The Lyre Snake – just mildly venomous

The Lyre snake is named for a V-shaped marking on the back of the head. This marking is often more prominent on females. Dark brown saddles occur on a light brown to light gray back. The underside is creamy-white or yellow with scattered brown spots. At first glance the Lyre snake may look like the common king snake. But, the Lyre snake’s neck is narrow, making the head appear more triangular, similar to other venomous snakes. Also, the eyes have pupils that are vertical slits rather than round as are on non-venomous snakes. Lyre snakes can get up to four feet long.

The Lyre snake (Trimorphodon lambda) is usually a nocturnal hunter, but can be found basking in the sun in the spring and fall. The main prey are lizards and mice, but the snake also goes after other prey including birds (It does climb trees).

The range of this snake includes most of Southern Arizona, and extends to southern Nevada and Utah, as well as northern Mexico. It favors the lower rocky canyons and arroyos of hills and mountains from sea level to 7400 feet (2300 m). A rock dweller, it wedges itself in the many crevices and fissures that are abundant in rocky areas. This snake is an occasional resident of flat lands, according to the Arizona-Sonora Desert Museum.

According to the Tucson Herpetological Society:

Lyre snakes are not usually dangerous to humans. “When threatened, the Sonoran Lyresnake will often rattle its tail. It will sometimes raise the anterior portion of the body, and strike and bite if further provoked.” The Lyre snake does not have fangs. Rather, “Toxins produced in a Duvernoy’s gland are delivered to prey and attackers via elongated, grooved teeth in the rear of the upper jaw. A large individual is capable of delivering a venomous bite to a person. Symptoms range from none to local redness, itching, swelling, and numbness, particularly if the snake is allowed to chew.”


For more photos and a very detailed description, see an article from the Tucson Herpetological Society: .

More snake articles:

Arizona Coral Snakes – pretty and very venomous

The Coachwhip a colorful snake

Gopher snakes

Kingsnakes versus Rattlesnakes

Mexican vine snakes


Speckled Rattlesnakes


The Coachwhip – a colorful snake

The Coachwhip (Masticophis flagellum) is a fast, colorful, non-venomous, but sometimes aggressive snake that can get up to eight feet long, but most are three to five feet long. Coachwhips come in a variety of colors including tan, gray, pink, black, reddish-brown, or any combination of these colors. Broad cross bars are common. The red coachwhip is most widespread in the Sonoran Desert. A black phase occurs in Tucson and the Tucson Mountains. I saw a coachwhip in my backyard recently; its front third was black; the rest red.


These snakes range throughout the southwestern United States south through Baja California and Mexico (except the Sierra Madre) and inhabit deserts, prairies, grasslands, woodlands, thornscrub, and even cultivated lands.

According to the Arizona-Sonora Desert Museum (ASDM):

“Active during the morning and late afternoon, the coachwhip is often seen crossing roads. A speedy snake, it has been clocked at 3.6 miles per hour. The coachwhip is a nervous snake and may retreat into rocks or rodent burrows when threatened, but it is just as likely to approach an intruder hissing, striking, and possibly shaking its tail; it will bite if handled. During summer, four to twenty eggs are laid, hatching 44 to 88 days later. Young and adults feed on mammals, birds, bird and reptile eggs, lizards, snakes, carrion, and insects; the prey is seized and swallowed without being killed.”

I’ve often seen coachwhips in the aviary at ASDM where they hide in trees and prey upon birds.

There are some myths about this, and similar, snakes. According to Wikipedia:

“The primary myth concerning coachwhips, that they chase people, likely arises from the snake and the person both being frightened, and both just happening to be going the same way to escape. Coachwhips are fast snakes, often moving faster than a human, and thus give an impression of aggression should they move toward the person. The legend of the hoop snake may refer to the coachwhip snakes.”

