Gila Monster Facts | Anatomy, Diet, Habitat, Reproduction

The Gila monster (Heloderma suspectum) is a bulky slow-moving lizard of the southwestern United States and northwestern Mexico. It is a venomous lizard species that has inspired wildlife-lovers for centuries. Gila monster is the larget lizard of the United States. Although people have heard much of Gila monsters yet only a few are lucky enough to see one in the wild habitat.

Gila Monster Facts


  • Gila monsters are rather hideous creatures that one can immediately recognize in the first place. The monster’s head reminds us of a large rattlesnake except that it is nearly all black.
  • The eyes shine like a diamond especially when the animal goes mad. They are almost entirely black or dark brown
  • They have pale rose body with some spots or patterns along the way. Gila monsters have bluish pink mouth from inside as that of an alligator.
  • It has an elongated body and flattened head; along with the short neck and sturdy legs.
  • Gila monsters have sharp hearing sense and fairly good sight during the day. It can also sense any vibration that is caused by the intruder. Monsters feel vibrations on the ground. One of the reasons might be that they are extremely slow travelers.
  • Like big cats, Gila monster has sharp claws that are extendable at will.
  • The snout is entirely black and so as its feet. The skin has brown or black patterns that often reflect on orange shade. Sometimes the color is cream or yellow. All these markings are unique to each individual.
  • Monster’s tail always makes up 50% of the entire body length.
  • Like dinosaurs, Gila monsters have armor-like skin in the form of rounded scales that protects the animal from being vulnerable to any cut or puncture. Scales cover the head, body, legs, back, and even sides of monster.
  • Adult males and females seem to have same color and markings so much so that it is hard to distinguish between the two. However males are quite bigger and have wider head or body as compared to females.
  • Biologists believe that the black or orange shade may warn predators that the monster is venomous. However not all predators are sharp in recognizing the nature Gila monster.
  • Predators of Gila monster include coyotes, hawks, skunks, mountain lions, foxes, badgers, and bobcats.
gila monster facts
Gila Monster flicking its tongue to pick up the chemical odor ©


  • Arizona is home to thousands of Gila monsters where they make habitats near paloverde trees and saguaro cactus as well as on the Sonoran Desert.
  • Most of the habitats are found in the mountain ranges and foothills near the towns of Gila Bend, Ajo, Wickenburg, Wikieup, Safford, Superior, and Florence. They like to make homes on desert lands. The largest concentration of monsters can be found in The Papago (Tohono O’Odham) Indian reservation.
  • In the southeast Arizona, monsters make habitats on the grasslands. However they do not typically build habitats in the dry mountains such as the Grand Canyon National Park.
  • In Utah, they are found in habitats with an elevation below 3,200 feet in the Mohave Desert. In here Gila monsters are widely distributed.
  • They have isolated population in southern Nevada particularly in southern Lincoln county and Clark County.
  • Gila monsters make dens that may be as deep as 5 feet beneath the ground.


  • Gila monsters are most likely to build habitats in boulders, rocky, and rough land as these are the ideal habitats for winter hibernation. They will also seek shelter in natural crevices or under rocks.
  • They are thought to use the same hibernaculum the next year. Besides, monsters also share it with rattlesnakes and desert tortoises.
  • Monster’s habitats include shrubbery and desert trees as well as triangle-leaf bursage, jojoba, hackberry bushes, velvet mesquite trees, and paloverde trees.
  • They also prefer to live in Dry washes or arroyos, mesquite thickets or bosques. These habitats are home to a large number of cottontail rabbits and nesting birds.


  • Unlike iguanas, Gila monsters are extremely slow movers and they are thought to stay at the same place for several hours. Sometimes it gives a look of a dead animal.
  • While moving on land, Gila monsters lift the belly and tail above the ground.
  • If it is unable to escape, the monster may roll back into the rock and hold the ground firmly producing a hissing sound to warn off predators.
  • Gila monsters move at a speed of 0.15 miles per hour or 13 feet a minute. In short bursts, they can cruise to about 1.5 miles per hour.
  • When it comes to attacking the enemy monsters may spin around with the lightning speed.
  • They have solid armor-like skin that can only be cut with the strongest of teeth.
  • Gila monsters are the only lizards that may engage in activities for longer periods of time. That is to say they have got the maximum stamina.
  • Thanks to the powerful claws, monsters are expert diggers. They usually use forefeet to take out the sand while striking continuously with left and right hands.
  • Not only that they dig their own burrows but also Gila monsters can expand or enlarge the already-built natural crevice.
  • Gila monsters are highly territorial animals.
  • They will rarely search bird’s nests that are in the shrubs, cholla cactus or even in trees.
  • They are not very good swimmers but are nevertheless consistent because of their long lasting stamina.
  • Gila monsters are less likely to tolerate heat. They are mostly most active during the temperatures 67 – 99 degrees Fahrenheit.
  • During the hot days of summer Gila monsters stay in the burrows underground and will only come out once the temperature cools down.
  • In Arizona, Gila monsters wake up from hibernation in late February or early March.
  • During spring season, when the temperature is moderate, monsters remain active in the morning and in the afternoon. However as the temperature goes high in June the lizards search cooler and moisture surroundings.
  • Gila monsters conserve energy by spending much of its time resting and sleeping. That is not to say that monsters are lazy. It simply suggests that the animal doesn’t need to go for hunting every now and then.
  • They are known to travel 6.5 miles per year.
gila monster facts
Gila Monster ©

Feeding Ecology & Diet

  • Gila monsters are opportunistic feeders; they will eat anything ranging from small carnivores to the bird’s eggs. They will prefer to feed on baby animals which they detect by chemical odor. Monsters pick the odor by continuously flicking with their forked tongue.
  • The prey animal includes desert cottontails, frogs, insects, carrion, antelope ground squirrels, baby squirrels, and other baby rodents in the underground nests.
  • Gila monsters supplement their diet with Gamel’s quail egg, nestlings of doves, reptile eggs, and tortoise eggs. If the eggs are not too large then monsters may swallow the whole.
  • In one time, Gila monsters consume 1.5 times their own weight. They don’t eat a lot because they have low metabolism. Lizards rarely drink water but when the water is available, they do drink. The driest months are May and June in the deserts of Sonoran, Chihuahuan, and Mohave.

Reproductive Biology

  • Gila monsters reach maturity at 4 – 5 year age. At maturity, they grow to a length of about 14 – 16 inches and weighs up to one pound.
  • The young monsters are 6 – 6.5 inches long with the weight measuring just over an ounce.
  • The gestation period lasts about 45 days. There are 2 – 12 eggs in a single clutch. A female lays leathery elongate-shaped in the months of July and August.
  • Each monster’s egg measures one-half inch in length with a diameter measuring up to one-fourth inches. They weigh up to one-third ounces.
  • The incubation period lasts 10 – 12 months.
  • They grow one-fifth of an inch each year but it mainly depends on the animal’s condition and size.
  • The average lifespan of Gila monsters is 20 – 30 years in captivity.

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