The Science of Birds - Roadrunners

Episode Date: September 1, 2021

This episode is all about the bird species in the genus Geococcyx. There are only two: the Greater Roadrunner and the Lesser Roadrunner. People in North America have revered the Greater Roadrunner for thousands of years. This bird features prominently in Native American and Mexican legends and lore. It’s usually depicted in a good light. Roadrunners are bold, clever, and fast—all admirable characteristics. They’re also large and conspicuous birds, so it’s not surprising that more than one culture has paid them some special attention.Learn about the key traits of roadrunners and their habitats, diet, and breeding.~~ Leave me a review using Podchaser ~~‍Links of InterestVideo: Roadrunner catching a hummingbirdVideo: Roadrunner vs RattlesnakeLink to this episode on the Science of Birds websiteSupport the show

When I was 11 years old, my elementary school held a contest to choose a new logo design. Our school mascot was a roadrunner. This was in rural Southern California, where you sometimes see these birds darting around in dry scrubby habitats. Up to that point, the school's logo was an illustration of a roadrunner that looked, well, I'd say, pretty familiar to anyone who's watched TV in the last 60 years. Meep, meep. I guess copyright infringement wasn't such a concern back in the 80s. Ah, those were simple times. For this contest, any student could submit their own design for the new logo. I was an artistic kid, and I jumped at the opportunity to put my skills to the test.

I was going to win this thing, dang it. You could enter as many logo designs as you wanted, and I ended up submitting half a dozen or so. I didn't take the predictable, uninspired approach of simply tweaking the existing school logo. I didn't just slap a fresh coat of paint on the old rip-off Looney Tunes Roadrunner. I wanted to draw a more realistic roadrunner, like the actual bird, because even as a naive little sixth grader, I was already keenly interested in science and natural history. So, long story short, I won the contest. I was super proud and excited.

My Roadrunner was soon splashed across the front of t-shirts worn by my teachers and classmates all around the school. It was featured on school stationary, on banners, and all that sort of stuff. How good was my Roadrunner drawing? Was it more biologically accurate than its predecessor? I called my mom recently, and amazingly, she was able to dredge up a copy of my old logo from a dusty box in her garage. I'll post the artwork on my Patreon page, so that's a little bonus content my supporters will have access to. Anyways, my drawing was okay. I mean, artistic talent or not, I was only 11 years old. My Roadrunner looked more like the real bird than the Looney Tunes character, I'd say,

but it was a long way from being a professional illustration. The school used my logo for some years after I left. Such was my legacy. But it disappointed me to discover that the next time the logo was redesigned, they went right back to using a second-rate Looney Tunes Roadrunner. Lame. Such is the power of pop culture, I guess. Presumably, the Roadrunner was originally chosen to be my school's mascot because this large charismatic bird was seen running around in the fields near the school. But by the time I was a student there in the 80s, roadrunners had become scarce in the immediate area. Much of the bird's habitat had been converted to farmland. I, in fact, had never seen a wild roadrunner when I made my drawing for the logo contest. Neither had most of the other kids or

teachers, I'm guessing. To them, the only roadrunner they could picture was the one on TV. Years later, when I was all grown up, I returned to my hometown. I was a biologist by then. I finally came face to face with a wild roadrunner in a wildlife preserve not far from my old elementary school. It was a meaningful, touching experience for me, and I could have sworn that bird gave me a nod and a knowing look. That experience was a long time ago now, maybe 20 years ago. As I started working on this episode, I worried about the current status of roadrunners in those fields where I grew up. Are they okay? Are they still there? It didn't take long for me to get some answers.

If you listen to my recent episode on E-Bird, you know that E-Bird is a great tool for sleuthing out where birds have been sighted by birders. So I just went to the E-Bird website, clickety-click, and what do you know? There are still roadrunners on the outskirts of my hometown. People have reported seeing them this very month, in fact. My Roadrunner logo may have been replaced long ago and forgotten,

But I'm happy to know the birds themselves are alive and kicking in Southern California and throughout the American Southwest. Hello and welcome. This is the Science of Birds. I am your host, Ivan Philipson. The Science of Birds podcast is a light, guided exploration of bird biology for lifelong learners. This episode is all about roadrunners.

These are bird species in the genus Geo-coxics. There are only two, the greater roadrunner and the lesser roadrunner. Ornithologists know much more about the biology of the greater roadrunner, and this is a more familiar bird to most of us, so most of our discussion today will focus on that species. People in North America have revered the greater roadrunner for thousands of years. This bird features prominently in Native American and Mexican legends and lore. It's usually depicted in a good light.

