Crotalus oreganus - Western rattlesnake

Meaning
C. o. abyssus - comes from Latin meaning no bottom or bottomless, refering to the Grand Canyon.
C. o. caliginis - "caliginis" means mist, fog, darkness or blindness.
C. o. concolor - from Latin meaning; of the same color or of uniform color.
C. o. helleri - honouring Edmund Heller.
C. o. lutosus - muddy, full of mud – possibly referring to the dorsal colors.
C. o. oreganus - found in the state of Oregon - referring to the locality.

English name
Western rattlesnake

Distribution
This snake has a tremendous range, from southwestern Canada, through most of the western part of the United States into northern Mexico. They are also found on islands along the pacific coast line.

Habitat
Seen there large range they cover a variety of habitats including rocky hillsides, talus slopes and outcrops, stream courses, rocky areas in grasslands, grassy plains, mixed woodlands, montane forests, pinyon juniper, sagebrush, desert like areas even seaside dunes and agricultural areas.

Description
C. o. abyssus - Grand Canyon rattlesnake can be found in Arizona and Utah in the Colorado River system of the Grand Canyon. The ground color tends to be salmon/pinkish gray with a yellowish tan. In juviniles the rounded body blotches are often well defined but may fade with age. The blotches have dark borders whereby the interior darkens almost matching the ground color of the animal. Adults usually don’t grow larger then 1 meter.
C. o. caliginis - Coronado Island rattlesnake is found on Isla Coronado del Sur, off the coast of Baja California. An ash/dark grey or olive green ground color covered with sharp dark well defined iregular blotches. The dark postocularstripe runs over the supraocular sometimes fusing in the middle. The top of the head is usually paler then the rest of the body. Averge size for adults is around 80cm.
C. o. concolor - Midget faded rattlesnake is found in the Colorado and Green River basins covering the states Wyoming, Utah and Colorado. Individuals usually have a light yellow ground color but some are pink or reddish colored. The dorsal blotches are often a darker tone than the ground color and may have some white edges. Some individuals appear patternless. Adults normally don’t grow larger then 65cm.
C. o. helleri - Southern Pacific rattlesnake lives in the state California and in the northern Baja California region of Mexico. Their ground color varies from greenish, brown, black or gray, whereby specimens from lower elevations tend to be lighter and more gray or tan, where as others more inland and in the higher elevations are darker, sometimes almost completely black. The dark diamondshaped blotches are usualy outlined by a lighter colors and turn into rings toward the tail. The last ring is usually twice (or more) the width of the other rings and youngster often have a yellow/orange tail (some lokations do not). Adult usualy remain between 90 – 130cm.
C. o. lutosus - Great Basin rattlesnake lives like the name in the Great Basin region, this includes several states Idaho Utah, Arizona Nevada, California and Oregon. The ground color usually matches the environment, resulting in a grey, light tan brown, yellow, pinkish overal color with dark dorsal blotches, which often have light centers. The top of the head is usualy dark colored. With age the pattern may fade. Adults usually remain between the 90-120cm.
C. o. oreganus - Northern Pacific rattlesnake range starts in British Columbia, Canada, south through the United States covering the states Washington, Idaho, Oregon and California. The variable background colors often matching the environment range from olive-green, gray, brown, golden, reddish brown, yellowish, to almost white with dark red-brown/black blotches. The dorsal blotches change to dark bars after 2/3 of the body and form dark and light well-defined rings on the tail which are fairly uniform in width A dark eyestripe with light borders runs from the eye to the corner of the mouth. Adult usually range between 90 - 120 cm.

Diet
All of the subspecies eat a variety of small mammals and other animals living in their region, including ground squirrels, mice, rats, rabbits birds and even lizards, snakes, frogs and insects.

Venom
All of the venoms are quite similar except for C. o. helleri which is known to have neurotoxins but C. o. concolor which also has a neurotoxine "concolor toxin" is considerd, drop for drop, the most venomous of the group. Overall effects are pain, ecchymoses, paresthesias, muscle fasciculations, blistering, change in taste and vision, clotting problems and victims may go into shock. Necrosis is quite common, sometimes resulting in amputation.

Extra
Although at one time this group fel under C. viridis this whole group is still being studied, C. o. caliginis may be dropped into C. o. helleri.
Crofab is not very effective against venom bites of C. o. helleri often requiring more than 40 vials, one person has received 66 vails of Crofab after a C. o. helleri bite.
The subspecies that have bordering/overlapping ranges are know to intergrade with each other.