Dinner in Cloud Break, Arizona

Today I received an e-mail describing a tale of mortal combat between a lizard and snake in Cloud Break, Arizona. The text of the e-mail reads, "These pics were taken by one of the road crew at Cloud break, Arizona last week. It took a total of 5 hours for the King Snake to finish off the Goanna. (Sand Monitor) As you can see, they put some signage up so it couldn't be run over."


What really happened though, is that a creative but lazy jokester has taken a series of pictures of a lizard and a snake from Australia and changed the location specified in the accompanying text, perhaps to scare their neighbors. I'm going to guess they're from, oh..I don't know...Cloud Break, Arizona? I can't actually find information about this town, does it really exist?


Our first clue is the mention of a goanna, which do not occur in North America. You may recall Paul Hogan eating one in Crocodile Dundee (although he didn't like the taste). Maybe whoever altered the e-mail didn't know this. But, at least they were aware that Black-headed Pythons can't be found in Arizona, so they changed the species to a Kingsnake, which do occur in Arizona and look superficially similar to the python in the picture.

Black-headed Pythons can reach about eight feet long, much bigger than Common Kingsnakes can; their large size makes them well equipped to eat large lizards such as goannas. Kingsnakes also like to eat other reptiles, although none as large as the goanna in the picture.

If you're interested in learning about what snakes can really be found in Arizona, check out this site. Information about Arizona's lizards can be found here.

Give Me a Home Where the Blue Gopher Snakes Roam

It was Monday morning and Tropical Storm Ida was welcoming us to the new week. As the early chills of fall enveloped us, dark clouds gathered in the distance, ominously blocking out the sun. Perhaps seeing the look of concern on my face, Dirk Stevenson consoled me,

“No worries, the indigos won’t mind.”

Dirk is the Director for Inventory and Monitoring for Project Orianne, a large non-profit organization dedicated to conserving the eastern indigo snake where they remain and restoring populations to areas where they have disappeared. Dirk was to be my field companion for the day, accompanying me to my field site in the Florida panhandle. He hoped to establish whether indigo snakes, often locally known as gopher snakes, still persisted in the area, despite the lack of a confirmed sighting in over ten years.

Indigo snakes once roamed throughout the southern half of Georgia through Florida and west to Mississippi. Today, however, they may be found only in isolated and relatively undisturbed areas and they’re thought to have disappeared entirely from both Mississippi and Alabama. Although one of the largest snakes in North America (they can reach over eight feet long) and a fierce predator (including of rattlesnakes), the species is surprisingly vulnerable to changes to its habitat. As a large animal, it requires a large area to survive. An indigo snake living near humans is vulnerable to being killed on roads or by domestic animals. Its docile nature made it a popular target of collectors who wanted to make pets of the giant beasts.

Perhaps the most insidious threat to the continued persistence of the indigo snake in the southeast relates to the population decline of another species altogether, the gopher tortoise. Gopher tortoises are considered keystone species, meaning their presence influences many other organisms in their shared habitat. Tortoise burrows are used by a wide variety of other animals, notably the indigo snake. Indigo snakes use these burrows as shelter during very high or low temperatures and may search through them to find potential prey. They may be used for nesting, for mating, or to fight rivals. In some areas where they can both be found, tortoise burrows are an integral component of the landscape for indigo snakes.

Tortoises have declined for a number of reasons; historically they were harvested intensively by hungry humans. But that this practice has been outlawed doesn’t mean tortoises are in the clear. They prefer pine forests with few trees, an open canopy allows a lot of sun to reach the ground and encourages growth of the plants they like to eat. To keep pine forests open, however, requires fires to burn through every couple of years, as they did in the past after lightning strikes. These fires keep hardwood trees from becoming established in the forest, when they would otherwise crowd out pine trees and block out the sun. Many southeastern forests haven’t been exposed to fire in a long time, making the habitat unsuitable for gopher tortoises, which reduces the amount of refuges available for indigo snakes.

When it comes to indigo snakes, the Florida panhandle is a head-scratcher. Although the number of gopher tortoises in the area is considerably lower than elsewhere, they are still hanging on. And in this region can be found some of the most expansive longleaf pine forests remaining in the world. It would seem as if the area was tailor-made for a healthy population of indigo snakes, yet it’s been a decade since they were last spotted.