Roadrunners are bold, clever, and fast, all admirable characteristics. They're also fairly large and conspicuous birds, so it's not surprising that more than one culture has paid them some special attention. And here we are. giving roadrunners some special attention. So let's hit the road and learn about these fascinating birds. The scientific name of the greater roadrunner is geocoxics Californianus. The alternatives you may have seen in cartoons like acceleratite incredibus and velocitus

in calculus. While they may sound sciencey and legit, you can't always trust what you see in cartoons. The real name is geocoxic's Californianus. This is a large and slender bird. From beak to tail, it's about 23 inches long, or 58 centimeters. The roadrunner's grayish-brown bill is long, strong, and hooked at the tip. The bird sports a blue-black crest of feathers on its head. The crest can be raised or lowered, depending on the bird's mood or what it's trying to communicate. The long tail, too, is raised and lowered expressively. Around and behind its pale eye, the Greater Roadrunner has a visible patch of bare skin. It's about 1.2 inches or 30 millimeters long. The skin is indigo blue or sky blue near the eye, but fades to white and then red

in the posterior direction. A roadrunner can expose or conceal most of this skin by moving the small feathers that surround the bear patch. A bare patch of skin between the feathers of a bird is called an aptarium, A-P-T-E-R-I-U-M. Aptaria is the plural form. So this aptarium around the eye of the roadrunner is red, white, and blue, very patriotic,

which is, little-known fact, exactly why Benjamin Franklin argued the roadrunner ought to be the national symbol of the United States, rather than the bald eagle. That is, sadly, not true. But you know what else isn't true? The similar and oft-repeated story about Ben Franklin making a case for the turkey to be our national bird. That didn't happen. He did trash-talk the bald eagle, yes, and he did extol the virtues of the wild turkey. But Franklin never publicly proposed that America should be represented by the turkey. But how cool would it be if the Roadrunner had ended up as the bird on our coins, bills, and national seal? I'd vote for that. And okay, so some might say the quote-unquote red color on the back end of the Greater Roadrunner's Aptarium is really more of an orange. Sure,

maybe. But I already made my stupid red, white, and blue joke, so now we all just have to get on with our lives, okay? As for the plumage of the Greater Roadrunner, it's streaky brown or olive overall, intermixed with pale buff or white accents. The darker parts of the feathers have a glossy, bronze-green iridescence that gleams in the right lighting. The long-tail feathers also show some lovely blue iridescence. Male and female roadrunners are mostly indistinguishable, at least to us simple-minded primates. The sexes may show some subtle color variation in the skin of the aptarium, that bare patch behind the eye, and females are a bit smaller than males. But otherwise, roadrunners are sexually monomorphic.

They have one form, which is another way of saying they are not sexually dimorphic. Roadrunners have long legs with toes arranged in an X pattern, two toes face forward, two face backward. We see this arrangement in some other birds like woodpeckers. It's called zygodactyl. Most of us are more familiar with the three toes forward, one toe backward, or anisodactyl arrangement. No other ground-dwelling birds in the southwest have zygodactyl feet. So if you see bird tracks that look like a series of little X's, you know you're on the trail of a roadrunner. But that X-shaped footprint makes it hard to know which way the bird was heading. That's one reason why the Pueblo people, Native Americans of the Southwest, considered the X-shaped footprint of

the roadrunner to be a sacred symbol. They believed that an evil spirit couldn't follow a roadrunner because it couldn't tell if the bird was coming or going. With those long, strong legs and toes, road runners do, in fact, run. These are speedy birds, and yes, they run on roads. But long before humans came along and built roads, roadrunners were zipping along dry stream beds, gullies, and other naturally occurring open pathways. I suppose roadrunner rolls off the tongue a little better than dry streambed runner. A greater roadrunner routinely darts around at about 15 miles per hour, which is 24 kilometers per hour. In short bursts, like when it's sprinting after a lizard, a roadrunner may hit 20 miles an hour or 32 kilometers per hour. It's one of the fastest

running birds in the world. For comparison, the world record for the fastest human runner is 27.5 miles per hour, only a little faster than our roadrunner. And in case you're wondering, a coyote can run up to 43 miles per hour, which is 69 kilometers per hour. So wily coyote didn't need all those contraptions to catch the roadrunner. He'd have had better luck just chasing the bird on foot. When moving at its fastest, the roadrunner lowers its head and its tail so that these are parallel to the ground. If it needs to make a sudden change in direction, the bird swings its tail to the side. This acts as a counterbalance or rudder, allowing the roadrunner to turn on a dime, so to speak. The superb running ability

of the roadrunner contrasts with its relatively weak ability to fly. Its wings are rounded and on the short side. These birds rarely fly more than a short distance, in little bursts. You're not going to see any roadrunners soaring majestically through the clouds high overhead. These are ground dwellers. The greater roadrunner thrives in arid and semi-arid habitats. I most recently saw one in Saguaro National Park outside of Tucson, Arizona. The air temperature at 8.30 a.m. was already about 90 degrees Fahrenheit, which is 32 degrees Celsius. What was this roadrunner doing? It was crossing a road, of course.

