewhat closely related compared to many other birds. Let's return to looking at just the family Capramulgadi. Some scientific papers and other info sources point out that this family can be divided into two distinct lineages, two sub-families. There's Cordelanee, the Nighthawk sub-family, and Capromulgini, the typical Nightjar sub-family. The ornithologists who defined these two groups relied on physical characteristics like wing-shape, pallet-structural. and rictal bristles. One behavioral difference that seemed to be consistent between the sub-families cordalini and capromulgony is that nighthawks capture insects in continuous flight, whereas night jars

typically hunt flying insects by launching from a perch. However, it seems the current thinking about the traditional sub-families is that they are not supported as valid taxonomic groups by molecular evidence from DNA. So I guess we have to toss these sub-families into the trash can of outdated scientific ideas, sort of like a dirty old pile of brown leaves. In terms of diversity, there are 98 species in the family Capromulgody, and these are grouped into 28 genera. The genera showing the most diversity are Capromulgus with 39 species and antistomas with 12.

The number one best name among all 98 species is, I have decided, the Diabolical Nightjar, Eurostopatous Diabolicus. And I'm not joking, this is a real bird. It lives on the island of Sulawesi in the Indonesian archipelago. I got curious about how the diabolical night jar got its name, so I looked into it. This is the name used by the Clemens checklist of birds, but it turns out the International Ornithological Congress World Bird List, the IOC list, labels this species with an even better common name, the satanic nightjar. This species, scientific, and common names are inspired by its calls. One of its vocalizations made while flying is sometimes described as a rapid plip-plop, almost like dripping water, or, according to local people in Sulawesi, the sound of

a bird pulling out a person's eye. For real. Ah, yes, the familiar sound of an eyeball being plucked out of its socket. It's like music to the ears of cannibals, vultures, and devil-worshippers everywhere. Good stuff. Now, I said there are 98 species in the family Capromulgadi. But that might soon drop to 97, because one of those species, the Netschisar Nightjar, might not actually exist. This bird has presented ornithologists with a mystery for over 30 years. In 1990, a birding expedition in Ethiopia's Nechisar National Park found a single wing from a road-killed bird. The wing's length and a distinctive white patch on its outer feathers

led to the identification of a new species, the Nechisar Nightjar, capromulgus Solala, in 1995. Due to there being only one specimen and the absence of any sightings, this species is thought to be rare and limited in its distribution. And when I was looking through the images of capromulgid species on the Birds of the World website, I saw that the illustration of the Netschisar Nightjar is just a single wing, because that's all we have to go on for this enigmatic bird. There's actually an entire book about it, titled Search for the Rarest Bird in the World,

published in 2015 and written by Vernon R. L. Head. Well, it now looks like the rarest bird in the world isn't actually a bird after all, not a unique bird species, that is. Because some very recent research using DNA provides strong evidence that the Netschisar nightjar was actually a hybrid individual. By analyzing the genetics and physical traits of the wing and comparing them to other African nightjar species, the researchers who published this study found that the Netshasaar Nightjjar likely resulted from the breeding of a standard-winged night jar and possibly a freckled night jar.

Mystery solved, case closed, so long Natchasar nightjar. It was fun while it lasted. You too must be tossed into the trash can of ornithological ideas that proved to be untrue. All right, switching gears. Let's look at the geographic distribution of the family Capromulgadi. This is a cosmopolitan group. jars are found across most of the planet, but they're particularly diverse in tropical environments. And I guess that sort of makes sense, since these birds eat bugs that fly around at night. The tropics are swarming with lots of night jar food. Conversely, large parts of northern North America and Eurasia are lacking these birds in the boreal and arctic latitudes. And you know where else you won't find a single bird in this family? I'll give you one guess.

And no, the answer isn't, your mom's house, as hilarious as that might be. No, the correct answer is, of course, Antarctica. The continent we all love to hate, the virtually birdless void that should be avoided at all costs, unless that is you like penguins and want to die slowly by freezing. Every other continent, I'm happy to report, hosts a delightful selection of capromulgid species. But I guess there's one more place that these birds are conspicuously absent, and that's New Zealand, which is a little bit surprising to me. We saw that with the Osprey, too, right, in a recent episode. Anyway, looking at the continents, the species most commonly observed in North America are the common nighthawk, common parakei, lesser nighthawk, eastern whippoorwill, common poor will, and Chuck Will's widow.