“Another myth of the rural southeastern United States is of a snake that, when disturbed, would chase a person down, wrap him up in its coils, whip him to death with its tail, and then make sure he is dead by sticking its tail up the victim’s nose to see if he is still breathing. In actuality, coachwhips are neither constrictors (snakes that dispatch their prey by suffocating with their coils) nor strong enough to overpower a person. Also, they do not whip with their tails, even though their tails are long and look very much like a whips.”

See the Article Index page for more stories of the Sonoran Desert.

Gopher Snakes

Gopher snakes are large, heavy-bodied snakes that often pretend to be rattlesnakes. They are commonly four to five feet long but can get to over nine feet long. Gopher snakes are non-venomous and good to have around because they eat rodents.

At the Arizona-Sonora Desert Museum, keepers removed one gopher snake from the prairie dog enclosure that measured nine feet, two inches long. Guess what it was eating.

Gopher snakes vary in color but are usually yellowish, cream-colored, or tan with many black, brown or reddish blotches on their backs. Check out the top photo here to see the full length pattern. Pretty isn’t it. The scales on their back are ridged rather than smooth.

When disturbed, gopher snakes will hiss, flatten their heads, and vibrate their tails. Because of this behavior and their color pattern, they are often mistaken for rattlesnakes. As you can note from the photos below, gopher snakes have round-pupils whereas rattlesnakes have slit pupils like cat’s eyes.

Gopher Snake


Speckled rattlesnake


All you have to do is get close enough to look them in the eye to tell the difference.

Gopher snakes have a large range: all of the U.S., southern Canada, and as far south as southern Sinaloa in Mexico. These snakes can be found in deserts, prairies, woodlands, brushlands, (and in my yard), from sea level to over 9,000 feet. They are called bull snakes or pine snakes in some parts of the country.

Gopher snakes are non-venomous constrictors. They hunt during the day except in very hot weather, when they become night hunters. Their prey includes rodents, young rabbits, lizards, birds, bird eggs, other snakes, and yes, gophers. They hunt mainly by sense of smell. Gopher snakes are good climbers and can even climb a large saguaro cactus to check out what might be inhabiting those holes made by woodpeckers. Apparently their tough scales protect them from the spines.

According to the Arizona-Sonora Desert Museum, “Male gopher snakes engage in ritualistic combats during the spring mating season. The combatants remain on the ground, entwined from tail to neck. Each tries to maintain its head and body position, although occasionally they will exert so much force that they roll. Hissing frequently, they rarely bite one another. Presumably the combat ritual is a means of determining the sexual fitness of a male, for usually only the victor will copulate afterwards.” I understand that this combat is performed when a female is nearby.

I have seen similar behavior with rattlesnakes, but instead of remaining on the ground, the ones I saw were intertwined vertically for almost half their length.

The female will lay up to 24 eggs, in the summer, which hatch in the fall.

Gopher snakes use communal dens for winter hibernation.

If you see a gopher snake in your yard, let it be. It may do you the service of eating your pack rats, then move on.

A version of this article first appeared in the Arizona Daily Independent.

See also:

Clever Horned Lizard

Metachromatic spiny lizards


Speckled Rattlesnakes

Venomous Lizards

Saguaro National Park and Climate Change

On Saturday, Oct. 2, 2010, the National Park Service hosted a symposium at the Arizona-Sonora Desert Museum which considered “How might climate change affect Saguaro National Park.”

The keynote speaker for the morning session was Dr. Jonathan Overpeck from the University of Arizona, a lead author for the IPCC, and one of the scientists mentioned peripherally in the “climategate” emails. He spent a few minutes addressing that.

Overpeck said that the southwest was “ground zero” for climate change. He showed a graph of global temperatures from 1880 to present. I’ve seen him use that graph before. This is a case of cherry-picking to enhance a point. He starts the graph just as the planet began to warm from the “little ice age” so yes, the apparent temperature rise can be depicted as dramatic, especially if one expands the vertical scale of the graph. If, however, he had begun the graph 1,000 years ago during the Medieval Warm Period, the recent rise would have been seen for what it is, just part of the natural cycles.

