San Diego Natural History Museum--Your Nature ConnectionSDNHM Field Guide
Coastal Rosy Boa, photographed by Jim Melli

Lichanura trivirgata
Rosy Boa

BOIDAE

Lichan- is from the Greek lichanos, meaning the fore-finger and -oura meaning tail -- perhaps a reference to the Rosy Boa's blunt tail. The name trivirgata means three-stripes.

Description

The Rosy Boa is one of the smallest members of the Boa family, and rarely grows much larger than 3 feet (1 meter) in length. It has a heavy-bodied build, a short, blunt tail and small head. Its eyes have elliptical pupils like those of a cat.

This species usually has a pattern of three, poorly defined, lengthwise stripes -- one central and two lateral -- on a lighter ground. Coloration includes shades of gray, tan, or reddish brown. Individuals from the coast and foothills may be, on occasion, nearly a uniform gray or brown color, with less defined stripes. Individuals from the desert tend to exhibit a more distinct pattern of stripes.

Subspecies: There have been as many as five subspecies recognized: the Mexican Rosy Boa (L. t. trivirgata); the Desert Rosy Boa (L. t. gracia); the Coastal Rosy Boa (L. t. roseofusca); the Baja California Rosy Boa (L. t. saslowi); and the Cedros Island Rosy Boa (L. t. bostici). All appear to intergrade widely and their different color patterns appear to correspond to the ecogeography of the areas they are found.

Range and Habitat

The Rosy Boa ranges from southern California and western Arizona in the United States, southward to Baja California and western Sonora in Mexico. This species inhabits rocky areas in coastal sage scrub, chaparral, and desert environments.

Natural History

This snake is usually most active at dusk and at night. In early spring, or in cooler coastal areas, it may be active during the day. Rosy Boas feed largely on warm-blooded prey, such as small mammals and birds. Like its larger relatives, it kills its prey by constriction.

Sometimes, when attacked by a predator, the Rosy Boa rolls up into a ball, keeping its head in the center. It then releases a foul smelling musk from glands near the base of its tail. Its blunt tail may act to divert a predator from attacking its head which remains buried in its coils. This habit of coiling around its own head appears to make it difficult for predators, such as birds of prey, to kill or even handle a Rosy Boa. Older individuals sometime carry evidence of attacks, such as docked tails and scars on their bodies.

The Rosy Boa is the most docile snake within our region.

The eggs of the Rosy Boa develop in the the snake's body and the young are born alive.

Did you know...

Like other members of the Boa family, the Rosy Boa has two curious claw-like spurs near its vent, attached to bones inside its body. These anal spurs are vestigial hind legs inherited from their lizard ancestors.

Conservation Status

This species is currently a Federal Special Concern species (FSC). It is also protected from international trade by CITES. Because of this species notoriety in the pet trade, it is highly sought after by collectors.

Because of widespread negative attitudes towards snakes, very few conservation programs, worldwide, have been created. A much higher percentage of snakes are threatened with extinction than is currently recognized. Therefore, snakes are particularly susceptible to being overlooked by conservation-minded biologists.