Common names: western rattlesnake, northern Pacific rattlesnake, Pacific rattlesnake, more.

Crotalus oreganus is a venomous

Venomous snake

"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...

 pitviper

Crotalinae

The Crotalinae, commonly known as "pit vipers" or crotaline snakes, are a subfamily of venomous vipers found in Asia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head...

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 found in North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 in the western United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, parts of British Columbia

British Columbia

British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

 and northwestern Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. Seven subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 are currently recognized, including the nominate subspecies described here.

Description

The size of this species varies greatly, with some populations being stunted and others growing very large. Mainland specimens often reach 100 cm in length, with the largest on record being 162.6 cm (Klauber, 1956) for C. o. oreganus.

This species, in its various forms, shows considerable ontogenetic variation. Juveniles usually have more or less distinct patterns, but this fades as the animals mature. The color of the iris often matches the ground color, which may be bronze, gold, different shades of tan, pink or gray.

The color pattern of the typical form, C. o. oreganus, has a dark brown, dark gray, olive brown, and sometimes black or pale yellowish ground color. This is overlaid dorsally with a series of large dark blotches with uneven white edges. These blotches are also wider than the spaces that separate them. Additionally, there is a lateral series of blotches that are usually darker than the dorsal blotches and clearly visible on all but the darkest specimens. The first rings of the tail are about the same color as the last body blotches, but these become progressively darker; the last two, at the base of the tail, are usually black. The belly is pale yellow, usually with brown spots. A large dark brown blotch on the snout has a pale border behind it that forms transverse bars on the supraoculars. There is a dark brown postocular stripe with a white border that extends from the eye to around the angle of the jaw.

Common names

Western rattlesnake, northern Pacific rattlesnake, Pacific rattlesnake, black rattlesnake, Arizona diamond rattlesnake, black diamond rattlesnake, black snake, California rattlesnake, confluent rattlesnake, diamond-back rattlesnake, Great Basin rattlesnake, Hallowell's rattlesnake, Missouri rattlesnake, Oregon rattlesnake, Pacific rattler, rattlesnake, southern rattlesnake, western black rattlesnake, western rattler, north Pacific rattlesnake.

Geographic range

Found in North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 from southwestern Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, through much of the western half of the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, and south into northern Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. In Canada it is found in southern British Columbia

British Columbia

British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

. In the USA it occurs in Washington, Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

, western and southern Idaho

Idaho

Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....

, California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, Nevada

Nevada

Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...

, Utah

Utah

Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

, Arizona

Arizona

Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

, and likely west-central New Mexico

New Mexico

New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...

. In northern Mexico it is found in western Baja California and the extreme north of Baja California Sur

Baja California Sur

Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises...

, from sea level to an altitude of 2,500 m.

There are also reports of this species occurring on six different islands:

• Morro Rock
  Morro Rock
  Morro Rock is a volcanic plug located just offshore from Morro Bay, California, at the entrance to Morro Bay Harbor. A causeway connects it with the shore, effectively making it a tied island. The area surrounding the base of Morro Rock can be visited. The rock is protected as the Morro Rock State...
  
  , Morro Bay
  Morro Bay, California
  Morro Bay is a waterfront city in San Luis Obispo County, California, United States. As of the 2010 census, the city population was 10,234, down from 10,350 at the 2000 census.- History :...
  
  , San Luis Obispo County, California
  San Luis Obispo County, California
  San Luis Obispo County is a county located along the Pacific Ocean in the Central Coast of the U.S. state of California, between Los Angeles and the San Francisco Bay Area. As of the 2010 census its population was 269,637, up from 246,681 at the 2000 census...
  
   (now connected to the mainland by a causeway).
• Anaho Island
  Anaho Island
  Anaho Island is an island in Pyramid Lake, Nevada, USA, on the Pyramid Lake Indian Reservation. It is located in the southeastern part of the lake, approximately four miles east of the community of Sutcliffe...
  
  , Pyramid Lake, Washoe County, Nevada
  Washoe County, Nevada
  Washoe County is a county located in the U.S. state of Nevada. The population was 421,407 at the 2010 census. Its county seat is Reno. Washoe County includes the Reno-Sparks metropolitan area.-History:...
  
