Common English names: Santa Catalina Rattlesnake, Santa Catalina Island Rattlesnake

Crotalus catalinensis 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...

 endemic

Endemic (ecology)

Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...

 to Isla Santa Catalina located in the Gulf of California

Gulf of California

The Gulf of California is a body of water that separates the Baja California Peninsula from the Mexican mainland...

 just off the eastern coast of the state 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...

, 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...

. No subspecies are currently recognized. A relatively small and slender species, its most distinctive characteristic is that it lacks a rattle.

Description

This species is relatively slender and stunted, growing to a maximum of 73.1 cm in length.

The most distinctive feature about this species of rattlesnake is that it has no rattle at all. The base of the tail, referred to as the "button", has degenerated to such an extent that the rattle immediately falls off with each shed instead of forming a new segment, as it does in other species of rattlesnake. This is widely believed to be a localized adaptation for hunting birds.

There are two distinct color variations. The predominant variant has a light cream colored base, with red

Red

Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 630–740 nm. Longer wavelengths than this are called infrared , and cannot be seen by the naked eye...

dish-brown

Brown

Brown is a color term, denoting a range of composite colors produced by a mixture of orange, red, rose, or yellow with black or gray. The term is from Old English brún, in origin for any dusky or dark shade of color....

 blotching down the back, and black and white banding around the tail. The other variant has a much lighter, ash grey

Grey

Grey or gray is an achromatic or neutral color.Complementary colors are defined to mix to grey, either additively or subtractively, and many color models place complements opposite each other in a color wheel. To produce grey in RGB displays, the R, G, and B primary light sources are combined in...

 color, with darker grey blotching. The banding around the tail is still present.

Geographic range

Found only in western 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 Isla Santa Catalina in the Gulf of California

Gulf of California

The Gulf of California is a body of water that separates the Baja California Peninsula from the Mexican mainland...

 off the coast of southern 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...

. This island is also the type locality for the 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...

.

Conservation status

This species is classified as Critically Endangered (CR) 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...

 with the following criteria: B1ab(v) (v3.1, 2001). This means that the best available evidence indicates that it is considered to be facing an extremely high risk of extinction in the wild because its geographic range is estimated to be less than 100 km², it exists at only a single location, and a continuing decline has been observed, inferred or projected in the number of mature individuals. Year assessed: 2007.

It is threatened due to collecting and the introduction of alien predator species, such as feral cats.

Habitat

The habitat on Santa Catalina Island consists of Gulf Coast Desert plants. This snake is often found on the western side of the island within the many arroyo

Arroyo (creek)

An arroyo , a Spanish word translated as brook, and also called a wash is usually a dry creek or stream bed—gulch that temporarily or seasonally fills and flows after sufficient rain. Wadi is a similar term in Africa. In Spain, a rambla has a similar meaning to arroyo.-Types and processes:Arroyos...

s.

Behavior

While most members of this genus are almost entirely terrestrial due to their heavy body structure, this species' small size makes it a swift and skillful climber. The hypothesis is that the lack of a rattle enables these snakes to approach fast moving prey, such as roosting bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s, without alerting it to their presence.

Feeding

This species feeds mainly on birds. Unlike most rattlesnakes, this species will often hang onto its prey when it strikes.

Taxonomy

Klauber

Klauber

Klauber:* Abraham Klauber * Marcy Klauber * Laurence M. Klauber , an American herpetologist...

 (1972) suggests that this species is closely related to C. scutulatus

Crotalus scutulatus

Crotalus scutulatus is a venomous pitviper species found in the deserts of the southwestern United States and central Mexico. It is perhaps best known for its potent neurotoxic venom...

. However, a later study by Murphy and Crabtree (1985) used allozyme

Allozyme

Variant forms of an enzyme that are coded by different alleles at the same locus are called allozymes. These are opposed to isozymes, which are enzymes that perform the same function, but which are coded by genes located at different loci....

 data to conclude that its shares its most recent ancestor with C. ruber

Crotalus ruber

Crotalus ruber is a venomous pitviper species found in southwestern California in the United States and Baja California in Mexico. Three subspecies are currently recognized, including the nominate subspecies described here.-Description:...

. Most of the morphological, biogeographic and biochemical data suggests the same.