Arizona Black Rattlesnake

This venomous snake is usually between two and four feet long. The adults are dark brown to almost black, and juveniles are more brightly patterned. They live in the forests of Arizona and western New Mexico at altitudes above 4,000 feet.

3 Amazing Facts About Arizona Black Rattlesnakes

• These snakes are social, and each individual seeks out their preferred community size; some in larger communities, some in smaller communities, and others spend most of their lives solo.
• They can change color! Arizona black rattlesnakes change colors depending on their mood.
• Females may birth their brood together and stay with each other until the neonates leave the nest.

Where to Find Arizona Black Rattlesnakes

Arizona black rattlesnakes live at high altitudes in heavily forested areas of Arizona and western New Mexico. They thrive in cooler, moister conditions that the forests offer.

They are often coiled up in leaf litter or under rocks, waiting for a meal to stumble near enough to strike. Many people say that they look like cow pies until they get close enough to spot their rattles and pitviper heads.

These snakes are most active from late March to late October. They retreat to a communal den to hibernate between late October and early March. Each year, they return to the same den, with young and mature snakes sharing hibernation space.

Arizona black rattlesnakes appear to have some maternal instincts. As with other pit vipers, females stay with their young after birth for seven to 14 days or until their first shed. Scientists say that females sometimes cooperatively parent their young.

A group of researchers discovered this for themselves when they began photographing a female and her brood in Arizona. A typically passive female, this snake “Poked her head out of her shelter and then proceeded to crawl from her refuge toward us, still rattling, and glaring directly at us. Our once-placid Woody was now fearless and wanted us to know she would not tolerate our advance.”

Scientific Name

The Arizona black rattlesnake’s scientific name is Crotalus cerberus, with its genus name describing its rattle (Crotalus). The specific epithet, cerberus, means spotted and originates in Greek with Kerberos. In Greek mythology, Cerberus was the three-headed guardian of the Underworld. In 1875, Elliot Coues described it as “Particularly repulsive due to the great size to which it attains, the caliber of the body, and the black color.” Coues called it the black rattlesnake, and the name stuck.

It is endemic to Arizona and far western New Mexico, so it’s commonly called the Arizona black rattlesnake. Although many people also call it a timber rattlesnake because of where it lives, this isn’t the timber rattlesnake of central and eastern United States. That is a different species: Crotalus horridus.

Evolution and History

The Arizona black rattlesnake is a member of the Crotalus genus of venomous pit vipers in the family Viperidae, which scientists believe originated between 56 million and 48 million years ago in the early Eocene.

There are a few theories on how rattlesnakes’ rattles evolved. One is their rattling behavior began with a defensive method, with the snakes rustling leaf litter to startle bison who shared their original habitats. Another is that the snakes’ excess shredded skin produced noise that could ward off predators. Snakes are thought to have developed keratin callouses on their tails, creating genetic differences that led to the evolution of rattles.

The Arizona black rattlesnake was formerly classified as a subspecies of the prairie rattlesnake (Crotalus viridis) before being elevated to a full species.

Population and Conservation Status

The National Parks Service completed a survey from 2003 to 2005 and determined that the species is relatively rare. Unfortunately, the species’ rarity made it impossible to collect enough information to estimate their population. However, the New Mexico Department of Game & Fish listed them as a “Species of Greatest Conservation Need (SGCN)” in the State Wildlife Action Plan for New Mexico (NMDGF 2016).

The IUCN has not assessed the Arizona black rattlesnake for inclusion in the IUCN Redlist.

Appearance and Description

The Arizona black rattlesnake is one of 13 rattlesnakes that are present in Arizona. This snake is a medium size, heavy-bodied, and has a spade-shaped head. Juvenile Arizona black rattlesnakes have a base color that is light gray or brown with dark brown to black blotches that are roughly oval to rectangle-shaped running down the length of their backs that can end in bands around the tail. In addition, they have dark lines on the side of their heads, bordered by white or grayish-white, that usually cross over the top of their snout. The lines sweep back diagonally downward, and the dark line continues to the end of their jaw, the effect of which is a masked appearance.

Over time, the snakes darken and become brown or nearly black, making their patterns difficult or impossible to see.

Some Arizona black rattlesnakes have a unique ability: they can rapidly change colors under certain conditions. For example, a nearly black snake becomes a gray snake with a clear pattern in a few minutes, then back to normal when they relax. In addition, captive snakes sometimes lighten after feeding, and stressful events like being captured can trigger a color change.

That’s not the only fascinating thing about their rapid color change! They also appear able to control the color change, and some exhibit darker coloring during the day and lighter at night.

Venom: How Dangerous is the Arizona Black Rattlesnake?

Like all rattlesnake species, they have a very advanced venom-delivery system. Rattlesnakes have fangs hinged at the base that fold up into their mouths. Like a hypodermic needle, their fangs are hollow and directly attached to venom glands. This structure allows rattlesnakes to grow much larger fangs that inject venom deeply into their victim.

These rattlesnakes are considered moderately venomous, and a bite from one requires immediate medical care. However, they are not aggressive snakes; they are pretty docile. Most bites occur on the hands and feet because someone stepped on or otherwise harassed them.

Behavior and Humans

This species was the first that scientists observed exhibiting social behavior, such as communal parenting, sharing basking locations, and interacting with other snakes of its species. They often nest with other snakes, sharing den space, and the females share parenting duties.

Most interactions with humans and Arizona black rattlesnakes happen when the snake passes through camping areas and across roads or paths. This snake will move along quickly if given the time to do so and doesn’t want to be near people.

Similar Animals

• Ornate Rattlesnake
• Western Diamondback Rattlesnake
• Tiger Rattlesnake
• Red Diamond Rattlesnake

1. Arizona Black Rattlesnake Bite | DovMed, Available here: https://www.dovemed.com/diseases-conditions/arizona-black-rattlesnake-bite/
2. Social Behavior of Arizona Black Rattlesnakes | Snakes.ngo, Available here: https://www.snakes.ngo/arizona-black-rattlesnake-aggregations-exhibit-hallmarks-of-sociality/
3. Arizona Black Rattlesnake | Mark Allen Davis, Available here: https://www.researchgate.net/publication/306392551_Rattlesnakes_of_Arizona_-_Arizona_Black_Rattlesnake_Crotalus_cerberus_Coues_1875
4. Reptile Database, Available here: https://reptile-database.reptarium.cz/species?genus=Crotalus&species=cerberus
5. Advocates for Snake Preservation, Available here: https://www.snakes.ngo/wp-content/uploads/2021/07/Buzz-07.pdf