  .
• Rattlesnake Island
  Rattlesnake Island (Clear Lake)
  Rattlesnake Island is an island located on Clear Lake in Lake County, northern California. Its land area is nominally , but may vary significantly as lake levels rise and fall...
  
  , Clear Lake, Lake County, California
  Lake County, California
  Lake County is a county located in the north central portion of the U.S. state of California, north of the San Francisco Bay Area. It takes its name from Clear Lake, the dominant geographic feature in the county and the largest natural lake wholly within California...
  
   (may no longer be found here).
• Santa Catalina Island, California
  Santa Catalina Island, California
  Santa Catalina Island, often called Catalina Island, or just Catalina, is a rocky island off the coast of the U.S. state of California. The island is long and across at its greatest width. The island is located about south-southwest of Los Angeles, California. The highest point on the island is...
  
  , off the coast of San Pedro, Los Angeles, California
  San Pedro, Los Angeles, California
  San Pedro is a port district of the city of Los Angeles, California, United States. It was annexed in 1909 and is a major seaport of the area...
  
  .
• South Coronado Island, off the coast of Baja California
  Baja California
  Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
  
  .
• Mare Island
  Mare Island
  Mare Island is a peninsula in the United States alongside the city of Vallejo, California, about northeast of San Francisco. The Napa River forms its eastern side as it enters the Carquinez Strait juncture with the east side of San Pablo Bay. Mare Island is considered a peninsula because no full...
  
  , Vallejo, California
  Vallejo, California
  Vallejo is the largest city in Solano County, California, United States. The population was 115,942 at the 2010 census. It is located in the San Francisco Bay Area on the northeastern shore of San Pablo Bay...
  
   (now connected by a land bridge).

Conservation status

This species is classified as Least Concern (LC) on the IUCN

World Conservation Union

The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...

 Red List of Threatened Species

IUCN Red List

The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

 (v3.1, 2001). Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is stable. Year assessed: 2007.