As we drove to the first site, a secluded area where you can still find a small number of tortoise burrows if you know where to look, Dirk explained the unusual behavior of the indigo snake. In the fall, on days when most other snakes would be holed up for warmth, male indigo snakes are conducting serious business; that is, looking for females. These males will crawl throughout the forest searching for either other snakes or the tortoise burrows they might be hiding within. It was our hope we might encounter one of these giant serpents as it undertook one of these excursions or perhaps a female coiled up and basking in the sun outside a burrow.

I couldn’t help but hope we found an indigo snake, a species that has successfully eluded me so far. I knew it was a tall order to see a federally threatened animal in an area where they haven’t been found in a decade, but I would’ve settled for seeing a large track in the loose sand leading down to a tortoise burrow.

This would indicate to us that an indigo had traveled through recently and give us some reason to be optimistic for the species’ recovery in the region. If they were still clinging on, the site might be considered a suitable spot to introduce more snakes, in the hope they would interbreed and thrive.

In short order, Ida started threatening us again, now with the beginnings of the rain that would drench the region throughout the night. Despite the less than ideal conditions, we dutifully visited sites we thought held the most potential, walking through the woods looking for the disturbed soil that might indicate a tortoise burrow. We were disappointed though, to find that even in areas where you could find dense populations of tortoises only years ago, they were few and far between now. Without burrows to serve as targets for our search, finding an indigo snake was like finding a needle in a haystack, if they were even there at all.



Indigo snake and indigo snake trail pictures appear here courtesy of Dirk Stevenson. The gopher tortoise picture appears here courtesy of Sean Sterrett.

A 55 foot boa in China?

Check out what is now being claimed as a 55 foot boa from China.

It should be noted that Chinese officials are claiming this photo is clearly a hoax, as boas are not native to Asia. Well, they're right...kind of. It's true that boas do not typically occur in Asia, they are limited to North and South America (with some exceptions), while pythons are found in Africa, Asia, and Australia. But the thing is...that's not a boa in the picture, it is a python. You can tell by its distinctive patterning.

Boas and pythons differ in other ways too. Boas give birth to live young while pythons lay eggs. Also, pythons have heat sensing pits in their face and boas do not.

So, why is it a hoax? Because no snakes alive today get that large. Even the giant reticulated pythons and green anacondas, our planet's biggest snakes, struggle to reach 30 feet.

Why does it look so huge? Well, if you've already read this post, you know exactly why.

Are Bites from Baby Venomous Snakes More Dangerous Than Those From Adults?

For all the fear and hatred they evoke, snakes inspire fascination like no other group of animals. Those that kill snakes on sight will eagerly take every opportunity to share stories of their encounters with serpents. Animal lovers will hold court with tales of large snakes they have seen and those they hope to find. And perhaps most interestingly, rational-minded people, even those that spend much of their time outdoors, will often believe the most far-fetched ideas about snake biology.

When it is revealed that I am a researcher that specializes in reptiles, I am often confronted by curious individuals wanting to know the veracity of a particular legend. I’ll never forget the woman who earnestly asked me whether I knew what kind of snake would grow into separate, fully-functioning individuals when it was cut into pieces with a garden hoe. I believe I noted that I wasn’t familiar with that species.

They say that every myth has some basis in reality, so it shouldn’t be surprising that there are some legends that seem more reasonable. Perhaps the question that I am posed most often relates to the relative danger of young versus adult rattlesnakes.

The legend goes that young snakes have not yet learned how to control the amount of venom they inject. They are therefore more dangerous than adult snakes, which will restrict the amount of venom that accompanies a bite. It’s repeated so often that it’s become a sort of mantra among laypeople and biologists alike.

It seems like a simple enough suggestion, but to examine this topic requires some examination of the assumptions implicit within the framing of the question as well as delving into some hot topics in biology. There are four main assumptions when the question is framed in this manner: 1) snakes are able to control the amount of venom they inject, 2) there is some disadvantage to a snake when it injects all of its venom in every bite (otherwise why not inject all of their venom all of the time?), 3) as a result, a snake will learn of these disadvantages and change its behavior as it matures, and finally, 4) a full envenomation from a young snake is more dangerous than a partial envenomation from an adult snake.


First things first, can a snake control the amount of venom they inject? This is actually a contentious issue among snake specialists. There are some who believe snakes do indeed control the amount of venom they inject, they are proponents of what is considered the Venom Metering Hypothesis (among scientists, a hypothesis is a preliminary explanation of observed phenomena; these explanations haven’t been rigorously tested. This is a step below a scientific theory, which is a conclusion based on observations and experimentation). Past studies have indicated snakes inject different amounts of venom in different situations, but the trends are sometimes inconsistent.

