North and South America. Most rattlesnakes are concentrated in the southwestern United States.


Mainly grasslands, scrub brush, rocky hills, deserts, swamplands, and meadows.

Beautiful and misunderstood

Rattlesnakes! The word alone fills most people with fear and anxiety, because they have no experience in dealing with snakes. Yet we should learn to appreciate the rattlesnake as one of the most efficient and specialized predators on Earth. Many rattlesnakes struggle to survive as humans move in on their habitat. And some people feel that the only good rattlesnake is a dead one! Read on to discover cool stuff about rattlesnakes and why we need them.

About that rattle

Rattlesnakes are known for their relatively heavy bodies and diamond-shaped heads. They are considered to be the newest or most recently evolved snakes in the world. Rattlesnakes have either a rattle or a partial rattle made of interlocking rings, or segments of keratin, the same material our fingernails are made of. When vibrated, the rattle creates a hissing sound that warns off potential predators. It is an extremely effective and highly evolved predator-avoidance system. Another rattlesnake characteristic is the "pit" on each side of the head, which is a heat-sensitive organ for locating prey.

A rattlesnake can detect prey that is as little as 1/10 of a degree warmer than its background.
The Santa Catalina Island rattlesnake has no rattle, just a small button! It climbs trees and sneaks up on its bird prey, which is easier without a noisy rattle.
Who would guess that rattlesnakes are good swimmers? They’ve been found several miles out at sea.
The San Diego Zoo was the first facility in the world to hatch the Aruba Island rattlesnake.

Rattlesnakes have been a part of the San Diego Zoo since our earliest days, with most of them collected from San Diego County. Often, these local rattlers were used to trade with zoos to obtain other animal species. Laurence Klauber, who was curator of reptiles during the San Diego Zoo’s early years, once said that rattlesnakes “command a sort of fearsome interest, even among people who certainly had no fondness for them.” He lends his name to the banded rock rattlesnake’s scientific name, Crotalus lepidus klauberi, and in 1956, he published the definitive two-volume Rattlesnakes: Their Habits, Life Histories, and Influence on Mankind. Our Klauber-Shaw Reptile House is named in his honor.

In 1948, the first captive breeding of the Aruba Island rattlesnake occurred at the Zoo. At one time or another, we have displayed all the rattlesnake species native to the U.S. We currently are home to 13 rattlesnake species, representing rattlers found both near and far. You can view them in our Reptile House, our Reptile Walk, and in Elephant Odyssey.

Snake reproduction study
Surprisingly, little is known about basic snake reproduction, so in 2006, San Diego Zoo Global initiated a project to gather reproductive data and develop assisted reproductive technology using local Southern California snakes. The San Diego Zoo Safari Park’s undeveloped land is home to 16 snake species, including 3 rattlesnake species. For over a year, these local rattlesnakes were caught, weighed and measured, and tagged with a small numbered label inserted inside the rattle, closest to the tail. Their reproductive status was assessed before they were released back where they were found.

The data collected represents a significant addition to the body of knowledge on snake reproduction. The techniques of semen collection, cryopreservation, and ovarian ultrasound developed with the help of these rattlesnakes have benefitted conservation efforts for six endangered snake species in Brazil. Ongoing studies at three field sites in that country are generating data on the ecological requirements, health, demographics, and feeding behavior of these rare reptiles.

Living with rattlers
The Santa Catalina Island rattlesnake Crotalus catalinensis and the Aruba Island rattlesnake Crotalus unicolor are at critical risk, due to the fact that they are each found only on one small island and have been over-collected for the illegal trade market or killed. Other species are in decline simply because people fear them. The San Diego Zoo is working with the Los Angeles Zoo and Mexico to collect endangered Santa Catalina Island rattlesnakes to learn more about them and help rebuild their population.

By using common sense, we can share our open spaces with rattlesnakes. These beautiful animals are important to the environment, because they control rodent populations. Let’s protect them and see them as solutions to problems rather than as misunderstood animals we fear and want to eliminate. Just a little care in where we put our feet when we are out hiking is all that is necessary for us to coexist with this fascinating predator.