And yes, that's a real bird name, Chuck Will's widow. And since I mentioned the common poor will, Phalynoptilus Natalii, I want to briefly mention a superpower that this bird has. I'll save a longer discussion for a future podcast episode on just the common poorwill. Anyway, the superpower is being able to hibernate. When you think of hibernation, you probably picture mammals, squirrels or bears curled up in a winter den, or humans in cryogenic sleep aboard an interstellar spaceship. But some, Some birds can lower their heart and breathing rates and their body temperature as a way to conserve energy when it's cold.

Some hummingbirds do this on a nightly basis. This physiological state is called torpor. Well, the common poor will in the southwest of North America will sometimes hunker down in the winter, staying dormant, staying in torpor, for days at a time. And that we know of, this is the only bird that comes close to hibernating in the way many mammals do. The Hopi people, whose ancestral lands in the southwest are swarming with common poor wills, apparently recognized the bird's unique ability long ago. Their name for the poor will translates to the sleeping one. Anyway, cool, but we were talking about geography. I listed

the handful of most common capromulgids in North America. In South America, the top two species are the common parake and the scissor-tailed nightjar. In Europe, the most commonly observed species are the Eurasian nightjar and the red-necked nightjar. The fiery-necked and square-tailed night jars top the list in Africa, while in Asia it's the savanna and large-tailed night jars. And finally, Australia's most common species are the white-throated night jar and spotted nightjar. A number of species undertake migrations, although the secretive nature of these birds can make it challenging to fully understand their migratory patterns. Species that live in northern regions, such as the Eurasian nightjar and the common nighthawk, migrate southward when winter rules around.

The Eurasian nightjar is highly migratory, with different populations in the species having specific migration roots and wintering grounds, primarily in eastern and southeastern Africa. For example, data from geolocators has shown that Eurasian night jars from southern England winter in the south of the Democratic Republic of the Congo. Over in the New World, the common nighthawks migration pattern needs more research, but we do know that there are some impressively long distances between breeding areas in North America and wintering areas in South America. In fact, this bird migrates farther than almost all other North American species.

1,500 to 4,200 miles, or 2,500 to 6,800 kilometers. Other species also show migratory behavior, though often over shorter distances. Some species have populations that are largely sedentary, while others are locally or partially migratory, such as the common parake, savanna nightjar, and white-throated nightjar. So what kind of habitats do all these birds live in? In general, they prefer open to semi-open habitats, like grasslands, scrublands, savannas, forest edges, and clearings, often with sandy or bare ground, which is great for nesting.

They're also found in dry woodlands, deserts, and tropical forests, depending, of course, on the species. And again, because they forage for insects in flight, they prefer areas with lots of aerial insect activity and open space for maneuverability. At last, we come to the section where we answer the burning question, Where and when did Night Jars first evolve? This family is one branch of a larger lineage called Streisorres. S-T-R-I-S-O-R-E-S. Today, this lineage includes the individual orders and families of all those night birds I mentioned earlier. Potus, frog mouths, the oil bird, and Swiss and hummingbirds

are also members of this Streisori's lineage. The common ancestor of all these birds seems to have lived during the Paleocene epic in the first 10 million years after the non-avian dinosaurs were wiped out. So that's between 65 and 55 million years ago. The earliest fossil that scientists can link to the family Capramulgadi dates to the Eocene epic, about 40 million years ago, and that fossil was found in France. Other research points to the geographic origin of this family as the region surrounding the Indian Ocean. This idea is based on the current distributions of the three earliest branching lineages within Capramulgadi. These branches are the genera Eurostopidas, found in Australia and part of Indonesia, lingornis found in South Asia, and good old Gactornis, the collared nightjar

I talked about at the beginning of the episode. These three genera are the most ancient lineages within Capromulgody. Researchers have hypothesized that some ancestral night jars spread out from the Indian Ocean. They colonized the new world and then diversified there. Millions of years later, some of them made their way back to the old world and went through another subsequent radiation of species diversity. So birds we would probably recognize as members of the family Capramulgadi have been around for tens of millions of years. And now they find themselves living in the present with us.

