2022 Gila monster season: Engage!

Winnie the monochromatic (axanthic) Gila monster wasn’t quite ready for the 2022 breeding season despite being six years old but we look forward to her joining the group in 2023.

Our 2022 Gila monster breeding season is about to kick into high gear. Our group (or lounge of Gilas as it’s known) of adults will be coming out of brumation soon and the captive breeding season begins. But all’s not been quite as our monsters sleep here at Goatsby’s Place, quite to the contrary as we’ve worked hard to prepare for this season and improve on what we’ve learned over the past year’s successes and failures.

Our 2020 holdbacks aren’t ready to breed so do not get brumated during the winter until they are a few years old.

Our primary goal this year (other than to have fun and raise amazing baby Gila monsters!) to increase our hatch rate to 80% or better. Over the past few seasons are hatch rate has been 50% or less which is disappointing to say the least but I have some ideas as to why our success has been limited. This year will be the first time we can test these theories and prove them out. Last year‘s phorid fly attack and the fact that only one male was cooled certainly contributed to the lack of success. This year on the other hand we have equal ratio adult pairs and are working with our own ultrasound to closely follow the inner workings of the male and female reproductive systems.

Ultrasounding a very patient Gila monster. Photo by J. Brueggen

On a technological front we are migrating to a fully web-based system to monitor and adjust things as the season progresses. We’ve purchased and implemented the über-cool Spyder Robotics Herpstat SpyderWeb proportional thermostats to control the heat, and importantly, set up a nighttime temperature drop for the Gilas. We continue to use the SensorPush system to monitor ambient temperature and relative humidity, and added night vision cameras to monitor copulation and activity between paired Gilas. Having all this work with Alexa is just a geeky bonus, but fun nonetheless.

Herpstat 2 SpyderWeb proportional thermostat is a web-based unit that can be checked and adjusted from anywhere!

And last but certainly not least, keep an eye out on our YouTube channel as we begin a series of videos documenting the full reproductive season of our Gila monsters, from pairing, to copulation, to egg-laying and incubation, and if all goes well, hatching. My goal is to produce informative and fun videos to help increase our understanding of the amazing Gila monster. The good news is you get to see lots of beautiful Gila monsters, the bad news is you’ll get to see my ugly face from time to time:)

2021 baby Gila monsters!

The last three Gilas hatch!

The 2021 baby Gila monsters are all out and settling in here at Goatsby’s Place! We are very proud of our beautiful baby monsters, and feel blessed to have been successful again this year. While most are spoken for, we may have a few available for new homes. Please email us if interested, or to get on the list for 2022.

Anything can happen on Halloween

Trick or treat! Baby Gila monster emerging from its egg.

I have always loved Halloween, but for the past two years our Gila monsters have been hatching on this magical day which delights me too no small end. HAPPY HALLOWEEN!

For those who know, know. Thank you, Tim Curry.

PIT tagging Gila monsters

Caption reads, “OUCH Dad!!”

PIT (passive integrated transponder) microchip tags are certainly not new to the pet industry, being used extensively on cats and dogs to help lost animals find their way home. Taking this application a step further, some reptile owners PIT tag their herps to help keep track of animals in their collection or to identify those produced by a certain breeder. Until recently I haven’t given much thought to putting these microchips into my Gilas but a recent incident convinced me otherwise.

Someone on an Internet forum claimed to be selling one of my Gilas, but they didn’t have the “Certificate of Captive Birth“ that I provide with each Gila born here, and the person selling the animal was not registered on my list. I take this very seriously as there are folks selling wild-caught animals as captive-bred using well known breeders names and credentials. After a short investigation, it was found that the Gila was not one of mine but someone was using my name to sell a Gila of unknown origin (I cannot say for sure if it was wild-caught, but the circumstances around this sale were very suspicious). To help verify my Gilas in the future, I decided to look into PIT tagging my lizards.

After doing some research and speaking with my friend John who is very knowledgeable in both Gilas and PIT tags, it seemed this would be a good way to go in ensuring my Gilas could be easily identified within my group and to those that purchase from me.

