Why do roadrunners disappear from the desert each winter?

These birds can't migrate, but local ecologist has a possible answer

James W. Cornett
DESERT [Sun] magazine

No bird is so odd and well known as the roadrunner. Unlike most birds with which we are familiar, a roadrunner runs rather than flies, readily embraces humans and, as a predator, feeds on some of the most unappetizing animals imaginable including scorpions, black widows and rattlesnakes.

There are two kinds of roadrunner: a small one called the Lesser Roadrunner, Geococcyx velox, and a big one known as the Greater Roadrunner, Geococcyx californianus. The Greater Roadrunner is the one with which we are familiar, in part, because of Warner Bros. “Roadrunner” cartoon series memorable for the ever-pursuing adversary, Wile E. Coyote. The Lesser Roadrunner is a Mexican species whose nearest population lies in the state of Sonora, 300 miles from the U.S. border. Other than its weight of 8 ounces (two-thirds that of its larger cousin), nothing is known about it.

Prefers to run rather than fly

There is no doubt our roadrunner prefers to run rather than fly. Over the years my daughters, co-workers and myself have raised dozens of roadrunners from eggs and hatchlings – brought to us as orphans by valley residents. Hatchling roadrunners grow rapidly on a diet of mealworms, crickets and commercially available frozen mice. Within four weeks they reach adult size.

With access to free and cooperative subjects, I was able to take photographs of roadrunners in novel situations. I particularly wanted an image of a roadrunner in flight, impossible to obtain in the wild and no easy feat even when working with tame birds. Enlisting the aid of my oldest daughter, Mandy, I had her toss birds into the air assuming they would flap their wings and glide for a short distance. With every toss, however, each roadrunner glided immediately to the ground and so fast I could never get a photograph. Mandy suggested she throw the bird over the local, community pool. This worked since each roadrunner was obviously born with an aversion to landing on water. It was forced to flap its wings several times, then glide to the edge of the pool. Using the technique, I finally got the photograph I desired as the bird remained airborne for several seconds.

Roadrunners as fliers

Roadrunners are not just gliders but can fly, albeit poorly. They occasionally flap their wings for a few seconds, reach an altitude of 10 feet, then glide to a landing. I have never seen a roadrunner make two successive flights and doubt they can. An examination of a roadrunner’s skeleton reveals no keel on the breastbone as is found in birds capable of flight. (The keel is a bony ridge that grows from the sternum. It’s the point of attachment of large pectoral muscles necessary for prolonged flight.) With tiny pectoral muscles, sustained flight is impossible and even sustained gliding is difficult. The greatest glide time I witnessed was in the Chisos Mountains of Big Bend National Park. From the Lost Mine Trail, a roadrunner launched itself off a ledge and glided for 12 seconds down into a canyon, a vertical descent of 500 feet.

How fast?

“How fast can a roadrunner run?” is a question I am often asked. The top speed given in the literature is 18 miles per hour. I put the top speed closer to 20 based on a roadrunner running alongside my vehicle for a short distance. In either case, a roadrunner’s speed is less than half that of a race horse. Winning Brew reached nearly 44 mph at the 2008 Penn National Race Course in Grantville, Penn. A roadrunner’s top speed is also less than a human sprinter. Usain Bolt, the Olympic gold medalist from Jamaica, was once clocked at 27 miles per hour. Despite comparisons, the much smaller size of the roadrunner enables it to reach top speed faster than a horse or human, and my money would be on the roadrunner in a 10-yard sprint. It is also more maneuverable and, using its wings and tail as breaks and rudders, can change direction in an instant; a critical ability when chasing lizards and other small, fleet-footed animals.

As a predator

The diet of a roadrunner is limited by three factors. Prey must be alive and moving, not too large to be subdued and not poisonous. Thus, dead animals are off limits as are large animals that weigh more than a pound. The big black Eleodes beetles and all toad species are not consumed since they are poisonous. (A poison is a toxic substance that enters the body passively, usually when swallowed. A venom is a toxic substance actively injected as when a person bitten by a spider or venomous snake. Poisons can kill if swallowed. If venoms are swallowed, they are broken down into harmless components during the digestive process.)