The ground temperature experienced by the bird on that pavement would have been significantly hotter. I only got a quick look before the roadrunner dashed off, disappearing into the cactuses and thorny shrubs on the roadside. What traits allow a roadrunner to live in dry, hot places like Arizona? First off, it has several physiological adaptations, the ability to get most of its water from its prey, for example. rodents and lizards can provide all the water a roadrunner needs for long periods, but the bird will happily guzzle water when it's available.

To keep its brain and eyes from boiling on a hot day, a roadrunner has a sort of heat exchange system in its head. This is a complex network of arteries and veins that work to move heat away from the head. The technical name for this network of blood vessels is Ridiophthalmicum. Roadrunners also keep their cool by panting and with Guller fluttering. Guller fluttering is where the bird opens its mouth and moves or flutters the skin on its neck rapidly to dissipate heat. Temperatures in the desert can sometimes swing dramatically over the course of 24 hours. On a day where it's baking hot at noon, the temperature that night might plummet to near freezing.

Roadrunners adjust their daily activity accordingly to spend, the least amount of energy to survive. So they're most active between sunrise and about 10.30 a.m. When it's not so hot. They find a shady refuge during the heat of the day. On chilly nights, a roadrunner will sometimes go into a state of torpor. We've talked about torpor before on the podcast. This is where a bird slows down its heart rate and lowers its metabolism to conserve heat and energy. It's a sort of short-term hibernation. A roadrunner's body temperature can drop about 10 to 15 degrees Celsius while in torpor. To warm back up in the morning, the bird will often bask in the sun for an hour or more.

It spreads the feathers on its back to expose a patch of bare black skin. This absorbs the sun's warmth and transfers it to blood vessels just below the skin. So this patch of black skin is another example of an aptarium. Now, as for the sounds a greater Roadrunner makes, sorry, but it does not make this sound. Meep, meep. Forget you ever heard that. Roadrunners don't go, beep, beep.

Tell all your friends, they don't do that. Real Roadrunners make about seven distinct vocal sounds. The one we hear most often is a sort of cooing, made by the mail only, and it goes like this. Here's another example. Other sounds made by these birds are described as barks, whirrs, wines, and growls. Roadrunners also make a couple non-vocal sounds.

For example, they snap their bills together rapidly, making a sort of castanet sound, like this. Now, I hope you didn't forget about the lesser roadrunner. This bird, geocoxic's V-locks, looks a lot like the greater roadrunner we've been talking about. But the lesser roadrunner has a shorter bill, and its plumage is less streaky. And this may come as a shock to you, but the lesser roadrunner is smaller. It's only about 18 inches long, which is 45 centimeters. You know, these names, lesser and greater, what's the plan if we ever discover a roadrunner species that's somewhere in the middle?

Like larger than a lesser but smaller than a greater? Would we call it the average roadrunner? The unexceptional roadrunner? The middle of the roadrunner? perhaps? The genus name geocoxics translates as ground cuckoo. Roadrunners are exactly that,

members of the cuckoo family that spend most of their time on the ground. Within this family, cuckoolidae, the closest relatives of our roadrunners are thought to be birds, in the genus neomorphous. There are five species in this genus. We call them ground cuckus. There's the red-billed ground cuckoo, banded ground cuckoo, and so on. These elusive birds skulk around in the forests of Central and South America. So, even though the Roadrunner

genus Geocoxics means ground cuckoo, we don't call them that in English. There are these other birds that we do call ground cuckus, but there in the genus, neomorphous. On top of that, there are several Asian ground cuckus that aren't even close relatives of the roadrunners or the ground cuckus of South America. Kind of confusing, I know, but what are you going to do? Members of the cuckoo family are found all across the planet, but as far as we know, roadrunners evolved in the new world. They're unique to the Americas. The oldest fossils of birds that were clearly roadrunners date to about three. 33,000 years ago and were found in New Mexico.

