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.
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.
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).
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!
It’s mid-February, the adult Gilas are slowly coming out of hibernation, the 2020 babies are going to new homes, and to say we are excited about the 2021 season is an understatement! This year we have an ultrasound that will help us improve breeding and oviposition, and we will share some information on this here once we can successfully figure it out:$ If you are interested in getting on the list for 2021 or just want to discuss monster, drop us a message!
In case you haven’t seen them, here are 2020’s babies!
My 2020 Gila monster season is off and running. After reviewing my data and re-reading my Gila books, I was going to wait until after April 1 this year to pair the Gilas as that is when the magic happened (and seems to be for others as well). With the Shelter-in-Place order in full effect I got bored and but them together last weekend, and guess what? No activity yet. What I have found interesting is that the Gilas seem to remember each other from last year and there was no fighting between the pairs (females bit males for being too pushy). This year they are much more chill, and are spending time together the hide boxes. I have been checking in at night to see what is going on and while both Gilas are active, copulation has not yet been observed. Being a Nervous Nelly, I am concerned that they will not breed this year but will hold my real worry for late April
To me, the real question is could Gila monsters mate for life? I’ve read that in the wild males go back to the same shelters where they have previously copulated and in my observations females certainly do prefer some males over others. The way they rest together and spend time with each other makes this is an interesting avenue to explore. Some breeders swap different females in male cages and have great success, but I am going to try leaving known pairs together to see how things go. I can see why having one pair of Gilas could be difficult to breed and that groups (3.3 or greater) are suggested.
As with all things, time will tell. New observations, and hopefully some activity, will be reported here. Stay tuned..
Earlier this year adidas in collaboration with famed basketball player James Harden released Vol. 4 of his namesake shoe. Why is sneaker news on a Gila monster website? Because a variant of the shoes are Gila monster pattern! And they are quite a match with our beloved venomous lizard’s intricate pattern. Previously, a Vol. 1 shoe was also called Gila monster pattern but they were similar colors and not patterned the same so not of real interest to me. But when these cam out, I knew a pair had to be mine! I haven’t played basketball in decades, but maybe I can wear them the Gila room to blend in a bit better:) Get yours here from adidas while you can, they seem to sell out fast!
With the babies I’ve held back are growing like weeds and coloring up beautifully, I’ve taken the adults out of brumation and am warming them up and will be feeding them their first meal soon. I’m both excited and nervous as to how this season will turn out. Will all the eggs paid be fertile? Will all the fertile eggs go to term? An educated guess says no to both but if improvements are made I am moving in the right direction.
I’ll be doing some new things this year. First, I’ll be pairing straight reticulated with reticulated, and banded with banded. Also, instead of leaving switching males between cages I will keep one male with one female for the duration of the breeding season. The females do seem to have preferences, and hopefully they still lie each other this year. I am waiting until the last week of March to start pairing as last year the females were not receptive and often attacked and bit the unrelenting males so it would be nice to avoid this drama and potential injury. I’ll keep everyone posted on the progress and of any successes and failures on my second year of breeding these amazing Gila monsters!
So, almost after all hope was lost on Day 153 the first Gila monster egg pipped from its leathery shell! Egg 02 at first cut a small slit and then a few more and over the next two days began to emerge from the egg. At first the baby Gila stuck its nose out, then it’s head, then half its body, and finally the entire body. It appears that hatching is a labor-intensive process as there are long pauses between progressive stages and also seems to be a good way of ensuring all the contents of the egg are consumed before leaving the egg. Over the ensuing days this process was (and currently is for two more lizards) repeated over and over, with Gilas emerging from their shell about two or so full days from pip to full emergence. Once the contents are completely devoured the neonate Gila monster leaves its shell and begins to wander the egg box. I witnessed one Gila that was out actually eating the egg yolk of another just coming out of its shell! Greedy bastard.
Once fully emerged and climbing around, the little monsters are pulled from the egg box, photographed, weighed, and set up solo in an 18 quart Sterelite box with paper towels as bedding and small water dish. The paper towel bedding serves as a clean substrate while the umbilical wound heals and the first few meals are eaten and passed through to make sure everything is going well. I will attempt the first feeding next week after the yolk has been fully digested and look forward to raising the babies from there!