A recent review of studies on the subject suggested although some researchers have documented trends in venom injection, there isn’t compelling evidence to suggest that it was necessarily controlled via any decision by the snake. They came to this conclusion because the trends didn’t seem to indicate the amount of venom the snakes injected would have any consistent benefit in the wild. And if there was no apparent benefit in the wild, then why would snakes be choosing to exhibit this behavior?

An alternative hypothesis has been termed the Pressure Balance Hypothesis, which suggests the amount of venom a snake injects is due to a combination of snake anatomy and the properties of the object the snake is biting. This would explain why snakes tended to inject different amounts of venom into different targets with no clear benefit to the serpent.

For the purpose of this discussion, let’s say that snakes can control the amount of venom they inject. The second assumption states there must be some disadvantage to a snake injecting all of its venom when it bites; otherwise, a snake would just inject everything every time. Why not?

This is another interesting question. It may be beneficial for a snake to keep some venom on hand in case its intended prey requires a second dose, or if a first prey item escapes and another quickly appears. Another scenario is that a snake does not want to inject all of their venom into their food just in case they are suddenly confronted by a potential predator of their own. Finally, it takes some time for a snake to produce more venom, and energy that goes into venom production is energy these animals could use for other important tasks, such as growth or reproduction. Consequently, common sense would suggest that there are some disadvantages to a full release of venom at every opportunity. It may be possible to confirm this suggestion via experimentation by testing whether snakes that frequently inject all of their venom experience slower growth, lower reproductive rates, or high mortality. To determine this would require a complex study, one that has not yet been attempted.


The third assumption states that as a snake matures, they learn there are disadvantages to delivering full venom loads during every bite and as a result, they change their behavior. For learning to occur, there must be positive or negative reinforcement. If we state that a snake may keep venom on hand in case a prey item (or one that appears shortly after the first prey item) requires a second bite, this snake must have experienced a number of incidents where they injected a fraction of the venom they had into a prey item only to have this prey item escape. Over time, they may learn that it’s beneficial to keep some venom for a successful attack later. This may make sense superficially, but one might think that it would be more likely that the snake learns to inject more venom with their first bite and increase the chance of a fatality than saving venom just in case they experience another opportunity to bite their intended food again.

If we state that a snake learns to withhold venom from their bites in case a potential predator quickly appears and attempts to eat them, a snake must have learned that it’s somehow beneficial to do so. This snake would have had to experience numerous predation attempts and survive to know the costs associated with their venom injection behavior. If an “empty” snake were to be eaten by an owl or bobcat, then it would know that it should’ve kept some venom (but it’s too late to do anything about it because it’s dead). For a snake to learn it’s beneficial to keep venom ready, it would have had to survive an attack, and if it survived an attack without any venom left over from a previous feeding attempt, then I guess it didn’t really need that venom anyway. So, by logically extending the third assumption, we find that it’s difficult to envision a scenario that would enable a snake to eventually learn that it’s beneficial to withhold the amount of venom it injects with their bite. Remember, it would likely require that this scenario happen numerous times for a snake to eventually learn the consequences of their behavior.

It’s possible that there are evolutionary advantages to a snake retaining some venom in case it’s needed in a defense against an attack by a predator. It’s easy to conceive how snakes that tended to have venom on hand would be more likely to survive longer and produce young. If this behavior had a genetic component, the surviving snakes would pass on the tendency to conserve venom to their offspring. This is not learning however, and the behavior would be innate (i.e. something they’re born with) or instinctual.

Finally, the fourth assumption states that a bite from a young snake that has no control over the amount of venom it injects is more dangerous than a learned adult. But, there are some big snakes out there, and just a fraction of their total venom capacity could be more than 100% of a young snake’s potential venom output. So, I don’t think this final assumption is always valid.

To summarize, although it’s possible that this legend is true and baby snakes are more dangerous than adults because they haven’t learned to control the amount of venom they inject when they bite, it’s safe to say this is unlikely to be the case. Due to the complexities of the original question, I doubt this statement will ever be tackled in a manner that sufficiently addresses all of its assumptions. But until then, try not to get bitten by any venomous snakes, no matter how old they are.

