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Gila Monster

Family: Helodermatidae

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Heloderma suspectum Photo © Animal-World: Courtesy David Brough

  The Gila Monster is a patriotic lizard, beautifully colored and the largest lizard native to the United States!

   The amazing Gila Monsters are quite unique among the reptiles. They have stunning patterns to their scales. Set on a black background are vibrantly colored designs in reds or yellows, depending on the specimen.

   The Gila Monster is one of two species of venomous lizards in the family Helodermatidae. Both Species are similar in both appearance and habits, but Its venomous cousin, the Mexican Beaded Lizard Heloderma horridum, is slightly larger and darker.

   No other lizards have been have been so immersed in myth and mystery as these two. Possibly because of their rather secretive lifestyles, staying in burrows a good deal of the time; as well as being the sole survivors of an ancient group of lizards, the Monstersauria. They have been two of the least understood and least studied of the lizard species.

   Gila monsters do not make good “pets”. But for a serious herp enthusiast, their habits and environment requirements make them ideally suited for captivity and visual enjoyment. Despite their size, they don't require a lot of area for activity, and they are relatively easy to keep.

   Being venomous, the Gila Monster can be a bit tricky to handle. But their eagerness to eat readily-available food items and their sheer beauty are more than enough to make any intermediate to experienced herp keeper fascinated.

   Both species of Heloderma are sluggish in habit, but they have a strong, tenacious bite...with a 'bulldog' attitude of not wanting to readily let go.

For more Information on keeping Lizards see:
Guide to a Happy, Healthy Herptile

Description:
   The Gila Monster has beautiful patterns to their scales. These lizards always have a black background, but their patterns can occur in red or yellow, depending upon the specimen.

• The reticulate species Heloderma s. suspectum, are mottled and blotched like the one pictured above. They are found primarily in the Sonoran and Chihuahuan deserts.
• The banded species Heloderma s. cinctum, found primarily in the Mojave Desert, has broad double crossbands when they mature.

   These are large lizards, with adults reaching about 21” to 22” (53 - 56 cm) in length and weighing about three to five pounds. They have a long life span, living for up to around 20 to 30 years of age.
   Gila Monsters have long stout bodies with short wide spread legs, a swollen looking tail, and curved claws good for digging. They have a majestic head and a forked tongue, reminding one of a snake. Their beadlike skin has scales that are rounded and raised. The thick tail contains energy stores for the colder months, and unlike many of the lizard species, their tail will not separate from their body. Though generally rather sluggish looking, they are surprisingly athletic looking when in a hunting stance.
   They closely resemble the Mexican Beaded Lizard in many ways. The venom glands are in their lower jaws, and the venom leeches out from the glands and flows through the grooves in the teeth of the lower jaw and is delivered by a chewing motion. These lizards use venom primarily as a defensive weapon.
   Sexing in Gila Monsters is extremely difficult, though methods using ultra sounds have proven to be relatively accurate. There is little to no sure method of visually sexing them.

Care and Feeding:
   Gila Monsters are more than easy to feed and care for. They have a low metabolism and thus have a feeding schedule similar to that of a young snake. They are fond of many commercially available foods, such as mice and rats. Gilas will, unfortunately, eat just about anything placed in front of them.
   While eggs are a natural food source for these lizards in the wild, feeding of eggs in captivity can lead to obesity. Obesity is a large risk in Gila Monsters. In the wild, their food supply for an entire year would be consumed in three to four months.
   Adult males and nonbreeding females can be fed about every two weeks. In preparation for the breeding season, females can be fed up to twice a week, as the conversion from fat to yolk takes the stored food from the tail to produce the eggs.
   Water should be provided in a large, un-tippable bowl. Gila Monsters will spend quite a bit of time soaking in their water bowl and it needs to be large and stable enough to support them. If they are allowed to soak for long periods of time daily, the water bowl will need daily cleaning.
   Spot cleaning should be performed on a daily basis, or at least following meals. Any liquid spills should be cleaned up immediately, with the damp litter being removed. All of the substrate should be replaced every one to two months, depending on age and how often the feedings are.