I will be posting updates on the neonates growth, as well as some thoughts and insights on my first season captive breeding Gila monsters. Some reviews of the equipment I used is also likely in order as these items played an important role in my success. Whew, what an amazing season! The process has been fun, though frustrating and worrisome at times, and I look forward to greater success next year with these amazing reptiles!
I started collecting Harmony Kingdom boxes in the mid-90’s after discovering them at a collectibles shop in the mall. They were mostly animal and my first box was, of course, a reptile (chameleons). For those that don’t know, Harmony Kingdom is a collectible series of themed boxes and figurines crafted by artisans in the United Kingdom. What caught my eye was the attention to detail and thoughtfulness put into the designs, with a nice dose of cheeky British humor. Though my collecting has slowed down over the years, I was very into it for some time and in an almost obligatory move mailed the company requesting a Gila monster box. Not saying that my letter reached the highest echelons of Harmony Kingdom or that it was even read, but in late 2009 the company released two versions of our favorite venomous lizard (you’re welcome).
Tip the Scales was carved by Master Carver Peter Calvesbert, hand-painted by local artisans in the Cotswold region of England, and comes in two versions. V1 is a normal colored Gila monster limited to 300 pieces, while Tip the Scales V2 is more of a bone-colored Gila and limited to 100 pieces worldwide! Very low numbers for the typical run for Treasure Jests and quite collectible.
These boxes are a must-have for any Gila monster enthusiast. The detail on these boxes is amazing, especially considering their diminutive size. The osteoderms look real as do the proportions of the body and look of the lizard. Besides the great detail and the beauty of these boxes, there are a some cool Easter eggs for us enthusiasts. Here is what the card that comes with the boxes say: “The Gila monster is a venomous lizard native to the southwestern U.S. and northern Mexico. Not only did Peter painstakingly sculpt its reticulated pattern, but he included numerous secrets. Its Latin name, Heloderma suspectum, means studded skin. Suspectum derives from palaeontologist Edward Drinker Cope’s suspicion that the lizard may be poisonous due to its teeth grooves. Gila refers to the Gila River Basin in Arizona, where these lizards were once plentiful. Exenatide is a drug used in the treatment of diabetes and is a synthetic version of a hormone found in the saliva of the Gila monster. Open the lid of this fixed edition box figurine to find a baby hatching Gila and Peter’s initials under one of the rocks.” The tent cards (cards that come inside the boxes and to be set up for retail display) can be downloaded from the Harmony Kingdom website here: V1V2
The boxes pop up on eBay from time to time, and I have even seen one languishing in a store that needed rescue! So, have some fun and look for one or both of these amazing Harmony Kingdom Gila monster boxes, you will not be disappointed!!
Fans of the fantastic website Heloderma.net already know how knowledgeable and passionate Dr. Schwandt is about Gila monsters, and in September 2019 he released his long-awaited book on our favorite subject. Being the Gila geek I am, my order was placed the day pre-orders were announced and was certainly not disappointed when it arrived. The book covers a wide range of topics in detail and covers some information not previously seen in other books. Certainly a must-have for your collection of Heloderma reading, the book can be purchased from the author on his website or here.
The Yahoo! Heloderma group created and maintained by Mark Miller is being taken down. So, I thought it would be a shame to let Mark’s work fade into oblivion and have posted his well-curated Heloderma Bibliography here for posterity. One of these days I will update this list with some of the newer books that have come out since it was compiled.
CREATED by Mark Miller / UPDATED circa 1998 by Mark Miller
Allen, Morrow J. 1933. Report on a collection of Amphibians and reptiles from Sonora, Mexico, with the description of a new lizard. Occas. Papers Mus. Zool. Univ. Michigan, no. 259, pp.1-15
Arnberger, L. P. 1948. Gila monster swallows quail eggs whole. Herpetologica, vol. 4, pp. 209-210
Beddard, Frank E. 1906. On the vascular system of Heloderma, with notes on that of the monitors and crocodiles. Proc. Zool. Soc. London 1906:601-625, 8 fig.
Bloyd, Gary R. 1970. The gila monster (Heloderma suspectum). Bull. Florissant Herpetol. Soc. (8):1-2.
Bogert, Charles M., and Rafael Martin del Campo. 1952. Geoclines and ontoclines in lizards of the genus Heloderma. Annu. Meet. Amer. Soc. Ichthyol. Herpetol. 32nd., Austin, Texas.
