Gila Monster

Heloderma suspectum

Reptile

Transcript:

Today on Animal Fact Files we’re talking about gila monsters. These amazing lizards are found in the south western United States and northwestern Mexico. They come with pebbly looking skin which closely matches that of their relative, the Mexcian beaded lizard - we’ll get to them in a future video.

Gila monsters are the largest living lizards native to the US. They average anywhere from one to more than one and a half feet (30.5 to 46 centimeters) in length from nose to tip of their tail and can weigh over a pound (450 grams). A gila monster’s tail is short and sausage shaped, and like the rock monitors we’ve talked about previously, gila monsters can store fat in their tails! In fact, a healthy gila monster can live for a year after only eating three or four meals - but more on their diets in just a bit.

Gila monsters are active from March to November and they spend the winter months in a state of rest. Even during their “active” months, however, gila monsters may spend more than 95% of their time hanging out in burrows. These lizards may dig their own burrows, but they’re more likely to take over a burrow left behind by another animal. Gila monsters spend so much time in their burrows to help regulate their body temperatures.

These lizards are found in desert-like regions - perhaps among a field of saguaros, or in the rocks at the foot of a mountain. They’re diurnal, but they’ll spend the most extreme parts of the day hiding from the heat. Gila monsters are generally considered terrestrial animals, and while they have been seen climbing small scrub trees, they’re most likely to be seen basking in the sun at the entrances to their burrows.

The breeding season for gila monsters begins in April and continues through June. During this time, males and females may share a burrow. The males will fight each other over females, taking each other on in intertwined dances not unlike some snake species. These lizards have insane stamina and these matches may go on for hours! Once the victor is decided, he’ll move in with his girl. There isn’t a lot of information on wild gila monster nesting habits. It’s known that the nest size averages five to six eggs, but it can more than double that. The eggs are laid sometime between July and August, but the babies won’t appear from the burrow until May of the following year.

What happens in the nest during that time? As of this recording, the question hasn’t been answered. The eggs may overwinter with the babies hatching and emerging in spring. Another possibility is that the babies hatch but remain in the nest until conditions are more optimal, similar to the pond sliders we’ve discussed in a previous episode.

Whatever the case, it’s a solid eight to ten months before the babies come out, at which point they get busy hunting. A gila monster may travel upwards of a mile (1.6 kilometers) to find food. When they do find a meal, gila monster juveniles can consume up to 50% of their body weight in a single sitting. And they can survive off this single meal for months if needed! Though gila monsters are known as some of the world’s only venomous lizards, they don’t actually use their venom for catching prey. They don’t need to. Gila monsters hunt easy targets. The eggs of ground nesting birds as well as the nestlings of mammals such as rabbits and squirrels are the gila monster’s main course. No need to use venom on such a defenseless meal. Where a gila monster’s venom does come into play, though, is when the lizard itself needs to put up some defense.

Gila monsters are generally considered sluggish animals. If they feel threatened, they’ll hiss and posture at an imposer to try and warn of their gnarly bite. If this isn’t enough to scare away an attacker, the gila monster will bite down with sharp teeth. These teeth come with grooves that direct the venom from the gila monster’s lower jaw (yes, this is opposite to snakes) into the wound. In humans, this causes pain, bleed, and vomiting among other symptoms - in smaller animals it may prove fatal! If a gila monster can fend itself from attackers, it may live to be twenty years old in the wild.

For more facts on gila monsters, check out the links in the description. Thank you to Charlie Yang and Gregory Murphy for today’s request. Give a thumbs up if you learned something new today, and thank you for watching Animal Fact Files.