Overall, the procedure is simple and can be done at home with the help of an experienced vet tech or if you are lucky enough to have a good friend knowledgeable in such things (thanks John!), otherwise inquire with your herp vet about the procedure. The health and safety of the animal is always paramount so please don’t take shortcuts on this or any matter concerning your Gilas. I was able to do this at home because I had an experienced friend but would not hesitate to take my Gila monsters to the vet to get the PIT tag installed safely.

After installing the PIT tag, it was checked with a scanner to be sure it didn’t come out.
Handling Gilas is always a risky proposition, be sure to put the safety of yourself and those working with you first!

Better together

With the discovery that hatchling Gila monsters over winter in their nest, I wanted to perform my own non-scientific social study of hatchling Gilas. Normally baby Gila monsters are reared on their own in solitary containers to facilitate easier feeding and maintenance, but this year I housed two siblings to see how they would be together. While they were housed alone for for the first two months to ensure both were feeding regularly and healthy, they were introduced into an adult-sized terrarium and have been there ever since. So far? The photo above best describes the behavior from the hatchlings. The definitely tend to share the same “burrow” / hide more often than not, and are active at the same time. Feeding has to be done carefully so as to ensure there is not fighting over food.

I do not know if there is a certain age they go their own way, but I will keep they together through the first year to see how they act with each other. Seeing this and the behavior of my adults makes me wonder about the social structure of these reptiles. There truly is still so much to learn about Gila monsters!

Check here for the scientific findings from the discovery above.

May 2021 Update: Nest boxes and hopefully eggs soon!

Momma getting ready for the big day!

Though work and the other parts of my life have kept me from updating this blog on a regular basis, working with the Gilas has not slowed down. As of today my females are gravid and have gone through their pre egg-laying shed so oviposition is expected within the next week, according to my calculations.

Two of my females cages with privacy tint installed.

This year my nesting protocol has changed due to the failures (or, opportunities for learning) of last year. last year one of my females delayed egg laying by about 10 days which resulted in the death of six viable eggs. Not a very fun lesson but certainly an opportunity for improvement. I think last year the female did not have the proper secure nesting area and held her eggs until she could not hold them any longer. I also tried a new nesting material which did not work out very well as it did not hold moisture for very long. This year, things have changed.

To help increase privacy and to solve the humidity issue everything has been changed. To start, the entire cage has been converted to a nest box. This is to allow the females to continue to thermoregulate (though over lower temperatures) throughout this period. I have installed privacy tint on 1/2 of the cage as well as a large black hiding box to increase privacy. I also went back to good old sphagnum moss misted daily to help maintain moisture in the cage. The ultimate goal is to provide a secure area that matches conditions for positive egg growth. So far it appears to be working as the conditions in the cage mirror those in my incubator (see below screenshot from my SensorPush app).

Pretty close!

Will this ultimately work? We will know within two weeks. If all goes well my females will lay viable eggs this year. If not, I’m sure there will be a lesson learned and opportunity for improvement next year! Fingers crossed!

Great Gila article on Slate.com

I always look for all things Gila on the internet and come across this fun and well-written article on Slate.com of all places. Enjoy!

Don’t Call It a Monster

But be very cautious around the venomous, determined, lumbering Gila monster.


Constance CaseyApril 26, 20138:00 AM

We’re the ones with language, so we have the power to call one of our fellow vertebrates a monster. As lizards go, the Gila monster is unusually clunky, chunky, and large—not a lissome tropical creature like a gecko or chameleon. It’s not pretty, and it is venomous, a trait that inevitably complicates any relationship. Still, loathing the creature is irrational; being careful around it is not.

