Overview
The Mexican West Coast Rattlesnake, Crotalus basiliscus, is a venomous pit viper native to the western Pacific slope of Mexico. Common names include Mexican Green Rattler and Mexican West Coast Green Rattlesnake. The scientific name alludes to the Greek word basiliskos, associated with 'king' because of the species' relatively large size. No subspecies of Crotalus basiliscus are currently recognized. For basic taxonomic and identification resources see species information.
Identification and physical characteristics
This species is notable for a greenish to olive ground color that helps it blend into vegetation, although tones may range to brown or gray in some individuals. It has the characteristic triangular head of pit vipers, a distinctive rattle at the tail tip, and heat-sensing facial pits between the nostrils and eyes. Scalation and patterning vary with age and locality; younger snakes often show bolder markings that fade with maturity. Males and females may differ in size and tail length, with adults among the larger rattlesnake species of the region.
- Triangular head and keeled dorsal scales
- Greenish-olive coloration, variable patterning
- Heat-sensing pits characteristic of pit vipers
- Terminal rattle used in warning displays
Distribution and habitat
C. basiliscus occurs along Mexico’s Pacific slope in a range of lowland to mid-elevation habitats. It inhabits tropical deciduous forest, thorn scrub, rocky hillsides and edges of cultivated areas where cover and prey are available. The snake’s coloration and behavior make it well adapted to ambush hunting among leaf litter, shrubs and low branches.
Behavior, diet and reproduction
Primarily an ambush predator, the Mexican West Coast Rattlesnake feeds on small mammals, birds and terrestrial lizards. Activity patterns are influenced by temperature and season: snakes may be crepuscular or nocturnal during hot months and more diurnal when conditions are cooler. As with other pit vipers, reproduction is viviparous: females give birth to live young rather than laying eggs.
Venom and medical importance
The venom of Crotalus basiliscus is medically significant and can cause severe local tissue damage, pain and systemic effects if untreated. Envenomations require prompt medical assessment and, when indicated, administration of appropriate antivenom and supportive care. Because severity varies with bite circumstances and individual response, avoidance and public education are the best measures to reduce human-snake conflict.
Conservation and notable facts
Threats to the species include habitat alteration, persecution, and road mortality. Its conservation status depends on local population trends and habitat integrity; protective measures emphasize habitat preservation and reducing unnecessary killing. Notable among rattlesnakes, the Mexican West Coast Rattlesnake’s greenish coloration and relatively large size make it a distinctive member of Mexico’s snake fauna. For more identification details and regional data consult further resources.