Roadrunners weren't always so specialized for life in the desert. Until about 8,000 years ago, it seems they lived in woodlands and open forests. As the surrounding climate became more and more arid, the birds then adapted. The greater roadrunners range spans the southwestern U.S. and northern Mexico. The species has been expanding to the north. and east in recent decades. This might be because overgrazing and forest clearing have created more of the scrubby open habitats that roadrunners prefer. Dense forest and winter snow might ultimately limit the northward expansion of roadrunners. These birds aren't very tolerant of

severe winters. However, as the climate continues to heat up, no thanks to humans, we might see roadrunners moving farther and farther north. The lesser roadrunner lives in western and southern Mexico, as well as parts of Central America. The two species are both year-round residents in their habitats. In other words, they do not migrate. The greater roadrunner prefers habitats with open space and plenty of shrubs around. Depending on the region and elevation, the dominant shrub might be creosote, mesquite, or juniper. You'll sometimes find roadrunners in grasslands, farmlands, or areas with some suburban development. Development causes habitat destruction and fragmentation, and this is probably the biggest threat

to the greater roadrunner. Dense urban areas don't have enough food or nesting habitat for roadrunners. Thankfully, it seems the species is doing okay in the grand, scheme of things. It has a large range and a large population. The IUCN puts the greater roadrunner in the least concern category. Same goes for the lesser roadrunner. But some populations of the greater roadrunner aren't doing all that well. Those in Southern California, where I grew up, have been in decline for several decades. That's why it was a relief when I looked at Ebert and saw that people are still finding roadrunners in my hometown. But who knows how long they'll be able to

survive there? Besides habitat destruction, threats to roadrunners include illegal shooting, predation by cats and dogs, and collisions with cars. Roadrunners are omnivores. Like humans, bears, and pigs, roadrunners have a varied diet. These birds are opportunistic to the max. They eat lots of insects, spiders, scorpions, and millipedes. They also excel at catching and devouring lizards and small snakes. Roadrunners will eat anything else they can catch and hork down their gullets. This includes rodents, frogs, birds, eggs, and some plant material, like cactus fruit. And the list doesn't stop there. Given the opportunity, a roadrunner will eat dog food, dead animals, garbage,

and sometimes their own babies. Geez, what don't these birds eat? I wouldn't be surprised to hear they also eat beer bottles, double-a batteries, and baby diapers. Anyway, roadrunners are famous for killing and eating snakes, especially rattlesnakes. When facing off against a rattlesnake, a roadrunner hops around, flaps its wings, and dodges when the snake strikes. The bird is incredibly agile and fast. It spreads its wings to distract the snake, like a bullfighter using a red cape. It pecks at the snake's head repeatedly until it can grab the reptile by the neck. Then, using its bill, the roadrunner slams the snake's head against the ground again and again until the snake is limp and lifeless.

Two roadrunners will sometimes work as a team to take down a larger snake. One distracts the snake while the other tries to sneak in and grab it by the head or neck. This is a risky way to score your lunch. Roadrunners are vulnerable to rattlesnake venom. If a rattler sinks its teeth into a roadrunner, that's probably lights out for the bird. This trick of swinging prey through the air and slamming it against the ground is used on more than just rattlesnake. roadrunners slam lizards and rodents on the ground too. The bigger the prey, the more slams it gets at a rate of about 21 per minute. This not only stuns or kills the prey animal, it also breaks

its bones and sort of tenderizes the meal, making it easier to swallow. Roadrunners love to gobble up small birds. They snatch baby birds out of nests, they stake out feeders, and raid nest boxes. The roadrunner is one of the few animals that's actually sneaky enough and fast enough to prey on hummingbirds. They sometimes ambush hummers at feeders. But this is no easy feat. For example, the estimated success rate for one particular roadrunner was only one in ten. But I guess it's worth the effort. Hummingbirds may be small, but they eat nothing but sugar all day.

So to a roadrunner, a hummingbird might taste like sweet, sweet candy. like a gumdrop or a jelly bean. I mean, who knows? I'll put a link in the show notes to a slow-motion video of a roadrunner snatching a hummingbird in mid-air. It's a pretty crazy thing to see. We know a lot less about the diet of the lesser roadrunner.

This bird probably preys on mostly invertebrates like grasshoppers, as well as some small vertebrates. So we've established that roadrunners are basically garbage guts. They eat just about everything, right? But who eats roadrunners? Who are their predators? And this is where someone in the audience yells, Coyotes! What about coyotes?