Subspecies

Subspecies	Taxon author	Common name	Geographic range
C. o. abyssus	Klauber Laurence Monroe Klauber Laurence M. Klauber , was an American herpetologist, and was considered to be the foremost authority on rattlesnakes... , 1930	Grand Canyon rattlesnake	The United States United States The United States of America is a federal constitutional republic comprising fifty states and a federal district... , in Arizona Arizona Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...  in the Grand Canyon Grand Canyon The Grand Canyon is a steep-sided canyon carved by the Colorado River in the United States in the state of Arizona. It is largely contained within the Grand Canyon National Park, the 15th national park in the United States...  of the Colorado river Colorado River The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states... , from the north to the south rim.
C. o. caliginis Crotalus oreganus caliginis Crotalus oreganus caliginis is a venomous pitviper subspecies endemic to South Coronado Island, Mexico.-Geographic range:Known only from the type locality, given as "South Coronado Island, off the northwest coast of Baja California, Mexico."...	Klauber, 1949	Coronado Island rattlesnake	Mexico Mexico The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of... , on South Coronado Island, off the northwest coast of Baja California Baja California Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North... .
C. o. cerberus Crotalus oreganus cerberus Crotalus oreganus cerberus is a venomous pitviper subspecies found in the southwestern United States.-Description:According to Wright and Wright , adults grow to an average length of 78-109 cm...	(Coues Elliott Coues Elliott Coues was an American army surgeon, historian, ornithologist and author.Coues was born in Portsmouth, New Hampshire. He graduated at Columbian University, Washington, D.C., in 1861, and at the Medical school of that institution in 1863...  In Wheeler, 1875)	Arizona black rattlesnake	The United States, in Arizona from the Hualpi Mountains and Cottonwood Cliffs in the northwest of the state, southeast to the Santa Catalina Santa Catalina Mountains The Santa Catalina Mountains, commonly referred to as the Catalina Mountains, are located north, and northeast of Tucson, Arizona, United States, on Tucson's north perimeter. The mountain range is the most prominent in the Tucson area, with the highest average elevation... , Rincon Rincon Mountains The Rincon Mountains are a significant mountain range east of Tucson, Pima County, Arizona, in the United States. The Rincon Mountains are one of five mountain ranges surrounding the Tucson valley... , Pinaleno Pinaleno Mountains The Pinaleño Mountains, or the Pinal Mountains, are a remote mountain range in southeastern Arizona. They have over of vertical relief, more than any other range in the state. The mountains are surrounded by the Sonoran-Chihuahuan Desert. Subalpine forests cover the higher elevations...  and Blue Mountains. Also found at Steeple Rock, in extreme western New Mexico New Mexico New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S... .
C. o. concolor Crotalus oreganus concolor Crotalus oreganus concolor is a venomous pitviper subspecies found in the western United States. A small species known for its faded color pattern.-Description:Grows to a maximum length of 750 mm...	Woodbury, 1929	Midget faded rattlesnake	The United States, in the Colorado Colorado River The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...  and Green River Green River (Utah) The Green River, located in the western United States, is the chief tributary of the Colorado River. The watershed of the river, known as the Green River Basin, covers parts of Wyoming, Utah, and Colorado. The Green River is long, beginning in the Wind River Mountains of Wyoming and flowing...  basins. This area covers southwestern Wyoming Wyoming Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High... , Utah Utah Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...  east of long. 111° West (excluding the southeastern corner) and extreme east-central Colorado Colorado Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains... .
C. o. helleri	Meek Seth Eugene Meek Seth Eugene Meek was an American ichthyologist at the Field Museum of Natural History in Chicago. He was the first compiler of a book on Mexican freshwater fishes. Together with his assistant, Samuel F. Hildebrand, he produced the first book on the freshwater fishes of Panama.He often collaborated... , 1905	Southern Pacific rattlesnake	The United States in southern California California California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area... , and Mexico in northern Baja California, west of the desert. In the north from the counties of San Luis Obispo San Luis Obispo County, California San Luis Obispo County is a county located along the Pacific Ocean in the Central Coast of the U.S. state of California, between Los Angeles and the San Francisco Bay Area. As of the 2010 census its population was 269,637, up from 246,681 at the 2000 census...  and Kern Kern County, California Spreading across the southern end of the California Central Valley, Kern County is the fifth-largest county by population in California. Its economy is heavily linked to agriculture and to petroleum extraction, and there is a strong aviation and space presence. Politically, it has generally... , and south through the counties of Santa Barbara Santa Barbara County, California Santa Barbara County is a county located in the southern portion of the U.S. state of California, on the Pacific coast. As of 2010 the county had a population of 423,895. The county seat is Santa Barbara and the largest city is Santa Maria.-History:... , Ventura Ventura County, California Ventura County is a county in the southern part of the U.S. state of California. It is located on California's Pacific coast. It is often referred to as the Gold Coast, and has a reputation of being one of the safest populated places and one of the most affluent places in the country... , Los Angeles Los Angeles County, California Los Angeles County is a county in the U.S. state of California. As of 2010 U.S. Census, the county had a population of 9,818,605, making it the most populous county in the United States. Los Angeles County alone is more populous than 42 individual U.S. states...  (including Santa Catalina Island Santa Catalina Island, California Santa Catalina Island, often called Catalina Island, or just Catalina, is a rocky island off the coast of the U.S. state of California. The island is long and across at its greatest width. The island is located about south-southwest of Los Angeles, California. The highest point on the island is... ), southwestern San Bernardino San Bernardino County, California San Bernardino County is a county in the U.S. state of California. As of the 2010 census, the population was 2,035,210, up from 1,709,434 as of the 2000 census... , Orange Orange County, California Orange County is a county in the U.S. state of California. Its county seat is Santa Ana. As of the 2010 census, its population was 3,010,232, up from 2,846,293 at the 2000 census, making it the third most populous county in California, behind Los Angeles County and San Diego County... , western Riverside Riverside County, California Riverside County is a county in the U.S. state of California. One of 58 California counties, it covers in the southern part of the state, and stretches from Orange County to the Colorado River, which forms the state border with Arizona. The county derives its name from the city of Riverside,... , San Diego San Diego County, California San Diego County is a large county located in the southwestern corner of the US state of California. Hence, San Diego County is also located in the southwestern corner of the 48 contiguous United States. Its county seat and largest city is San Diego. Its population was about 2,813,835 in the 2000...  and extreme western Imperial Imperial County, California Imperial County is a county located in the Imperial Valley, in the far southeast of the U.S. state of California, bordering both Arizona and Mexico. It is part of the El Centro Metropolitan Area, which encompasses all of Imperial County. The population as of 2000 was 142,361. The county seat is the... . From there its range extends south though Baja California to lat. 28° 30' North.
C. o. lutosus Crotalus oreganus lutosus Crotalus oreganus lutosus is a venomous pitviper subspecies found in the Great Basin region of the United States.-Description:Adult specimens are 66-121 cm in length, but rarely exceed an overall length of 1 m...	Klauber, 1930	Great Basin rattlesnake	The United States in the Great Basin Great Basin The Great Basin is the largest area of contiguous endorheic watersheds in North America and is noted for its arid conditions and Basin and Range topography that varies from the North American low point at Badwater Basin to the highest point of the contiguous United States, less than away at the...  region. Its range includes Idaho Idaho Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....  south of lat. 44° North, Utah west of long. 111° West, Arizona west and north of the Colorado River as well as the north rim of the Grand Canyon, the entire state of Nevada (excuding Esmeralda Esmeralda County, Nevada Esmeralda County is a county in the west of U.S. state of Nevada. Its county seat is Goldfield. Its 2000 census population was officially 971, making its population density 0.1045 inhabitants/km² , the second-lowest of any county-equivalent outside of Alaska. As of 2010, the population had... , Nye Nye County, Nevada -National protected areas:* Ash Meadows National Wildlife Refuge* Death Valley National Park * Humboldt-Toiyabe National Forest * Spring Mountains National Recreation Area -Demographics:...  and Clark Clark County, Nevada -Demographics:As of the census of 2000, there were 1,375,765 people, 512,253 households, and 339,693 families residing within the MSA. The racial makeup of the MSA was 71.6% White , 9.1% Black, 5.7% Asian, 0.8% American Indian and 12.8% of other or mixed race. 22.0% were Hispanic of any race...  counties), California east of the Sierra Nevada from Lower Klamath Lake Lower Klamath Lake Lower Klamath Lake is a lake in Siskiyou County, California, that currently serves to hold overflow water for irrigation. At one time it was connected to Upper Klamath Lake....  south to below Lake Mono, Oregon Oregon Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...  south and east of the line Upper Klamath Lake Upper Klamath Lake Upper Klamath Lake is a large, shallow freshwater lake east of the Cascade Range in south central Oregon in the United States. The largest freshwater body in Oregon, it is approximately 20 mi long and 8 mi wide and extends northwest from the city of Klamath Falls... -Fort Rock-Burns Burns, Oregon Burns is a city in and the county seat of Harney County, Oregon, United States. As of the 2010 census the population was 2,806.-History:Burns was established in the early 1880s and incorporated upon Harney county's creation in 1889... -Council Council, Idaho Council is a city in and the county seat of Adams County, Idaho, United States. The population was 839 at the 2010 census.-Geography:Council is located at ....  (Idaho).
C. o. oreganus	Holbrook John Edwards Holbrook John Edwards Holbrook American zoologist, herpetologist, physician, and naturalist, was born in Beaufort, South Carolina, the son of Silas Holbrook, a teacher, and Mary Edwards.... , 1840	Northern Pacific rattlesnake	From the Pacific slope in British Columbia British Columbia British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858... , Canada Canada Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean... , south through the United States to San Luis Obispo and Kern counties in California. This includes south-central British Columbia, Washington east of the Cascade Mountains, western Idaho from Coeur d'Alene Coeur d'Alene, Idaho Coeur d'Alene is the largest city and county seat of Kootenai County, Idaho, United States. It is the principal city of the Coeur d'Alene Metropolitan Statistical Area. Coeur d'Alene has the second largest metropolitan area in the state of Idaho. As of the 2010 census the population of Coeur...  south to near Council or Weiser Weiser, Idaho Weiser is a city in the rural western part of the U.S. state of Idaho and the county seat of Washington County. With its mild climate, the city supports farm, orchard, and livestock endeavors in the vicinity. The city sits at the confluence of the Weiser River with the great Snake River, which... , northern and western Oregon (excluding the Cascades), and California west of the Sierra Nevada. Also found on Morro Rock Morro Rock Morro Rock is a volcanic plug located just offshore from Morro Bay, California, at the entrance to Morro Bay Harbor. A causeway connects it with the shore, effectively making it a tied island. The area surrounding the base of Morro Rock can be visited. The rock is protected as the Morro Rock State... off the coast of San Luis Obispo county.