How are they doing in the face of all the stuff that humans are doing to the planet? Well, according to the IUCN Red List, there are four sources. species in the near-threatened category, six in the vulnerable category, which is worse, and worst of all, there are two species in the critically endangered category. But those last two species might be extinct already. The new Caledonian nightjar is known from only one specimen that was collected in the 1930s, and the Jamaican Parake is represented by just a few specimens, and it basically hasn't been seen since 1860. So, even though the new Caledonian Nightjar and Jamaican Parake aren't officially extinct, it seems very likely that they are. If so,

that would take the total number of species in Capramulgadi down to 95. The primary conservation threats to night jars include habitat loss and degradation, predation, especially on their ground nests, direct mortality from human activities like being hit by cars, disturbance at breeding sites, and reduced insect prey because of our enthusiastic use of pesticides. Now we get into what and how these birds eat. Contrary to what the ancient Greeks thought, goat milk is not on the menu. And you know, just as an aside,

I want to express my concern for the welfare of goats. The poor things end up in all these imaginary situations where nocturnal creatures are trying to drain their body fluids. On the one hand, there are night jars swooping in to chug goat milk. And then there's the chupacabra, a cryptozoological beast whose name also translates as goat sucker. But it's not after milk. No, this diabolical hellspon drinks the blood of goats.

But, thankfully, all of that is pure myth. Silly folklore, right? So, instead of calling Nightjars goat suckers, we should consider rebranding them as something like moth munchers or beetle biters or, I don't know, something. These guys eat all sorts of flying insects, beetles, moths, bees, wasps, flies, grasshoppers, and so on. Most of them are opportunistic feeders,

consuming whatever flying insects happen to be the most readily available at the time. When it comes to their foraging method, we would say these birds are aerial insectivores. Other birds in that category, birds that forage this way, are swallows and swifts. Remember that the beak of a night jar is small. It looks like just a little hook at the front of the face, a nubbin, if you will. But when the bird is hunting, that beak opens wide to reveal an effective insect-catching trap. It's sort of like a net that a butterfly collector would use, sweeping it through the air to catch flying insects. And again, those rictal bristles sticking out

around the rim of the open mouth might work to increase the effective surface area of the mouth. As I mentioned earlier, night jars use their eyes to locate prey. But because they hunt in twilight, their eyes need to be really good at making the most of the very dim light. So, let's Let's consider the anatomy of a typical nightjar's eyes. First, the eyes are large, and that helps to gather as much light as possible. On the inside of the back of the eye, the retinas have a greater concentration of rod cells and a reduced number of cone cells compared with birds that are active during the day. This higher proportion of rods enhances a night jar's night vision,

but it limits the ability to distinguish colors. And remember that if you shine your flashers, light directly into the eyes of a night jar. First of all, rude, but also you'll notice that the bird's eyes will glow with reflected light. Well, that phenomenon, eye shine, is common in nocturnal animals. Their retinas have a specialized feature called a tapidum lucidum. This adaptation has evolved independently in various animal groups. The tapidum lucidum is a retroreflector. This layer of the eye reflects light that has passed through the retina back into the photoreceptor cells of the retina, giving those cells a second chance to absorb the light. And this enhances night vision.

Moth munchers have a tepidum lucidum too. It's a layer of dispersed microscopic spheres attached to pigment cells. And the spheres are made of lipids. Remember that lipid molecules are basically oils or fats, right? So all of this is sort of like what's going on with the glowing eyes of your cat or dog. But mammals and birds evolved the tepidum lucidum independently. So the anatomy of the retina is different at the cellular and molecular level. The function, however, is the same. Better night vision. So capromulgids are aerial insectivores, capturing flying insects while in flight. Some of them, like nighthawks, fly continuously as they hunt. But many other species use a method called sallying. In this method, the bird sits motionless on a low branch, log, or the