Overpeck predicted that as temperatures rise, the southwest would become drier because the jet-stream which brings us winter rains will move north and its storms will move north with it. (The summer rains will have little change because they are drawn from the south.) Perhaps that will happen, and the year 2010 is an anomaly with an unusually high winter rainfall. My rain gauge recorded twice as much rain this past winter as I got during the summer monsoon.

Overpeck repeated several times that he has high confidence that human carbon dioxide emissions are responsible for the global warming we are experiencing. In the Q&A after the talk, I asked him to cite some specific physical evidence that human carbon dioxide emissions have produced significant warming. During his answer he said that climate models work best when carbon dioxide is added in, but that’s not evidence. He also made what I thought was an extraordinary statement. He said that most climate scientists (of his group) believe that carbon dioxide is responsible for global warming “because they can’t think of anything else” that would cause such warming. That too, is not evidence. In other words, a lead author of the IPCC climate studies cannot cite any physical evidence that human carbon dioxide emissions have a significant effect on global temperature. Rather, it must be so because they think it so.

Three talks dealt with saguaro populations. These studies are conducted on specific, small plots within the National Park; some were established as long ago as 1935. Each plot is periodically visited and saguaros are counted and measured. The assumption is that these plots are representative of the population as a whole, however, each plot may represent only a micro-climate, not the whole, and may be subject to special local conditions. For instance, in one plot, pack rats were eating the saguaros. The saguaro population is cyclic and depends on, among other things, the amount of precipitation, the number and severity of days of frost, and the health of palo verde trees which act as nurse plants to young saguaros. Some plots showed increases in the number of saguaros while others showed decreases. The National Park Service performs a saguaro census every ten years. Among the plots they studied there was a general increase in saguaro population over the last ten years. For more information on the NPS monitoring program, see See more details from Tony Davis’ article in the Arizona Daily Star.

Dr. Donald Miles of Ohio State University reported on lizard populations. His study involved study plots similar to those in the saguaro studies. Since lizards are ectothermic, rising temperatures may limit their hunting time since the lizards cannot be outside if it is too hot. Miles reported that certain lizards have become “extinct” from some study plots and predicted that 66% of species will become extinct in 40 years. He did mention that his extinction models have not been calibrated with actual extinctions. When pressed during Q&A, Miles admitted that the “extinction” really meant that the lizards were not observed in the test plots and that they simply could have moved to better climes.

Dr. Phil Rosen studied reptiles along transects in Organ Pipe National Monument. He found no significant lizard decline, but did find decreased populations of snakes (except for sidewinders).

Kris Ratzlaff, a University of Arizona graduate student, studied lowland leopard frogs and canyon tree frogs in the Rincon Mountains. Her study provides baseline data for future investigations. She found that almost all leopard frogs in the three drainages studied were infected with the chytrid fungus, a problem for frogs world-wide. There was much less infection among the tree frogs.

Dr. Travis Huxman gave the keynote talk of the afternoon session. Huxman is a University of Arizona biology professor and director of Biosphere 2. He noted that rising atmospheric carbon dioxide makes plants more productive and more drought tolerant. The magnitude of this aerial fertilization effect is tempered by the type of plant (fast growing vs. slow growing) and by the amount of water available.

Much of the symposium was about speculative problems. There is, however, one real and current problem that has little to do with climate change: the invasion of exotic grasses such as buffelgrass.

Native grasses are generally confined to higher elevations and cannot survive on the hot desert floor. However, non-native species imported for cattle feed, highway beautification, and landscaping, can survive on the desert floor, and that is the problem. “Buffelgrass grows densely and crowds out native plants of similar size. Competition for water can weaken and kill larger desert plants. Dense roots and ground shading prevent germination of seeds. It appears that buffelgrass can kill most native plants by these means alone.” The other problem is that these exotic grasses fill in the space between native plants and thereby can transmit wild fires.