Bogert, Charles M., and Rafael Martin del Campo. 1956. The Gila Monster and its allies: the relationships, habits, and behavior of the lizards of the Family Helodermatidae. Bull. Amer. Mus. Natur. Hist. 109:1-238, 35 fig., 20 pl., 5 tab., 2 Maps.
Boulenger, Georges Albert. 1891. The anatomy of Heloderma. Nature (London) 44:444.
Boulenger, Georges Albert. 1891. Notes on the osteology of Heloderma horridum and H. suspectum, with remarks on the systematics position of the Helodermatidae and on the Vertebrae of the Lacertilia. Proc. Zool. Soc. London 1891:109-118.
Boulenger, Georges Albert. 1918. Les lezards Helodermatides de l’Eocene Superieur de la France. Comp. Rend. Acad. Sci. (Paris) D 166:889-893.
Cheek, L.W. Watch Out! The Little Monsters Bite. Arizona Highways 1990 Vol. 88 (8): 42-46
Cooper, Robert H. 1969. Melanoma in Heloderma suspectum Cope. Proc. Indiana Acad. Sci. 78:466-467.
Cuesta Terron, Carlos. 1934. El escorpion. Heloderma horridum Wiegmann. 2a Ed. revisada por Rafel Martin del Campo. pp. 1-14. Folletos Divulgacion Client., Inst. Biol., Univ. Nac. Mexico.
Curtis, L. 1949. Notes on the eggs of Heloderma horridum. Herpetologica 5(6):148.
Dolensek, E.P., Cook, R.A. Clinical Challenge [Radiographs of enteritis due to Salmonella infection in a Gila monster (Heloderma s. suspectum)]. J Zoo Animal Medicine 1987. 18 (4): 168-170
Durham, Floyd E. 1951. Observations on a captive Gila Monster. Amer. Midland Nat., vol. 45, pp. 460-470, 1 table.
Edwards, H. T., and D. B. Dill. 1935. Properties of reptilian blood. II. The gila monster (Heloderma suspectum Cope). J. Cell Comp. Physiol. 6(1):21-35, 5 fig., 5 tab.
Funk, Richard S. 1966. Notes about Heloderma suspectum along the western extremity of its range. Herpetologica 22(4):254-258.
Grasse, Pierre-P. 1970. Les glandes venimeuses et le venin des sauriens helodermatides, p. 676-680, fig. 454, In, Pierre-P. Grasse, Traite de zoologie, anatomie, systematique, biologie, vol. 14. Reptiles, Fasc 2, Caracteres generaux et anatomie. Masson et Cie Ed., Paris.
Haddon, E.P. 1954. Little monster. Outdoor Life, vol. 114, pp. 46-49, 15 illus.
Hensley, M. Max 1949. Mammal diet of Heloderma. Herpetologica, vol. 5, p.152
Kauffeld, Carl F. 1943. Field notes on some Arizona reptiles and amphibians. Amer. Midland Nat., vol. 29, pp.342-359, 4 illus.
King, F. Willis 1932. Herpetological records and notes from the vicinity of Tucson, Arizona, July/August 1930. Copeia, pp.175-177.
Komori, K; Nikai, T; Sugihara, H. Purification and characterization of a lethal toxin from the venom of Heloderma horridum horridum. 1988. Biochem. and Biophysical Research Communications. Vol 154 (2): 613-619
Koster, William J. 1951. The distribution of the Gila monster in New Mexico. Herpetologica, vol. 7, pp.97-101, map.
Mebs, Dietrich. 1968. Some studies on the biochemistry of the venom gland of Heloderma horridum. Toxicon 5(3):225-226, 1 fig.
Mebs, Dietrich. 1969. Isolation and properties of kallikrein from the venom of the gila monster (Heloderma suspectum). Hoppe-Seyler’s Z. Physiol. Chem. 350:821-826, 3 fig., 2 tab. (Germ., Engl. summ.).
Mebs, Dietrich. 1969. Purification and properties of a kinin liberating enzyme from the venom of Heloderma suspectum. Naunyn-Schmiedebergs Arch. Pharmakol. Exp. Pathol. 264(3):280. (Germ.).
Mebs, Dietrich. 1970. Biochemistry of Heloderma venom. Toxicon 8(2):142-143 (abstr.).