North America’s largest lizard gets the first part of its name from the Gila River, which runs through Arizona and New Mexico. Its habitat is the desert scrub and dry foothills of the Sonoran, Chihuahuan, and Mojave deserts. The creature is the subject of dozens of dread-inducing bits of folklore that are, at best, unverifiable. (Unlucky male camper in the desert wakes up to find a Gila monster chewing on some tender body part. Lizard spits venom in someone’s eye. Lizard springs several feet in the air to attack. Parachutist lands on lizard. Lizard’s foul breath can kill you.)

The creature’s lumbering form and sinister look play a part in popular culture. In The Treasure of Sierra Madre, for example, a Gila monster is part of a suspenseful ordeal for the character played by Humphrey Bogart. In Meet Me at the Morgue, a 1953 mystery by Ross MacDonald (a writer as good as Raymond Chandler), a sullen blonde says of her suitor, “Big offers he makes. Mink coat, a new car, a trip to Honolulu. I told him I’d sooner go with a Gila monster.” As part of the 1950s trend for enlarging animals to make them scarier, the creature is the subject of a 1959 B movie, The Giant Gila Monster. First victims? Necking teenagers.

Herpetologists, bless them, find the 2-foot-long, lumbering lizard fascinating and beautiful. Its body has bands of black alternating with the colors of an Arizona sunset –pink, buff, or orange. They hope that more knowledge will lead to less detestation, perhaps grudging respect. (One unexpected Gila monster fact is that a research scientist at a Bronx Veterans Affairs hospital found in the 1990s that something in Gila monster venom lowers plasma glucose to normal range in people with Type 2 diabetes. A synthesized version is now an ingredient in the widely used diabetes drug Byetta.)

Though the Gila monster is shy, and you should consider yourself lucky if you see one in the desert, there is certainly reason to be careful in its presence. Its bite is extremely painful, though very rarely fatal. Of the 5,000 or so known lizard species, the Gila monster (Heloderma suspectum) is among the few that are venomous. Another is its neighbor to the south, the Mexican beaded lizard (Heloderma horridum). (Note: “Beaded lizard” is a much better, less prejudicial choice for a name than “monster.” In both The Treasure of the Sierra Madreand The Giant Gila Monster, the lizard shown in the films is called a Gila monster but is actually a Mexican beaded lizard.) A few years ago, Australian researchers proposed that Indonesia’s infamous Komodo dragon could also deliver venom. (It was previously believed the dragon’s mouth was so full of muck that the victim died of a bacterial infection.)

The lizard’s species name comes from the Greek helos for stud, as in the head of a nail, derma for skin. The suspectum because the man who named it—paleontologist E.D. Cope, in 1869—at first only suspected that the lizard was venomous. It took another half-century to confirm it. With their studs they’re well armored, but a determined coyote can still rip one apart, and free-ranging cats often kill immature Gila monsters. A Gila monster can live up to 28 years; the most common cause of death, as more of the desert is paved, is being run over by a car. With a nonautomotive predator, the lizard’s first line of defense is to retreat. If cornered, it exhibits a repertoire of warning signals, including hissing and opening its mouth wide.

The nail-head look comes from osteoderms, bony beads embedded in the skin. Jan Johnson, an Arizona-Sonora Desert Museum curator who cares for 20 Gila monsters, says their hide feels like an exaggerated basketball. An X-ray shows, in addition to the usual spine and leg bones, an array of polka dots.

Careless handling, which Johnson does not engage in, is the usual cause of bites. The vast majority of verifiable recorded bites (about 150 in the past 60 years) are on the finger or hand, delivered by a pet whose apparent passivity lulled its owner into handling the creature, or by a wild Gila monster avoiding capture. (Collecting Gila monsters in the wild is against the law.) Some of the bites occurred during a demonstration in a classroom or lecture, which has to have been deeply embarrassing as well as painful. Inebriation is often involved. There’s a verified story of a man in a bar bitten while playing a kind of Russian roulette by reptile, repeatedly sticking a finger into the animal’s mouth.

