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    National Park Arizona

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  • Tucson Mountain District Roads Closed Due to Flash Flooding

    Several interior roads, including the scenic loop, are closed in Tucson Mountain District (west) due to severe storms and flash flooding on August 26th. Roads will remain closed until further notice. Check the park's facebook page for updated information More »

  • Labor Day Run - Rincon Mountain District Road Closure - Sept. 1st

    Due to the Annual Labor Day Run, Saguaro National Park's Rincon Mountain District Loop Drive will be closed from 4:00am to approx 10:30am on Sept. 1, 2014. Please be advised of vehicle congestion along roadsides when approaching the park during this time. More »

Gila Monster

Gila monster


Gila Monster (Heloderma suspectum)

Gila Monsters are one of only two venomous lizards in the world! They produce venom in glands of the lower jaw and channel it along grooves in the teeth for secretion. Once a Gila monster bites, it generally holds on tight, chewing more and more venom into the bite. The venom is believed to be a defensive weapon as most of the lizard’s prey is defenseless.

Gila monsters are most active during daylight from spring through fall, but they spend up to 98 % of their time in their burrows. When they are above ground, they tend to move rather slowly and will first try to escape if a predator comes near. They will also hiss and open their mouths very wide (this behavior is called gaping), showing off their pointy teeth. They bite only as a last resort. The bite is extremely painful to humans but rarely fatal. Most human bites occur when someone purposely aggravates or tries to handle a Gila monster. If left alone, they are harmless.

Body size: 9-14 in. (22.8-35.5 cm)

Diet: Small and young mammals (baby rabbits, for example), nestling birds and eggs, reptile eggs, and carrion

Did You Know?


The average life span of a saguaro cactus is 150 years, but some plants may live more than 200 years. A 20 foot tall saguaro weighs approximately 1 ton (2000 pounds).