Environment:
   Adult Gila monsters should be maintained with a minimum of 3 ½ square feet of floor space. As they spend most of their time in the wild in a den, they don’t require a huge amount of space. The cage should be big enough to provide a good thermal gradient, a warm basking spot at one end of the enclosure to a cooler location at the opposing end.
   Possible substrates include newspaper and wood shavings. Aspen shaving work well and are also affordable. These allow for spot cleaning, or cleaning where you see defecation. All of the bedding should be replaced periodically and any wet bedding needs to be removed immediately.
   A den or hide should be provided for the Gila with enough room for them to move around inside. This can be built up using many of the lightweight reptile rocks, which will prevent harm to the animal if they fall. This should be provided at the cool end of the enclosure. To prevent any possible escape of these venomous lizards, a screen lid is highly recommended.

Temperature and Lighting requirements:
  The temperature needs to be between 85 - 90° F (29 - 32° C) degrees under the basking light, measured from the substrate of the cage. The cool end of the cage needs to be in the low seventies, at the same level of measurement. A basking area can be as simple as an elevated rock and placed under the basking light.

Social Behavior/Activities:
   In the wild, Gila Monsters have a solitary nature. They can be kept with success in groups, given enough room, but many keepers prefer to keep them in solitary enclosures to better replicate the natural environment. Some male competition for females has been noted in the wild, and in captivity the losing male cannot retreat.

Handling:
   When you need to handle your Gila Monster, a thick pair of gloves should always be worn. No matter how experienced the handler is, or how tame the Gila is, they are still a venomous animal and a simple scare is all it could take to provoke a bite. Gilas should always be handled with great care and with a minimum of distractions.

NOTE: If you are bitten by a Gila monster, seek medical attention immediately and call the Poison Control center if necessary.

Breeding/Reproduction:
   Gilas are very hard to sex, making captive breeding extremely difficult. A procedure has been developed using ultrasounds to sex the animals. This causes no internal harm to the animal and is relatively accurate.
   In the wild, the male would scent out the female in the late spring. This translates to introducing the male and female to one another in the first week of April. Copulation is generally seen by the middle of April. Females can be rotated through the cage of a single male and bred more than once during the season to raise chances of fertile eggs. Copulation has been seen from lasting 15 minutes to two and a half hours.
   Gravid females need to be kept separately. Keeping them with other Gilas can cause the female additional stress and result in destroyed or eaten eggs. Timing between mating and deposition of eggs (oviposition) is between 42 and 55 days. Gilas can lay between 2 and 31 eggs.
   When the female starts to dig around the cage, she should be provided with a nest box. Sphagnum moss is a good substrate to use in the box where she lays her eggs. Vermiculite can be used as an incubation medium, keeping the temperature at about 79° F (26° C). Incubation temperature has been known to vary from 79 to 85° F (26 - 29° C), though temperatures above 85° F (29° C) degrees are believed to be a cause of failures to hatch. The eggs are relatively difficult to hatch, as they need high relative humidity but very low actual exposure to water. Incubation lasts around four and a half months.
   Hatchlings should be allowed to exit the egg on their own; do not attempt to aid a hatchling! When left to their own devices, it can take up to four days for a baby Gila to leave its egg from the time they pop open the first hole. There is a good amount of yolk still in the egg and this is their first vital meal. After this, they may not eat for a few days to a week, but it is nothing to be concerned about. Pinkie mice are a good food to offer to the hatchlings.

Ailments:
   The biggest problem with Gila monsters is obesity, due to their extremely low metabolism. Young Gila monsters will grow rather quickly, but upon reaching maturity, they will often eat to the point of obesity. Take good care to only feed as much as is necessary.

Availability:
   Gila Monsters can be purchased for a variety of prices, depending upon the pattern you are looking for. Banded Gila Monsters go for about $1,600 – $2,000, while Reticulated Gila Monsters go for $1,200.

   ** Before attempting to find a breeder or other source for your Gila monster, you need to check the laws of both your state and your city. For example, in Colorado, there are no laws saying that you must have a permit to own a Gila monster, however, in Colorado Springs, it is illegal to own a Gila monster without a permit. This could be due to its good tourist trade and the risks of a poisonous lizard rampaging around the city. Still, it would be best to check the regulations in your area.

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Latest Comments
Gila monsters are a protected species under Arizona state law in the United States, and may not be killed, or kept in captivity without a license. They are listed as a threatened species under the United States Federal Endangered Species Act, as well as in Mexico. It is against Arizona State law to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect this animal or any attempt to engage in such conduct. I just saw one wandering around outside my house the other day. jay 2007-05-16

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Author: Monica Rearick.
Additional Information: Clarice Brough, CRS
Edited by Animal-World.