The take-away from this symposium is that the issues are complex. While we would all like some definitive answers, real science is messy.

For more information on droughts, see my article “Drought in the West.”


There are 17 species or subspecies of rattlesnakes in Arizona and they all object to being stepped on. So watch where you walk. In my field experience as a geologist, I’ve encountered many rattlesnakes (26 on one morning), and most of the time they don’t rattle. They prefer to remain inconspicuous. See here for a list of all recognized rattlesnake species and subspecies.


Some herpetologists regard rattlesnakes as one of the most highly specialized animals on the planet. The venom, a toxic saliva, is a complex mixture of enzymes that include hemotoxins, that attack the blood and start the digestion process in tissue, and anticoagulants. The Mohave rattlesnake also carries neurotoxic venom that may cause circulatory arrest or respiratory paralysis. That said, however, fewer than 1% of people bitten in the U.S. die as a result of the bite, but many sustain tissue damage. About 20% of defensive bites are dry – no venom injected. Venom is injected via curved fangs which fold back into the snake’s mouth. Rattlesnakes seem to have spare parts to replace damaged fangs. Baby rattlesnakes are venomous and ready to go, they just can’t inject as much venom as a larger snake.

If you are bitten, the University of Arizona College of Pharmacy recommends that you get to a hospital to get antivenom and treatment for tissue damage. Don’t bring the snake; the antivenom treats all bites. Also don’t use tourniquets, that just concentrates the venom and produces more tissue damage. Don’t use ice for the same reason. Don’t cut and suck; you can’t get enough venom out to make a difference, and, if a friend does it for you, he takes a chance of envenomating himself. Do remove tight clothing, shoes, jewelry from the affected limb.

Rattlesnakes are pit vipers, which means they have heat-sensing organs located between their eyes and nose. A rattlesnake can detect the heat of a candle at 30 feet. Some researchers claim that a rattlesnake can perceive a temperature difference of as little as 0.01 degree Fahrenheit at one foot. The snakes use this heat-sensing ability in several ways. They can follow the heat trail of prey even in total darkness. They can tell if an animal is too large to be prey and thereby avoid it. And, the exothermic (cold-blooded) snake can use their temperature sensor to help find places to properly regulate body temperature.

Rattlesnakes are most active in the warmer times of year, but in Arizona, they may be out and about any time the temperature is between 70 and 90 degrees F.

Rattlesnakes are born live, rather than hatch from eggs. The babies have the first segment of the rattle, but can’t make a noise until it sheds and gets another bead on its rattle. Mother rattlesnakes care for their young at least until after the first shed. It is a myth that you can tell the age of a snake by counting the beads on the rattle. Beads are added at each shed, and the snake may shed several times a year. The rattle material is keratin, the same as your fingernails. There isn’t anything inside the rattles; the noise comes from the segments bumping against each other as the snake vibrates its tail up to 60 times per second.

Rattlesnake eyes have slit pupils like cat eyes. The gopher snake, a non-venomous constrictor, is often mistaken for a rattlesnake, but it has round pupils and lacks the triangular head of the rattlesnake.

Other snake myths. Snakes cannot dislocate their jaws. They can open their mouths very wide because they have two jaw joints on each side separated by a (quadrate) bone. Snakes also lack bony chins. Each half of the lower jaw is separated by cartilage which enables the snake to move the lower jaws independently.

Rodents are the main prey of the rattlesnake, so the snakes provide a valuable service. They also take birds, lizards, and baby rabbits and squirrels.

At the Arizona-Sonora Desert Museum, the staff capture an average of 100 rattlesnakes per year on the grounds. After capture, the snakes are marked by color-coding the tails and, more recently, by inserting a radio chip to allow tracking. The snakes are released on the far reaches of the grounds. Rattlesnakes, however, are very territorial, so many return. So, if you are at the Museum and see a rattlesnake with a multi-colored tail, you will know that particular snake is a return visitor. And no human visitors have ever been bitten by a rattlesnake at the Museum.