Western Diamondback Rattlesnake

Western diamondback rattlesnakes are an icon of the U.S. West.

Featured in many movies, the sound of a rattlesnake is unmistakable. It’s also disturbing if you grew up in an area where you share nature with them. They’re long and heavy-bodied venomous snakes, the second-longest in North America. These snakes are reclusive and avoid people in any way they can, but bites are common because they’re common in their territory.

4 Amazing Facts About Western Diamondback Rattlesnakes

• They are the second-longest venomous snake in North America; only the eastern diamondback rattlesnake is the longest.
• You can’t count their age by their rattles; not only do they break, but western diamondback rattlesnakes can shed more than once per year.
• They can regrow their fangs several times per year.
• Males grow much larger than females and fight for the right to mate with receptive females.

Where to Find Them

Western diamondback rattlesnakes inhabit the southwestern United States and northern Mexico. They prefer living in arid desert and semi-desert conditions; they are often found hiding under vegetation or other cover items, such as rocks, branches, and debris.

Some members of this species migrate one to two miles to and from communal dens in the spring and fall. In the spring, males often fight for dominance and breeding rights. However, the snakes don’t generally injure one another during these impressive displays.

Like many vipers, western diamondback rattlesnakes are born rather than hatched. About 165 days after mating, the female gives birth to 10-20 babies, called neonates. Within a couple of hours, they head off on their own to find shelter and food. Most neonates don’t survive their first year because they’re heavily preyed upon by other species.

Scientific Name

Their scientific name, Crotalus atrox, means “horrible rattle.” Crotalus originates in Greek and means rattle, while atrox is the Latin root for our English root of “atrocious.”

Western diamondback rattlesnakes are part of the Viperidae family; and are pit vipers from the Crotalinae subfamily. They have several common names, including coon tail, buzz tail, and rattler.

Types of Diamondback Rattlesnake

Diamondback rattlesnakes get their name from their diamond-shaped markings and tail rattle. They inhabit southern portions of the United States and northern Mexico.

• Western Diamondback Rattlesnake (Crotalus atrox) occurs in the southwest United States and northern Mexico.
• Eastern Diamondback Rattlesnake (Crotalus adamanteus) lives in the southeast United States primarily Florida and Alabama.
• Red Diamondback Rattlesnake (Crotalus ruber) has three recognized subspecies, Cedros Island red diamond rattlesnake (C. r. exsul), San Lucan red diamond rattlesnake (C. r. lucasensis), and the red diamond rattlesnake (C. r. ruber). They inhabit the southwestern corner of California south to the tip of Baja California, and a few Gulf and Pacific islands near the coast.

History and Evolution

When looking at the evolution of any rattlesnake, such as a diamondback, you have to look at the pit viper’s evolution which evolved in the Miocene Era. Molecular phylogenies date Viperidae back further to the early Eocene Era around 56-48 million years ago. They originated in Africa, Asia, and Europe and later spread into North, Central, and South America.

Researchers believe there was an ancestral snake to modern rattlesnakes which existed around 22 million years ago. It had highly toxic venom composed of genes for toxins that could damage muscles, attack the nervous system, and damage the blood cells of its victims. Rattlesnakes came on the scene 12-14 million years ago but somehow shed certain neurotoxin genes, so that their venom became more specialized. For example, the venom of an Eastern or Western Diamondback rattlesnake damages muscles and blood vessels in its prey. On the other hand, the venom of the Mojave rattlesnake attacks the blood and nervous system.

As to the evolution of the rattlesnake rattle, it could have been adapted as a way to warn enemies. It perhaps could have been from excess shredded skin that produce noise as the snake moved and vibrated it.

Population and Conservation Status

Western diamondbacks aren’t endangered. They thrive in the desert southwest and have a stable population. In 2007, the IUCN assessed them for inclusion on IUCN the Redlist and listed them as Least Concern.

However, rattlesnake roundups still occur in some areas where people gather and kill as many as possible. This unfortunate practice throws local ecosystems out of balance with a dramatic loss of many predators at one time.

These snakes face several threats, including habitat destruction and predation. Many animals prey on juvenile and adult western diamondback rattlesnakes, including hawks, roadrunners, wild hogs, owls, king snakes, Texas indigo snakes (expert rattlesnake hunters), and coachwhip snakes.

Appearance and Description

These thick-bodied rattlesnakes measure about two feet long when they’re born. Western diamondback rattlesnakes often reach four feet long, but individuals five and six feet long occur occasionally. The longest on record was seven feet long. They’re relatively heavy and typically weigh between three and six pounds; very heavy individuals can weigh 15 pounds.

Most of them have a tan to grayish background color, but some are pinkish, red, or orange. Over their base color, darker blotches extend down the length of their back. These start somewhat rectangular and become diamond-shaped further down the back.

They have a stripe running diagonally down their head, starting just below their eye. Western diamondback rattlesnakes have elliptical pupils and a scale that sits over the top of their eyes. This scale is present in many viper species and lends to the “angry expression” that many people feel they exhibit.

Western diamondback rattlesnakes have strongly keeled scales that make them look dull instead of shiny. They have large, spade-shaped heads that are twice the width of their neck, and their tails have alternating black and white or gray bands that end in rattles.

Videos

Venom: How Dangerous are They?

As with other rattlesnake species, western diamondbacks only strike for defense and potential food. Left alone, these are reclusive animals that avoid people. Bites happen because it felt threatened, or that person antagonized it.

The venom of most diamondback rattlesnake species tends to be less toxic than that of other rattlesnake species. However, they can inject large amounts into victims, making their bites quite dangerous.

According to DovMed, western diamondback rattlesnake venom is “hemotoxic, myotoxic, and cytotoxic, affecting the blood and heart system and the body muscles. ” Their venom may have components that help them digest their food, so they prefer saving venom for prey animals.

Behavior and Humans

These snakes’ diet includes small mammals, including mice, woodrats, rabbits, squirrels, and occasionally birds and lizards. They’re primarily nocturnal and use heat-sensing pits between their nostrils and eyes to locate prey. During the cooler spring months, they’re active more often throughout the day, but they’re only active at night during the summer. To hunt, western diamondback rattlesnakes tuck themselves into a good hiding spot and wait for their meal to come to them. A 1976 study that followed their eating habits indicated that the bulk of their diet is small mammals.

Western diamondback snakes are not aggressive in that they won’t be chasing you down. However, they stand their ground when cornered—the distinctive rattle signaling their displeasure with your presence. They don’t always rattle a warning. Sometimes they stay quiet and try to keep hidden. They’re a little feistier than other snakes and more willing to bite. Generally, they’re happy to get away from you if you back away slowly to give them space.

Similar Animals

• Tiger Rattlesnake
• Red Diamond Rattlesnake
• Arizona Black Rattlesnake