The last recorded fatality was in Casa Grande, Ariz., in 1930. As reported in the Arizona Republic, “Tom Reap, 62 years old, proprietor of the Moore pool hall, died at 12:20 o’clock this noon in the Casa Grande hospital, two hours after he had been bitten by a Gila monster.” The story continues with useful information about what not to do with a venomous lizard. “Mr. Reap was playing with the animal in the pool hall when he was bitten. The animal had been brought into the hall by one of the patrons and several were standing around looking it over and discussing it when Mr. Reap appeared. He began tapping it on the nose, witnesses said, and upon being cautioned replied: `Oh, it wouldn’t hurt you even if it did bite.’ ”

Reportedly it took a helpful pool hall patron five minutes, using a pair of pliers, to detach the lizard from Mr. Reap.

Which brings us to the Gila monster’s venom delivery mode. The creature is loath to use its ultimate weapon, but once deployed the system is absolutely terrifying. The Gila monster is the pit bull of reptiles. Its short, sturdy skull with blunt, black snout is adapted to a long bite. (The shape works; it hasn’t changed much in the past 23 million years.) Venomous snakes by contrast have fragile skulls, built to conform to the shape of whatever they’re eating, often something bigger than they are. Snake venom is injected, hypodermic-style, through fangs in the front of the mouth, and it acts quickly. The point is to subdue prey before its thrashing injures the snake.

If you are so astoundingly foolish or unfortunate as to be bitten by a Gila monster, it will get a good grip and then chew; it can hold on for as long as 15 minutes. The grinding releases venom from glands into grooves in its sharply tipped teeth. (All venom, incidentally, is modified saliva.) Oddly and inefficiently, the two glands are located near the bottom teeth, and the poison must travel upward, presumably by capillary action.

The longer the bite, the more venom enters the victim’s body, via lacerations made by the teeth. One emergency medicine handbook provides “tips and tricks” for removing the animal. These include the following: Don’t pull or pry it off; that increases the possibility of leaving teeth in the wound. A flame under the jaw or immersion in water may work.

In addition, there’s this rather considerate advice: “Put the animal’s feet on the ground so it doesn’t fear falling.” And a particularly ominous note: “Always take special care to prevent reattachment of the animal to the victim or subsequent attachment to the person removing the animal.” Doctors are advised when cleaning the wound to make sure all the teeth are removed.

The effect of the venom, potent but not as damaging as a rattlesnake’s, is excruciating pain that has been described as a steady burning, like a spine embedded in the flesh, lasting up to 24 hours. There’s no commercially available antivenin; doctors treat pain and swelling and the most dangerous possible effect, a drastic lowering of blood pressure.

Gila monsters use their venom sparingly and primarily as defense against predators rather than to subdue prey. (Their fellows in using venom primarily for defense are the platypus and the stonefish.) Daniel D. Beck, author of Biology of Gila Monsters and Beaded Lizards, says he has often seen Gila monsters “delicately swallow” young cottontails without the chewing or pumping that’s displayed when they envenomate an enemy. The lizards’ favored foods are bird and reptile eggs, newborn small mammals, and bird nestlings—food sources that do not put up much of a fight. Eggs seem to be their favorite; the lizard splits the egg and, kittenlike, laps up the yolk. A Gila monster can eat one-third of its body mass at one sitting and survive on three good meals a year.

Because they don’t go out foraging often and they stay in a cool place in the summer, you’d be fortunate to see a Gila monster in the wild, Beck says. “You’d have to be a fool to be bitten,” says Beck, who has not suffered a bite. A Gila monster spends 95 percent of its time in a burrow, out of the sun, venturing out mostly in spring to find food and a mate.

Like everything that lives, Gila monsters are driven by hunger, fear, and the need to reproduce. What looks sinister and snakelike—the forked tongue flicking out every few seconds—is the lizard’s way of experiencing the world. The Gila monster is essentially tasting the air, picking up clues as to where there might be some quail eggs to eat, a likely mate, or a coyote to avoid. When the lizard’s tongue pulls back in, the two tips are inserted into little holes in the roof of the mouth. This delivers the captured odor particles to the Jacobson’s organ, named for 19th-century Danish anatomist Ludvig Levin Jacobson. Some of the chemical compounds bind to receptor molecules, sending messages to the lizard’s brain. Other reptiles have the Jacobson’s organ, as do some amphibians and mammals.