ground, relying on its excellent camouflage. When it sees an insect, the bird darts out, it sallies forth to snatch its prey in mid-air. The bird then returns to the same or a nearby perch to wait for the next insect to come along. Salying is energy-efficient compared to continuous flight and is especially effective for birds that hunt in open habitats, like clearings, forest edges, and savannas. Foraging heights vary, with some species hunting high over forest canopies or open country, while others fly low over the ground or water surfaces. Although some species forage solitarily, others may hunt in pairs, family groups, or loose flocks. Nightjars often drink by dipping to the surface of a pond or river while in flight. Some species like the common nighthawk are often seen

scarfing up insects around artificial lights like street lamps and the lights of buildings. But what happens when the hunter becomes the hunted? What kind of predators pose a danger to night jars? These are ground nesting birds, so they face significant threats from ground-based carnivores. In North America, mammalian predators include coyotes, skunks, raccoons, and opossums. Domestic dogs and cats are particularly dangerous, pretty much throughout the world. Avian predators, such as crows, jays, and owls, also consume eggs and young. Likewise for snakes. Even insects can be dangerous. Invasive fire ants have been observed preying on common parake eggs, and these ants may be contributing to the declines of nightjar species

on some Pacific islands. To escape the notice of all these predators, a capromulgid bird disguises itself as an unassuming pile of leaves on the ground. That strategy probably works most of the time, but it backfires in an encounter with the night jar's greatest nemesis, the leaf blower. Rather than ignoring a pile of leaves, the ferocious leaf blower actively seeks them out as prey. The leaf blower roars obnoxiously as it blows with its mighty breath to disperse and therefore annihilate any cluster of leaves that lie in its path. Any unlucky nightjar in the leafblower's path of destruction is revealed for what it is.

The bird suffers a mild annoyance, and it feels compelled to fly away and relocate. Now let's look deeper into how birds in this family make babies. How do night jars breed? Due to their nocturnal slash crepuscular habits, cryptic plumage, and often camouflaged eggs, there's still a lot we don't know about the breeding habits of many species. But let's talk about some things we do know. Most of these birds are monogamous,

with both sexes helping to raise chicks. But there are some outliers. For example, the genus Europe Salus includes South American species that appear to be polygynous. I mentioned them earlier. We were talking about the lyre-tailed nightjar and swallow-tailed nightjar. The males have those super-long ornamental tail feathers. They display for females in communal lecks. And in their lecking behavior, the males call, circle, or chase females in flight.

Remember that polygyny is a mating system where one male mates with multiple females during a single breeding season, but each female typically mates with only one male. In Africa, male standard-winged night jars and pennant-winged night jars also appear to be polygynous. Males gather at display arenas or lex in open spaces, with a lot of interactions occurring on the ground and in the air, males display to females by flying around them with calls before they land. There can be dozens or even hundreds of night jars gathered together at these Leck sites. So these are courtship displays that we're talking about, and monogamous species also have courtship displays.

According, male often performs some kind of aerial display, accompanied by vocalizations and maybe some of those non-vocal mechanical sounds. The booming sound of the common nighthawk that we talked about serves a function similar to song in marking an exclusive territory. Male nighthawks typically perform these displays in areas close to their nests. Courtship and mate selection in this species occur partly in flight. The female may be in flight or stationary on the ground during the male's dive slash boom. Let's listen again to the boom of the common nighthawk. After diving, the male lands on the ground in front of the female.

He spreads his wings and wags his tail while puffing out his throat to show off his white throat patch. Meanwhile, he makes some guttural croaking calls. This courtship display is repeated until the male and female finally seal the deal and copulate. So night jars of all kinds pair up, mate, and then it's time to make a nest and lay some eggs. Well, it's time to lay eggs, at least. Make a nest? Yeah, not so much. Because birds in this family just drop their hot little eggs directly on bare ground or maybe on some leaves.