Gopher Tortoises of Alabama

Having recently returned from this year's annual meeting of The Gopher Tortoise Council, I'm inspired to reprint a brief article about gopher tortoises I wrote for the Alabama Coastal Foundation's newsletter. Laura Wewerka of the GTC and Wally Smith of Alabama PARC and Alabama's second-most distinguished university provided input:

Gopher tortoises, Gopherus polyphemus, are perhaps one of the most recognizable animals found in Alabama. Plodding around the southeastern United States from South Carolina down through Louisiana, this shelled reptile can be found in Alabama south of the Fall Line.

They’re the only tortoise native to the southeastern United States, and adults can be distinguished from the box turtle, another terrestrial turtle, by their large size and gray un-patterned shell. Hatchlings and young tortoises typically have square brown markings encircling a yellow center on their carapace (top shell); these markings tend to fade with age.

The presence of tortoises is most often detected first by stumbling upon their characteristic burrows, shaped like half-moons. These animals spend most of their life underground in these holes, which they dig with their extremely strong front limbs. But they’re not the only ones who benefit from their frequent tunneling. Dozens, if not hundreds, of different species of insects, amphibians, reptiles, mammals, and even birds may find refuge within tortoise burrows. Some animals, like rabbits and ground-dwelling sparrows, may hide in tortoise holes when fire burns through an area. Others, like the federally threatened eastern indigo snake, spend their winters residing with the dark recesses of the tortoise lairs. When tortoises are removed from a forest, this may have serious implications for the remaining species that rely on their burrows for shelter.

Gopher tortoises are closely associated with longleaf pine forests, and the ranges of the two overlap across the country almost precisely. Tortoises like these savanna-like forests because a lot of light reaches the ground; this light encourages plant growth which provides food for the tortoise. This is why it’s so important to manage longleaf pine forests with periodic prescribed burning; the fire helps limit invasion of hardwood trees that would shade the area and eventually crowd out the pine trees. Tortoises living in a longleaf pine forest that isn’t managed with frequent fire will eventually try to disperse to more suitable areas or find refuge in sub-par habitats with more light streaming in, such as powerline corridors. Recent research, in fact, has suggested that the reintroduction of periodic burning has an incredibly beneficial effect on gopher tortoise densities when fire has been historically suppressed in an area.

Unfortunately, just as the longleaf pine forests have shrunk in size due to development and mismanagement, tortoise populations have declined as well. Perhaps the decline of the tortoise is linked most closely to the vanishing longleaf pine ecosystem, but they face other threats too, including collisions with cars, poaching for food, and disease. Without conservation efforts aimed at protecting tortoises and their habitat, they have a bleak future. Fortunately, there are some encouraging trends: Alabama recently outlawed the practice of gassing tortoise burrows. This irresponsible and environmentally destructive practice was undertaken to drive out rattlesnakes, which could then be either killed immediately or brought to rattlesnake roundups, where the snakes are killed later. Tortoise tended to stick around in their burrows after they were gassed, exposing the animals to lung damage and eventual death. Recent laws banning this technique, in concert with land conservation and proper forest management, may help ensure that future generations can look forward to encountering the gopher tortoise in Alabama.

You are what you eat

What does an animal eat? It’s perhaps the most basic question a biologist can ask. Knowing what a species consumes is critical to understanding to how relates to its habitat and the ecosystem. Sometimes, these secrets are readily revealed.

Many snakes, when disturbed, will be all too happy to divulge their last meal by presenting you with a fresh regurgitation of partially-digested creature. Maybe these snakes feel they will be able to flee more rapidly with an empty stomach. On the other hand, perhaps this encourages potential predators to find something else to eat, something that smells a little more appetizing.

Snakes are famous for constricting their prey, I’m sure many people have nightmares of a large specimen wrapped around them. But, lots of snakes in our area don’t constrict at all, they simply grab prey in their mouth and start swallowing. Their bottom jaw is made of two different bones which they manipulate to swallow large prey and work it down their throat. As you may imagine, this is likely an unpleasant experience for the hapless prey, which, as they’ve not been constricted, are swallowed alive.

On these occasions, a frightened snake could mean good news for its last meal. Hognose snakes are famous for their defensive displays, which often includes throwing up. They are also fearsome toad hunters, these amphibians are their primary prey. It is not unusual to find a bloated hognose snake that will freely cough up a live toad with only the slightest provocation. This toad, perhaps after a flustered moment, will eagerly take the opportunity to hop away, and perhaps will be more cautious the next time a serpentine shape approaches. I recently worked in a lab in southwest Georgia that kept a toad as a pet for years after a recently captured hognose snake gave him a second chance at life. A hognose snake I recently captured coughed up a live spadefoot toad that weighed more than it did!


