''Crotalus enyo'', commonly known as the Baja California rattlesnakeCampbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. . or Lower California rattlesnake,Klauber LM. 1997. Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. First published in 1956, 1972. University of California Press, Berkeley. . is a

pit viper The Crotalinae, commonly known as pit vipers,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . or pit adders, are a subfamily (biology), subfamily of Viperidae, vipers found in Asia and the ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

native to the coast and islands of northwestern

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

. Like all other pit vipers, it is

venomous Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

. Three

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

are currently recognized, including the

nominate subspecies In biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. ...

described here.

Description

The maximum reported length of this

is (Klauber, 1972). It is

sexually dimorphic Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

, with the males typically being larger than the females. The head is remarkably small and narrow, while the eyes are proportionately large.

Geographic range

In western

in the north, it is found in the Baja California Peninsula from around Río San Telmo on the west coast and from opposite Isla Angel de la Guarda on the gulf coast, south to

Cabo San Lucas Cabo San Lucas (, "Luke the Evangelist, Saint Luke Cape (geography), Cape"), also known simply as Cabo, is a Resort town, resort city at the southern tip of the Baja California peninsula, in the Mexican Political divisions of Mexico, state of Baja ...

. It is also found in the

Gulf of California The Gulf of California (), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Vermejo''), is a marginal sea of the Pacific Ocean that separates the Baja California peninsula from ...

on the islands of San Marcos, Carmen, San José, San Francisco, Partida del Sur, Espírita Santo and Cerralvo. Off the Pacific coast, it is also found on the island of San Margarita. The type locality is "

Cape San Lucas Cabo San Lucas (, "Saint Luke Cape"), also known simply as Cabo, is a resort city at the southern tip of the Baja California peninsula, in the Mexican state of Baja California Sur. As of the 2020 Census, the population of the city was 202,694.202 ...

Baja California Sur Baja California Sur, officially the Free and Sovereign State of Baja California Sur, is a state in Mexico. It is the 31st and last state to be admitted, in 1974. It is also the second least populated Mexican state and the ninth-largest state by ...

Habitat

It prefers

desert A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...

, but in the northwestern part of its range, it can be found in

chaparral Chaparral ( ) is a shrubland plant plant community, community found primarily in California, southern Oregon, and northern Baja California. It is shaped by a Mediterranean climate (mild wet winters and hot dry summers) and infrequent, high-intens ...

country, while in the cape region (Sierra de San Lázaro), it occurs in pine-oak and tropical deciduous forest. It can be found in rocky areas with arid thorn scrub and cacti, but sometimes also in sand dunes. It is often attracted to human habitation, where it has been found in piles of refuse.

Conservation status

This species is classified as Least Concern on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...

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

Feeding

Snakes of this species, regardless of their size, are known to eat small

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...

s, and

centipede Centipedes (from Neo-Latin , "hundred", and Latin , "foot") are predatory arthropods belonging to the class Chilopoda (Ancient Greek , ''kheilos'', "lip", and Neo-Latin suffix , "foot", describing the forcipules) of the subphylum Myriapoda, ...

s. This is in contrast to many other rattlesnake

that prey on lizards almost exclusively as juveniles, switching to mammals as adults. With ''C. enyo'', small snakes eat lizards more often than do large ones, and large snakes eat mammals more often than do small ones. Adults also prey on large centipedes of the genus ''

Scolopendra ''Scolopendra'', from Ancient Greek σκόλοψ (''skólops''), meaning "thorn", and ἔντερον (''énteron''), meaning "earthworm", is a species-rich genus of large tropical centipedes of the family Scolopendridae. Description The genus ...

''.

Reproduction

Captive specimens have produced litters of two to seven young. Newborn specimens with lengths of between have been mentioned. Grismer (2002) reported finding neonates in the wild between late July and mid October, which would indicate the

mates in the spring and gives birth in the summer or early fall.

Subspecies

Taxonomy

All three of the current

were recognized by Beaman and Grismer (1994) in their review, but they indicated ''C. e. furvus'' should not be considered a separate subspecies, and ''C. e. cerralvensis'' would best be considered a full species.

References

enyo In Greek mythology, Enyo (; ) is a war-goddess, frequently associated with the war-god Ares. The Romans identified her with Bellona. Enyo is also the name of one of the Graeae, one of three grey-haired sisters who share an eye and a tooth. ...

Endemic reptiles of Mexico Fauna of Gulf of California islands Endemic fauna of the Baja California Peninsula Reptiles of Mexico Reptiles described in 1861 Taxa named by Edward Drinker Cope