They don't make a nest, and they don't generally even make a scrape. But they're still careful about where they put the eggs. The actual site characteristics vary widely depending on the species and habitat. Examples include areas under dense cover near old roads, or forest edges, or near specific trees like cedars or pines. They may also nest in brushy habitat on rocky or sandy slopes, under overhanging rock outcrops, at the base of a cactus, against open rocks, or in grassy tufts. Nightjars may also make their quote-unquote nests in human modified habitats like cultivated fields, on fence posts, or rooftops. Nighthawks are particularly known for nesting on

flat gravel roofs, especially in cities, although this habitat is apparently declining due to changes in the way buildings are constructed. A typical clutch contains just one or two eggs. The shells are well camouflaged, usually light-colored with some darker blotches and spots. Both parents take turns incubating the eggs and feeding the youngsters. When threatened at their nest sites, night jars exhibit various defensive behaviors. A common response involves hissing and opening their mouths in a threat display. For instance, common nighthawks hiss or give throaty clucks, and if approached, they may aggressively vocalize with an open mouth,

fluff their feathers, raise their wings, and continue hissing. Nestling nighthawks too employ hissing as a defense mechanism. To lure predators away from their vulnerable eggs or young, several nightjar species perform distraction displays. For example, Chuck Will's widow might fly low, repeatedly drop to the ground, hiss, or droop its wings, and common poor wills sometimes feign injury with a broken wing display, or they use flopping and tumbling around on the ground as distractions. The chicks are semi-precocial when they hatch.

They're typically covered in down feathers, and their eyes are open or, partly open at hatching. The down coloration varies by species, but it's always cryptic, camouflaged. It helps the little guys blend in with the substrate. The semi-precocial chicks are generally active after hatching. They can move around a bit on their own. They fledge somewhere between 16 and 23 days after hatching. The youngsters stick around with their parents for a while after fledging, and full independence occurs after maybe another two-week or so. There's not a lot of solid data on lifespan in these birds. Banding studies on common nighthawks, however, show that they live at least four to five years, with some birds reaching

maybe nine years. It's possible that night jars, in general, are not especially long-lived birds. Among my first memories of getting to know these mysterious birds, I remember I remember driving slowly along a dirt road at night in the desert. Every few minutes, the headlights of my truck would reveal the glowing eyes of a small brown creature sitting on the side of the road, or in the middle of the road. It would stay motionless until the last moment when suddenly it transformed into a bird and fluttered off into the darkness. I was intrigued and charmed by these creatures, which turned out to be common poorwills. They seemed to have a kind of benevolence and meditative composure. I was happy to see one after another of these little buddies as I drove along that dusty road. Since then, I've been lucky enough to encounter many species in the family Capramalgadi, seeing them and hearing them, as silhouettes swooping through the twilight, or sitting motionless at their daytime roosts. It's always a thrill. I really hope that you too get to see and hear some of these enigmatic, wonderful birds.

Thanks for hanging out with me today for episode 116. I really enjoyed doing this deep dive into the biology of Capramulgids. There are still plenty of gaps in our scientific knowledge about them, so hopefully ornithologists will discover more about them in the years to come. Thanks, as always, to my amazing supporters on Patreon for making this podcast possible. And a big thank you to those of you who signed up as support. since the last episode. Welcome Alan Dills, Mamie Brower, Susan Axebronk, Allison, Barbara, Grant Livingston from Miami, Leah, Iko, Dave and Dolores, Catherine Garvey, Christel Banzies, and Charlie. Thank you all so

much. If you are not yet a supporter but are interested in keeping the episodes flowing, you can check out the support the show link in the show notes in your podcast app. Or you can go directly to my Patreon page over at patreon.com slash science of birds. And don't forget, as a member of my Patreon community, you get access to perks like voting in polls, as well as behind-the-scenes posts and videos and so on. Please go ahead and shoot me an email. Maybe you have a comment about the podcast, you want to share a story about an encounter you had with a nightjar,

or you want to nominate some other animal species that we should rename as diabolical, satanic or something similar. Like, I've got a few. How about the satanic hamster? Or the diabolical dolphin? Or the unholy panda? I don't know. I'm still brainstorming,

but as for my email, my address is Ivan at Scienceofbirds.com. Again, this is episode 116. You can check out the show notes along with some curated photos of night jars I talked about today on the Science of Birds website, scienceofbirds.com.

I'm Ivan Philipson, and true fact about me, I have a habit, some might say a bad habit, of collecting rocks. My apartment is littered with rocks that I've picked up on my travels. Some of them are pretty heavy, because when I visit a country, one of the best and certainly cheapest souvenirs I can find is a cool-looking rock. And I do my best to remember where it was that I found it so that I have a little memory and story associated with that rock. Anyway, thanks again for listening.

Cheers.