We already established that a coyote, technically, should be able to catch a roadrunner in a straightaway sprint. But roadrunners can and do turn quickly and evasively while running away. A roadrunner being chased by a coyote probably isn't going to run in a straight line down the middle of the road, despite what you've seen in cartoons. In real life, the bird will zig and zag and use the cover of shrubs to escape, and in a pinch it can flap its wings and fly away a short distance. Interestingly, no one has ever reported seeing a coyote actually catch a roadrunner. But feathers and bones of roadrunners have

been found in the stomachs of dead coyotes and in coyote's scat. So at least every once in a while, a roadrunner gets caught. The only other major predators of adult roadrunners are raptors like the red-tailed hawk and Cooper's hawk. But don't forget that domestic cats and dogs are also a menace to roadrunners. Snakes and some small mammals will eat roadrunner eggs and nestlings. If the roadrunner parents find a predator lurking near their nest, they sometimes pretend to have a broken wing or leg, to attract the predator's attention and lure it away from the helpless nestlings. And speaking of nestlings, let's move on now to talk about how Roadrunners reproduce. The Roadrunner is a solitary creature in general, but it spends

a significant portion of the year with its significant other, its mate. courtship, nest building, incubating the eggs, feeding the little ones, raising a roadrunner brood can take all spring and summer. Roadrunners are monogamous, and they form long-term pair bonds. That bond needs to be renewed every spring. This is accomplished with energetic and elaborate courtship behaviors. The male and female chase each other around for hours. The male dances for the female, bowing and jumping and wagging his tail. He makes cooing calls for her, and they both make clacking sounds with their bills. The male also offers sticks to the female, or presents her with other gifts like a dead lizard or grasshopper. Having reinforced their

bond, the two birds establish and defend a large territory together. They forage for prey together and eventually build their nest. It's the female who does the construction work, but the male brings her the sticks she needs. The nest is a platform of tightly packed sticks, lined with grass, feathers, cow manure, or even snake skin. The roadrunners place their nest in a small tree, a thorny bush or cactus, about three to ten feet or one to three meters above the ground.

Now, roadrunners are cuckoos, right? You may recall that cuckus are notorious for being brood parasites. I did an entire episode on brood parasitism. That was episode 12. Check that out if you haven't already. Anyway, this is the reproductive strategy of laying your eggs in the nests of other birds and letting them raise your babies for you. But not all members of the cuckoo family are brood parasites. Our roadrunners don't seem to do this very often. There's some evidence from like a hundred years ago that greater roadrunners laid eggs in a common raven nest and a northern mockingbird nest. These would be examples of interspecific brood parasitism,

laying your eggs in the nest of another species. There's also some evidence that roadrunners will parasitize the nests of other roadrunners. Ornithologists have found roadrunner nests containing more than 12 eggs. That's too many for one female to lay on her own. So maybe roadrunners practice a little bit of intra-specific brood parasitism too. But parasitism like this seems to be the exception rather than the rule for roadrunners. Once the eggs are laid, usually a clutch of three to six, both the male and the female share in the duty of incubation. The male has the night shift, though. He says, on the eggs all night. Remember that roadrunners can drop their body temperatures on chilly

nights? Well, a male sitting on his eggs doesn't do that. He doesn't go into torpor since the eggs need to be kept warm at a constant temperature. After the eggs hatch, mom and dad both feed and protect the growing chicks. The family of roadrunners forage together until the young are about 40 days old. Sometime before they're two months old, the juveniles get chased off by their parents. Then they're on their own. Roadrunners live adventurous lives. They dodge speeding cars, lunging rattlesnakes, and salivating coyotes.

They eat scorpions and hummingbirds, and they confuse evil spirits with their X-shaped footprints. Roadrunners are opportunists, risk-takers. It shouldn't surprise us then. and to learn that most of them live only a few years. The oldest wild roadrunner on record was only seven years old. It seems that roadrunners live fast and die young. Maybe you see roadrunners in your backyard all the time.

If so, consider yourself lucky. Or maybe the only roadrunner you know anything about is the animated Warner Brothers character. beep, beep, and all that nonsense. Whatever your experience with these birds, I hope you learn something new about them in this episode. And I hope you had some fun along the way. My wonderful patrons on Patreon support my work in making these episodes.

So here's a wholehearted shout out to my newest patrons, Emily, Michelle, Ravi, and Debbie. Thank you, thank you. I so appreciate your support. If you, my friend, have some interest, in supporting this podcast, you can check out my Patreon page at patreon.com forward slash science of birds. You can also shoot me an email if you have something you'd like to share with me.

Maybe your thoughts about the podcast, about your elementary school mascot, or about your method for keeping your brain from boiling on a hot day. In any case, my email address is Ivan at scienceofbirds.com. You can check out the show notes for this. episode, which is number 34, on the Science of Birds website, science ofbirds.com. This is Ivan Philipson, wishing you a lovely day. Peace.