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Crotalus atrox
One of the larger species of rattlesnake common to the arid Southwest United States. From the sheer standpoint of size it ranks as one of the world's largest and most dangerous snakes.

The diamondback primarily feeds on small rodents, rabbits, birds, and almost anything alive that can be swallowed whole.

Partly because of its wide distribution, this snake accounts for more serious and fatal snake bites than any other North American reptile.
Sizes range from new born (live, no eggs) at about 10 inches to full adults at around 60 inches. Specimens exceeding six feet are rare.
The loud buzzing rattler sound coupled with a high rising and very threatening coil is usually ample identification information for those in the field.

They are largely defensive and tend to stand their ground if provoked.A rattlesnake is classified as having hemotoxic venom that attacks the blood system of its prey.

These serpents should be considered armed and dangerous with a well-developed fang and poison delivery system.

Pictured to right is the "busines end" of the Western Diamondback Rattlesnake.

(Note the droplet of yellowish venom on the left fang.)

Rattlesnakes have a wide range of color variations with emphasis on gray, tan, and black with sometimes a strong yellowish, reddish, or greenish tone.

This captive albino specimen is approximately 4 feet in length and lacks the protective camouflage of the typical diamondback.


A diamondback on the prowl for a meal.

Notice the forked tongue. The snake uses this to "taste" the air and find its prey. Pit vipers, like the diamondback, also use heat sensitive areas in "pits" on the front of their heads to locate their victims even in total darkness.

The Western Diamondback Rattlesnake, or Crotalus atrox, a member of the family Viperidae, the subfamily Crotalinae, and the genus Crotalus, has such a hold on the human psyche that it has been a symbol of the American Southwest from prehistoric into historic times. It figures in ancient mythology, ceramics and rock art and in modern story and media.

The King of the Southwestern Rattlers

The Western Diamondback, which can exceed seven feet in length, is the king of our twenty odd species and sub-species of Southwestern desert rattlers, not only in terms of size, but also in terms of its fearsome reputation.

Malevolently handsome, its basic color ranges from brown to gray to pinkish, depending on the shade of its habitat. Its back is lined with dark diamond-shaped blotches outlined by lighter-colored scales. Its head is distinguished by two dark stripes, one on each side of its face, which run diagonally, like Zorro’s mask, from its eyes back to its jaws. Its tail is circled by several alternating black and white bands, like the pattern of a raccoon’s tail. Its patterns are most distinctive when the snake is young and are more faded, blurred and camouflaged when it is older.

Like its brethren – a clan of some 100 species of poisonous snakes generally called "pit vipers" – the Western Diamondback comes equipped with a spade-shaped head, a fiendish fang and venom system, elliptical pupils and heat-sensing facial pits. It has reserve fangs to replace any which break off in a victim. The venom causes extensive tissue damage, bleeding and swelling in humans. The pits, in effect, infrared detectors, guide the snake swiftly and surely to warm blooded prey such as rodents, even in the total darkness of the animals’ burrows. Its rattles – a distinguishing feature it shares only with other rattlesnakes – grows segment by segment, each rattle the keratin remnant of a shed skin. It can add two or three rattles each year, with each molt, although it may also break off some of its rattles in the course of a year.

Unlike the Black Tailed Rattler, which tends to be lethargic, or the Rock Rattler, which tends to be excitable but non-aggressive, the Western Diamondback will coil, rattle fearsomely, and stand its ground when threatened. It bites hundreds of people a year, more than any other venomous snake in the United States. It hunts from late evening to early morning, crawling either sinuously like other snakes or rectilinearly like a caterpillar.

Eating and Being Eaten

Like other rattlers, the Western Diamondback takes up residence among communities of small mammals such as prairie dogs, rabbits, gophers, chipmunks, ground squirrels, mice and rats, the more the better, usually hunting at night. It ambushes victims along their trails or attacks them in their burrows, sometimes striking and swallowing an animal which weighs more than the snake itself. Given the opportunity, the snake will also eat birds. After feeding, the snake can go several weeks before feeding again.

The Western Diamondback, especially the juvenile, often comes under attack itself. It may become a meal for an eagle, a hawk, a roadrunner or a wild turkey; for a kingsnake or a whipsnake; or for a coyote, a fox, a badger or a feral hog. Regarded as an enemy and a threat, it may be trampled to death by a deer, an antelope, a cow, a horse or even a sheep. The Western Diamondback lives in a rough neighborhood.

Habitat and Range

The snake occupies diverse habitats from sea level to 7000 feet, ranging from desert flats to rocky hillsides, grassy plains, forested areas, river bottoms and coastal prairies. (Yes, the snake can swim quite nicely, holding its rattles above the water to keep them dry.) Its range spans much of Arkansas, most of Texas and Oklahoma, the southern parts of New Mexico and Arizona, the southern tip of California, and the northern parts of Mexico’s Chihuahua and Sonora.