Mebs, Dietrich. 1970. Biochemistry of kinin-releasing enzymes in the venom of the viper Bitis gabonica and of the lizard Heloderma suspectum, pp. 107-116, 6 fig., 2 tab., In, F. Sicuteri, M. Rocha e Silva and Nathan Back (Eds.), Bradykinin and related kinins: cardiovascular, biochemical and neural actions. Plenum Press, New York.
Mebs, Dietrich. 1970. Untersuchungen ueber die wirksamkeit einiger schlangengift-seren gegenueber Heloderma-gift. Salamandra 6(3-4):135-136 (Engl. summ.).
Mebs, Dietrich, and H. W. Raudonat. 1967. Biochemie des giftes der krustenechsen Heloderma suspectum und Heloderma horridum. Naturwissenschaften 54(18):494.
Mebs, Dietrich, and H. W. Raudonat. 1968. Biochemical investigations on Heloderma venom. Mem. Inst. Butantan 33(3):907-911, 4 fig.
Michl, H. 1972. (Review of) Untersuchungen ueber die wirksamkeit einiger schlangengift-seren gegenueber Heloderma-gift, by Dietrich Mebs, 1970. Toxicon 10(2):189.
Patterson, Robert A., and In Soon Lee. 1969. Effects of Heloderma suspectum venom on blood coagulation. Toxicon 7(4):321-324, 4 tab.
Pregill, G.K.;Gauthier, J.A.;Greene, H.W. 1986 The Evolution of Helodermatid Squamates with Description of a New Taxon and an Overview of Varanoidea (Trans. San Diego Soc. Nat. Hist 21 (11): 167-292
Shaw, Charles E. 1968. Reproduction of the gila monster (Heloderma suspectum) at the San Diego Zoo. Zool. Garten 35(1-2):1-6, 3 fig.
Shufeldt, R. W. 1890. Contributions to the study of Heloderma suspectum. Proc. Zool. Soc. London 1890:148-244, 3 pl.
Stahnke, Herbert L. 1950. the food of the Gila monster. Herpetologica, vol.6, pp.103-106.
Strel’nikov, L.D. 1944. Snachenie solnechnoi radiatsii v ekologii vysokgornyh reptilii. [Importance of solar radiation in the ecology of high mountain reptiles.] Zool Zhur., Moscow, vol. 23, pp. 250-257.
Taub, Aaron M. 1963. On the longevity and fecundity of Heloderma horridum horridum. Herpetologica 19:149.
Trutnau, Ludwig. 1968. Gefangenschafts-beobachtungen an krustenechsen (Heloderma suspectum Cope). Aquarien Terrarien Z. 21(4):120-125, 10 fig.
Trutnau, Ludwig. 1970. Ein beitrag zur behandlung erkrankter krustenechsen (Heloderma horridum und Heloderma suspectum). Aquarien Terrarien Z. 23(8):251-253, photos.
Trutnau, Ludwig. 1970. Die skorpion-krustenechse Heloderma horridum (Wiegmann). Aquarien Terrarien Z. 17(7):228-231, 5 fig.
Tu, Anthony T., and David S. Murdock. 1967. Protein nature and some enzymatic properties of the lizard Heloderma suspectum suspectum (Gila monster) venom. Comp. Biochem. Physiol. 22(2):389-396, 6 fig., 1 tab.
Tu, Anthony T., and David S. Murdock. 1967. Protein nature of Gila monster (Heloderma suspectum suspectum) venom. Int. Congr. Biochem. 7th., Tokyo (abstr.).
Van Denburgh, John. 1922. Helodermatidae in Reptiles of Western North America… Vol. 1: 470-476, plt 44-47. SF Acad. Sciences
Vandermeeers, Andre; et al. Chemical, immunological and biological properties of peptides like vasoactive-intestional-peptide and peptide-histidine-isoleucinamide extracted from the venom of two lizards (Heloderma horridum and Heloderma suspectum) Eur. J. Biochem. 164, 321-327 (1987).
Vorhies, Charles T. 1917. Heloderma suspectum, automobile tourists and animal distribution. Science, vol. 68, pp. 182-183
Wagner, Ernie; Smith, R.;Slavens, F. 1976. Breeding the Gila monster in captivity. International Zoo Yearbook, Vol. 16