The Gila monster evolved such a keen sense of smell because food in an arid environment is widely distributed. The creature rarely runs, but it can trudge for miles. Most people’s impression of Gila monsters, from seeing overfed specimens in a zoo, is that they’re obese and lethargic. Smaller lizard species, in contrast, are in danger of being eaten and adapted by being well camouflaged or very fast. (And there’s their amazing ability to drop the tail when threatened. The severed tail continues to twitch, keeping a predator’s attention.)

The Gila monster does not give up its tail, which is as useful a camel’s hump for fat and water storage. In times of scarcity, the tail shrinks down to something like a ballpoint pen rather than the usual kielbasa sausage.

Low metabolism and frugal energy use are advantages in food-scarce regions. But recently it has been found that though they have a low metabolic rate, Gila monsters possess high aerobic capacity and surprising endurance.

Beck demonstrated this by putting a Gila monster on a rubber treadmill with a Dixie cup over its head. A tube from the cup sends the lizard’s exhalations to a gas analyzer and calculates the rate of oxygen consumption. How does a Gila monster respond to this gymlike activity? Some object, Beck says, but most keep on tramping “in a kind of trance. Into the Zen of being a lizard.”

In the wild, Beck tracks the lizards’ long routes by radio transmitters implanted surgically (with difficulty because of the studded skin). He and other scientists have found, by using radio telemetry, that a lizard is loyal to a couple of particular shelters. Sensibly, they find a south-facing haven in winter, one that’s cooler and moister in the summer.

Beck loves them, but when asked what a Gila monster’s life is like he has to say “dull.” They do spend most of their time doing nothing. However, from April to June, there is drama, ritual combat that’s a challenging endurance test. Two males meet in what is essentially a wrestling match, arching and flexing sumo-fashion. The contest, which can go on for hours, ends when one has forced his opponent to the ground and remains on top. Though equipped with venom and sharp claws, the males, sensibly, do not kill or wound each other. The loser walks away unscathed; the winner, having proved his fitness to reproduce, gets breeding territory or, better, a shelter with a female inside.

When a female has been won, the victorious male lies beside her and rubs his chin on her back and neck. If she accepts him, she raises her tail and the male moves his tail under hers, bringing their vents into contact. Copulation lasts from half an hour to an hour. Which brings us to the hemipenis. Like snakes and other lizards, a male Gila monster has a retractable penis that pops out like the finger of an inflatable glove, an advantage on rocky soil. Actually, he has two; they pop out together but only one at a time is used. The hemipenises are elongated tubular structures stored in the tail, decorated with tubercles in a fashion Beck calls “flounced ornamentation.”

In July or August, the female lays one to 12 eggs in an underground hole. Incubation may last nearly 10 months, and the 4-inch-long young may not emerge until a year after insemination.

For millions of years, human beings figured very little in Gila monsters’ quiet lizard lives. Then we began building deep into the desert. One of Beck’s formerly prime locations for studying Gila monsters is St. George, Utah, now the site of a fast-growing retirement community. (Someone in one of those newly built units probably has a bottle of Byetta in the medicine cabinet.) Desert houses, surrounded by irrigated land, provide attractively moist, shady environments for the bolder lizards, which is beginning to create a problem. Every year dozens of Gila monsters (and thousands of rattlesnakes) are removed from properties in Phoenix and Tucson. From the homeowner’s point of view, the lizard is large and scary—and protected by state law; killing it is not a legal option. From the herpetologists’ point of view, there are too many Gila monsters run over by cars and too little unpaved, unspoiled desert habitat left for them.

Beck, who grew up exploring deserts in his native Utah, allows that the Gila monster doesn’t seem beautiful to most people, “But they’re an indication that we live in a beautiful place. Lose them and the beauty is diminished.”