The Western Diamondback male, like the males of most species, become obsessed with females at mating time, in the spring. He pursues the female incessantly. Should he encounter another male, the two will wrap around each other in a serpentine wrestling contest, rearing and falling and body slamming until one or the other concedes defeat. Once inseminated, the female, sexually mature at three years old, will bear her brood live, in late summer. The young are born complete with fangs and venom, armed and dangerous at birth. A good thing. The mother abandons them upon delivery.


With the coming of the shortening days and falling temperatures of autumn, the Western Diamondbacks head for the community den – a cave or rocky recess – where they will hibernate for the winter. In colder areas, they come by the hundreds; in warmer areas, by the dozens. They emerge in spring, sexually driven, hungry and mean.

Southern Pacific Rattlesnake

Southern Pacific Rattlesnake
(Crotalus helleri)

Physical Description

The Southern Pacific Rattlesnake can reach a little over 5 feet in length. It has dark brown to black-colored blotches that are bordered by a lighter brown or pale color. These blotches run down the entire length of the back, turning into bands at the tail. The triangular shape of their head and the rattle on the end of their tail tells all that this snake is poisonous

Range and Habitat

The Southern Pacific Rattlesnake is sub-species of the Western Rattlesnake and is found primarily in the southwest. Preferred habitat ranges from brush covered land to coastal sand dunes. Rock outcrops, rocky stream courses and ledges are where you are most likely to run into them.


The rattlesnakeļæ½s diet consists mainly of rats, mice and other small rodents.


The mating season occurs March through May. The young are born in the fall. There can be as many as 4 to 21 born at a time. They are born alive and left on their own. The young snakes are 6 to 12 inches at birth.


The rattlesnake has always had a bad reputation. This venomous snake rarely bites humans unless they have chosen to disturb, tease or try to pick up the snake. Most often the snake makes a willing retreat. When cornered the snake will coil and rattle its tail as a warning. It will raise its neck in an s-shape high above the coil allowing it to gain elevation for aiming and striking. Since reptiles cannot regulate their own body temperature, snakes go through winter dormancy from November to March. During the day they will lay in the sun warming themselves. As their body heats up they will move about in search of dinner. They will hunt at dusk and sleep until morning.

Western Rattlesnake, San Diego County, photographed by Bradford Hollingsworth

Crotalus viridis
Western Rattlesnake


Crotalus comes from the Greek crotalon, a rattle or little bell; viridis is Latin for green.


Size: The Western Rattlesnake can reach lengths slightly over 4 feet, but 2 1/2 feet is more the norm.

Coloration: The Western Rattlesnake (Crotalus viridis) is a widely distributed and highly variable species. In our region, this snake is lighter gray or brown. Pale margins edge the pattern of its dark dorsal blotches. In some individuals, the pale margins can be yellow, giving the snake a greenish cast. Specimens from high elevations can be a velvety, jet black with only a slight hint of patterning. A light stripe runs from outside corner of the eye to the corner of the mouth, and the tail has dark rings. Juveniles have a yellowish tail, and their dorsal patterning contrasts more than that in adults.

Subspecies: There are as many as nine subspecies. Only the Southern Pacific Rattlesnake (C. v. helleri) and the Los Coronados Island Rattlesnake (C. v. caliginis) occur in our region.

Range and Habitat

The Western Rattlesnake is distributed across most of the western United States, Mexico, and Canada. The Southern Pacific Rattlesnake (C. v. helleri) is distributed from southern California to the central part of the Baja California. The Los Coronados Island Rattlesnake (C. v. caliginis) is found only on the southern island of the Coronados Islands, off the Pacific coast of northern Baja California.

In southern California, this species is cismontane,(In California and Baja California, the region between the Pacific coast and the ridge of the mountains. The desert side of the mountains is called "transmontane.") and is not found on the eastern slopes of the mountains. The Western Rattlesnake enjoys a wide range of habitats from seacoast to pine wooded mountain heights, and is tolerant of disturbed areas. It is the most abundant rattler of our region, west of the desert.

Natural History

Behavior: In early spring, the Western Rattlesnake basks in the sun or glides around as it looks for food and mates. In dense chaparral, where little sun reaches the ground, it may climb to the tops of bushes to bask. As the weather warms, it becomes more active at dusk or at night.

Prey and Predators: Their diet includes small mammals, birds, reptiles and amphibians.

Breeding: A female may bear 4 to 12 young in late summer.

Conservation Status

There has been no proposed conservation status. Because of widespread negative attitudes towards snakes, very few conservation programs, worldwide, have been created. A much higher percentage of snakes are threatened with extinction then is currently recognized. Therefore, snakes are particularly suspectible to being overlooked by conservation-minded biologists.

Los Coronados Island Rattlesnake
(Crotalus viridis caliginis)

Freakshow, (Bob)

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