A roadrunner’s diverse appetite should make it a welcome addition to any neighborhood. Crickets and cockroaches are routinely consumed. The shells of garden snails offer no protection as a roadrunner smashes them against a hard surface, flings away shell fragments and swallows the torso in one gulp. My wife is particularly fond of our local roadrunner’s willingness to pluck black widows off their webs, crush them in its beak and swallow entire spiders.

I must confess there are some creatures most homeowners prefer a roadrunner not eat. Nestling songbirds are consumed as are their parents, if they can be caught. There is at least one record of a roadrunner leaping into the air to capture a hummingbird. I never dreamed fast-flying (and mosquito-eating) dragonflies could be snapped up by roadrunners but now have seen this happen four times in my own yard. Lizards were once common around our home, but not anymore. For the first time last spring, a roadrunner built a nest and raised a brood of four chicks in a shrub at the side of our home. By the time the young left the nest, every spiny, whiptail and side-blotched lizard within 100 feet of our yard was gone.

The snake eater

A roadrunner’s propensity to eat snakes, most importantly venomous species, dramatically enhances their image among laypersons and at least partially makes up for the culinary digressions described above. For the record, a roadrunner approaches any snake as though it were venomous, and no roadrunner is immune to the bite of a venomous snake. If bitten, and venom injected, a roadrunner dies. Nonetheless, there is no roadrunner alive that will not attack and kill a small rattlesnake. Victims are generally less than 18 inches in length, though much larger rattlers will by harassed by yanking on their tail.

A roadrunner is too fast and too agile to be bitten by even the fastest-striking rattlesnake. A roadrunner approaches a rattler with wings and tail spread wide, using them as a decoy much like a bull fighter uses a cape. The function of the display is to elicit a strike which the roadrunner avoids by leaping into the air. After several strikes, the roadrunner gauges the length and speed of the snake’s defense and readies itself for the kill. In the middle of the strike, when the snake is most extended, the roadrunner grabs the head in its mandibles and repeatedly pummels the snake against the ground. After battering, the vertebral column is broken in multiple places and the rattlesnake is effectively paralyzed.

A roadrunner’s mandibles don’t have sharp edges and it lacks the powerful talons of a hawk. Prey can’t be torn into pieces and so must usually be swallowed whole. Long animals, such as whiptail lizards and snakes, must be swallowed in stages. It may take well over an hour before the entire animal disappears down the roadrunner’s throat. It is not unusual to see a roadrunner running about with the tail of a snake or lizard hanging from its mouth.

A hibernator?

I first became seriously interested in roadrunners when, time after time I was asked, “Where do roadrunners go in winter?” Of course, they don’t go anywhere since, as poor fliers, they can’t migrate. (I have never heard nor seen roadrunners running south for the winter.) My own field notes, however, do indicate roadrunners are observed much less in winter. In addition, desert residents often relate how a roadrunner visited them daily through spring, summer and early fall. Then, rather suddenly in late fall, the bird’s daily appearances become less consistent or, more typically, stop altogether. What happens to roadrunners in winter?

One possible explanation is roadrunners hibernate. Roadrunners, unlike most other birds, enter torpor every night and allow their body temperature to drop significantly. It is conceivable that some birds extend this torpor in winter to days, weeks or even months to save energy when food is less available. There is, after all, one bird species known to hibernate: the common poor-will, Phalaenoptilus nuttallii, that I wrote about a few months ago. Might the roadrunner be a second species? No roadrunner has been found in torpor for even a single day much less the entire winter. Finding such a bird during the daytime would be a strong indication that at least some roadrunners hibernate.

Roadrunners and humans

Encounters between humans and roadrunners are both frequent and diverse. For example, it is not unusual for roadrunners to follow hikers, particularly in state and national parks where people are likely to be on their best behavior. Lest a human mistakenly believe a tag-along roadrunner wants to make friends, be aware the bird is most likely hungry and on the lookout for an easy meal. To a roadrunner, even the smallest among us is a lumbering mammal capable of stirring up insects and reptiles as we walk down a trail. Roadrunners follow us just as they might a steer or horse.

