Crotalus catalinensis

Common names: Santa Catalina rattlesnake,^[2] Santa Catalina Island rattlesnake, ^[3] more.

Crotalus catalinensis is a venomous pitviper endemic to Isla Santa Catalina, Mexico. No subspecies are currently recognized.^[4] A relatively small and slender species, its most distinctive characteristic is that it lacks a rattle.^[2]

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Description

This species is relatively slender and stunted, growing to a maximum of 73.1 cm in length.^[2]

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.^[3]

There are two distinct color variations. The predominant variant has a light cream colored base, with reddish-brown blotching down the back, and black and white banding around the tail. The other variant has a much lighter, ash grey color, with darker grey blotching. The banding around the tail is still present.

Common names

Santa Catalina rattlesnake,^[2] Santa Catalina Island rattlesnake, Santa Catalina Island rattleless rattlesnake,^[3] rattleless rattlesnake, víbora-cascabel muda (Spanish).^[4]

Geographic range

Found only in western Mexico on Isla Santa Catalina in the Gulf of California off the coast of southern Baja California. This island is also the type locality for the species.^[1]

Conservation status

This species is classified as ... (CR) on the IUCN Red List of Threatened Species with the following criteria: B1ab(v) (v3.1, 2001).^[5] 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.^[6]

It is threatened due to collecting and the introduction of alien predator species, such as feral cats.^[3]

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 arroyos.^[3]

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 theory is that the lack of a rattle enables these snakes to approach fast moving prey, such as roosting birds, without alerting it to their presence.^[3]

Feeding

This species feeds mainly on birds. Unlike most rattlesnakes, this species will often hang onto its prey when it strikes.^[3]

Taxonomy

Klauber (1972) suggests that this species is closely related to C. scutulatus. However, a later study by Murphy and Crabtree (1985) used allozyme data to conclude that its shares its most recent ancestor with C. ruber. Most of the morphological, biogeographic and biochemical data suggests the same.^[2]

See also

• List of crotaline species and subspecies
• Crotalus by common name
• Crotalus by taxonomic synonyms
• Crotalinae by common name
• Crotalinae by taxonomic synonyms
• Snakebite

References

Further reading