Snakes don’t always make it that easy for you, however, and traditional methods of determining snake diet don’t present very appealing options. Typically, when a researcher finds a snake with a tell-tale bulge in its body, the snake can be coerced into regurgitating its prey by pressing a thumb against its body and working the prey item out of its mouth. In the best case scenario, the researcher now has a recently ingested prey item that allows for easy identification. What is more likely, however, is that an odorous warm glop will appear, a glop that defies classification. In both cases, the snake loses its meal. For an animal that doesn’t eat often, a forced regurgitation may have unintended consequences to its long-term health.

But, it’s better than the other typical method. If you were to peruse some classic snake ecology papers, you’ll quickly realize that thousands of snakes have given their lives so that we can better understand their natural history. One of my goals is to advance our understanding of snakes without sacrificing them in the process. If you’ve watched any of the number of crime shows on television, you know that researchers can often find DNA from the most unusual sources. Although the methods are often dramatized on the television, some of the concepts are grounded in real science.

You are what you eat, right? When I catch a snake, I hold it in a cage until it provides a scat sample and I preserve this scat sample in alcohol or acetone. The goal is to take these samples into the lab and subject them to a long and complicated process with the goal of extracting any present DNA. These small fragments of DNA are then exposed to other strands of DNA in the hopes of kickstarting their replication. Different species have different and unique strands of DNA; these strands are made of base pairs (if I mentioned adenine, thymine, cytosine, and guanine, does it bring you back to your high school biology class?). When the DNA has replicated, we can examine the unique sequence of base pairs in the product and determine what unlucky species had been eaten by the snake.


It’s expensive, time-consuming, and requires additional testing before it’s accepted as a legitimate methodology, but I hope this technique changes the way we study and learn about snakes. Ideally, it will be more accurate than sorting through a glop of vomit, less intrusive than forced regurgitation, and no snakes will be killed in the process.


Sometimes snakes make it easy for you. Here's a recently captured hognose snake that coughed up a partially digested frog. There was enough left to identify it as a southern leopard frog. Photo courtesy of Michelle Baragona.

Big Snake in Newark, Delaware

Each morning I get sent recent articles pertaining to snakes, turtles, and similar creatures in the news. Some reflect just how detached we've become from the flora and fauna that surround us.

Although this blog generally pertains to southeastern wildlife, I can't resist commenting on an article I received about a giant snake on the loose in Newark, Delaware. On Friday afternoon, a couple kids took a picture of a large snake crawling in a tree near their house. Later they told their mom that they had seen a "black snake", this is one of the common names generally used for the Eastern Rat Snake (formerly Black Rat Snake), Pantherophis alleghaniensis. Here in the southeast, we have a closely related species, the Gray Rat Snake, Pantherophis spiloides.

In any case, that should have been the end of it.

The mother, amazed at how large the snake looked in the pictures, proclaimed that this could be no native snake. Local officials "confirmed" that this was likely an escaped python or boa constrictor, perhaps 8-10 feet long. Neighbors were warned of the potentially dangerous animals roaming their streets and backyards and were encouraged to keep their children and pets under close supervision.

The kids were correct. This is not an exotic snake. This is not a dangerous animal. What they saw was a rat snake. Granted, a large individual can surely be a shock to the system as it's true that some can reach in excess of eight feet. This makes them one of the largest snakes native to North America, but they are harmless, unless you're a squirrel or rat.

Rat snakes have well-developed climbing abilities and are often found crawling through tree branches in search of birds or a secluded place to rest. Given that fall is advancing, it's possible that this snake was looking for somewhere safe to spend the winter, or maybe a final meal before it commences hibernation. These snakes can be common in suitable conditions, but not necessarily frequently encountered. This may explain the odd behavior exhibited by the adults involved in its identification and subsequent warnings. I'll grant them that it may not be easy to identify the snake from the one available picture given that only its underbelly is visible, but a quick internet search reveals important clues.

For some reason, many are inclined to exaggerate the size and associated danger of our native snakes. The provided article, and the embedded quotations, are no exception. I suspect they only encourage others to kill snakes because they fear their safety and well-being are in jeopardy, when nothing could be further from the truth.

A large Gray Rat Snake captured in southwestern Georgia

Update: The newspaper in question has published a correction to their story. Within this correction, a Delaware biologist identifies the snake as a rat snake. But then, states that only experts can identify snakes. Do you think this is true, considering the initial reaction of the 13-year old who initially spotted the animal?