My most memorable encounter with roadrunners involved a British broadcasting crew who wanted to film their behaviors. Before making the trip from London, however, they needed assurances the birds would appear and they could film them up close. I told them it was very likely the birds would show up since we were conducting feeding experiments and the birds appeared every morning for free handouts. I was not sure they were convinced but, nevertheless, arrived a few weeks later. I had them transfer their gear to my SUV, so the birds would not be frightened by a strange vehicle. We could neither see the birds nor hear the clattering of their bills as we drove slowly down the road towards the study site. Then, suddenly, the male and female ran out of the desert, launched themselves through the open windows and into the vehicle – while we were still moving! The birds perched briefly on the shoulders and heads of film crew members as they investigated every corner of the interior looking for crickets and mealworms. “Is that close enough for you?” I asked, smiling.

Roadrunners in the house

Bob and Marilyn Shoemaker lived on a golf course surrounded by homes. They heard I was studying roadrunners and called to tell me a pair of roadrunners had built a nest 4 feet off the ground just outside their back door. The Shoemakers also had two small dogs that entered the backyard whenever they wished through a pet door. The dogs were intimidated by the roadrunners as they watched the birds from a distance and never moved towards them. Sometimes the roadrunners would rush the dogs, scaring them back into the house.

When I arrived, the Shoemakers suggested I sit in the living room and wait for the roadrunners to tap on the back slider.

“They do that?” I asked.

“Oh, yes, every morning,” Mrs. Shoemaker replied.

In less than five minutes two roadrunners were at the slider and started tapping on the glass with their bills. Mr. Shoemaker opened the slider and the birds immediately came in, looked around, then jumped up on the drainboard in the kitchen. On a paper plate were two dozen mealworms about half of which were quickly gathered up by the parent birds. Bills filled, the roadrunners rushed outside, jumped up into the nest and stuffed the insects into the mouths of the chicks. When finished, they came back into the kitchen snapped up the rest of the mealworms and repeated the process. The parents came back into the kitchen a third time but seeing no meal-worms left the house. They would not tap on the slider again until the next morning.

Glass tapping started after the Shoemakers began feeding the roadrunners mealworms on the patio. As the roadrunners became habituated to the practice, they started arriving before the Shoemakers went outside. The birds tried to get inside when they saw the Shoemakers in the house. Initially, they probably pecked at the glass probing for a way to gain entry. Eventually, the roadrunner pair made the connection between glass tapping, the Shoemakers’ response and getting the mealworms. The Shoemakers believed they had trained the roadrunners. But since only the roadrunners benefited directly from the relationship, it seemed to me it was the roadrunners that had conditioned the Shoemakers.

Jerry's pet roadrunners

Jerry Tyree of Sun City, Palm Desert, had a pair of roadrunners that came through his yard, almost daily. He had always fed “Suzie” and “Jerome” mealworms and crickets, and occasionally mice from the pet store. One day I asked Jerry if I could bring my students to his home to see his roadrunners. He jumped at the opportunity to show off the birds. The day we arrived he set out folding chairs on his patio facing the golf course. After greetings and introductions, we all sat down. Jerry asked that each student hold out one hand, so he could place a half dozen mealworms in their palms. He asked them to gently close their hands over the mealworms. Once prepped, Jerry called out “Suzie, Jerome” and within 30 seconds two adult roadrunners jumped atop the low wall that separated his patio from the fairway. “Open your hands,” said Jerry. As soon as the students revealed the mealworms, the two roadrunners jumped on the closest lap and proceeded to gobble down each mealworm before moving on to the next very amazed student.

Feeding roadrunners

Over the years I have met hundreds of people that feed roadrunners. Nearly every human food provider, at least initially, gives raw hamburger to the birds. A few even give beef tenderloin, erroneously believing they are providing a “better” meal. A meal of only hamburger or tenderloin is as bad for roadrunners as it is for humans, even worse if a parent bird feeds the meat to a rapidly developing chick. Most of the ingredients necessary for proper development are lacking in hamburger, resulting in growth deformities in developing roadrunners, in some cases after only a single meal.

I advise that if one insists on feeding local roadrunners, give them crickets or mealworms which can be purchased from pet stores or online. Of course, if they fill up on artificial foods, they may not eat the black widows and snails you could probably do without.