A Guide to the Amphibians
and Reptiles of California

Lichanura trivirgata - Rosy Boa

(Also known as Coastal Rosy Boa in California and Mexican Rosy Boa elsewhere)

Click on a picture for a larger view

Range in California: Green

Red: Northern Three-lined Boa

Adult male, San Diego County, Otay Lake locality.

Adult male, San Diego County,
Otay Lake locality.

Unstriped "unicolor" Adult, San Diego County, Barret Lakes locality. © Gary Nafis Specimen courtesy of Tim Burkhardt

Unstriped "unicolor" Adult, San Diego County. © Gary Nafis Specimen courtesy of Jim Melli

Unicolor adult, San Diego County
© Brian Hinds

Habitat

Habitat, San Diego County

Description

Nonvenomous

Considered harmless to humans.

Size

Adults 17 - 44 inches long (43 - 112 cm) but generally under 36 inches. The largest Rosy Boa subspecies. Hatchlings are 10 - 14 inches long.

Appearance

A heavy-bodied snake with smooth shiny scales and a blunt, but tapered tail. The head is only a little wider than the neck. Pupils are vertical.

There are three poorly-defined irregular dark stripes, brown, reddish-brown, orange or rust in color, running lengthwise on the back and sides with a gray, olive-gray, bluish-gray or brownish ground color inbetween. Flecks of the stripe color are usually present in the ground color (unlike the Coastal Rosy Boa, where the stripes are more well-defined. Snakes with more contrasting even-edged stripes are associated with drier habitats.) The belly is predominantly dark - often bluish to bluish-gray with dark flecks. A "unicolor" phase without dark stripes is found in southern San Diego County and Baja Californi, where most or all of the dark markings are blended into the body color which can be orange, yellowish, or nearly purple in color.

Males have small spurs on each side of the vent which are vestigial hind limbs.

Rosy boas of all subspecies have been common pet snakes for many years. Breeders have produced new color morphs and, in order to promote regional variations in appearance, they have also designated sometimes confusing locality-specific names such as Verbenia, Corn Springs, Whitewater, Pioneertown, Long Canyon, Mojave, San Gabriel, Lake Elsinore, Hemet, Unicolor, Anza-Borrego, Harquahala, Bagdad, Baja Cape, San Felipe, Catavina, and Bay of LA, among others.

Behavior

Primarily active at dawn, dusk, and at night, rarely in daylight, but may be active in the morning, especially in cool weather. In the hottest and coldest months of the year, remains inactive in burrows or under surface debris. A good climber.

Sometimes rolls the body into a ball and hides the head when alarmed.

Diet

Eats rodents, small birds, lizards, small snakes, and amphibians. Kills prey by constriction.

Reproduction

Live-bearing; young are born October - November.

Range

Occurs in extreme southern California within the Tijuana River and Otay watersheds, southward throughout the Baja California peninsula, and on the mainland of northwestern Mexico in the state of Sonora. In Arizona it occurs throughout isolated mountain ranges south of the Gila River in Maricopa, Pima, and Pinal Counties.

Habitat

Inhabits arid scrublands, semi-arid shrublands, rocky shrublands, rocky deserts, canyons, and other rocky areas. Appears to be common in riparian areas, but does not require permanent water.

Taxonomic Notes

Rosy boa taxonomy can be confusing. The generic name Lichanura has been challenged, with some taxonomists placing the snake in the genus Charina, along with the Rubber Boas. The three traditional subspecies, gracia, roseofusca, and trivirgata, have also been challenged, with gracia and roseofusca placed into the subspecies myriolepis, and the Arizona populations into arizonense.

Since most Rosy Boas do not have the rosy ventral coloring which gives the snake its name, Robert Stebbins (Stebbins, 2003) has suggested using the common name Three Lined Boa, which was given the snake by the original describer (E. D. Cope, 1861.)

A 2007 study by Wood, Fisher and Reeder * found discrepencies between mtDNA and currently recognized subspecies of Lichanura trivirgata leading them to recognize two evolutionary species - Lichanura orcutti, and Lichanura trivirgata.
They describe the ranges of these two species in this way:

L. orcutti

"Distribution. North of the US–Mexico border within San Diego, County in California along the coastal Peninsular Ranges, northward into the Mojave Desert and eastward in the Sonoran Desert of California and Arizona. In Arizona this species inhabits areas north of the Gila River, except for individuals inhabiting the Gila Mountains."

(This species consists of L. t. roseofusca (excluding extreme southern San Diego County boas) and L. t. gracia, including the "Arizona Rosy Boa" phase.)

L. trivirgata

"Distribution. Extreme southern San Diego County, California within the Tijuana River and Otay watersheds, southward throughout the Baja California peninsula, and northwestern Mexico in the state of Sonora. In Arizona it can be found throughout isolated mountain ranges south of the Gila River in Maricopa, Pima, and Pinal Counties."

(This species consists of the extreme southern San Diego County Lichanura (including the "Unicolor" boas), the Mid-Baja " L. t. saslowi" boas, and the Mexican Rosy Boa - L. t. trivirgata.)

Some San Diego County locations for this species are Otay Valley, Hollenbeck Canyon, Barrett Junctiion, Honey Springs, Skyline Truck Trail, and Marron Valley.

These findings contradict many years of accepted Rosy Boa taxonomy and the established pattern classes used by a large group of Rosy Boa hobbyists who have resisted the changes.

Conservation Issues (Conservation Status)

Listed as a sensitive species by the USFS and the BLM (under the scientific name Charina trivirgata.)

Taxonomy
Family	Boidae	Boas and Pythons
Genus	Lichanura	Rosy Boas
Species	trivirgata	Rosy Boa
Original Description
Charina trivirgata - Cope, 1861 - Proc. Acad. Nat. Sci. Philadelphia, Vol. 13, p. 304 from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
Meaning of the Scientific Name
Lichanura - Greek - lichanos - forefinger, and oura tail - possibly refers to the body form or the stumpy tail (that could be said to look like a finger) trivirgata - Latin - tri - three, and virgata - striped - refers to the color pattern from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
Alternate Names
Lichanura trivirgata roseofusca - Coastal Rosy Boa Lichanura tirvirgata saslowi - Baja Rosy Boa Lichanura trivirgata myriolepis - Baja Rosy Boa Lichanura trivirgata trivirgata - Mexican Rosy Boa
Related or Similar California Snakes
L. orcutti - Northern Three-lined Boa (Desert Rosy Boa) C. bottae - Northern Rubber Boa C. umbratica - Southern Rubber Boa
More Information and References
Natureserve Explorer California Dept. of Fish and Game LocalityRosys.com Borderboas.com Wood, Dustin A., Robert N. Fisher, and Tod W. Reeder. Novel patterns of historical isolation, dispersal, and secondary contact across Baja California in the Rosy Boa (Lichanura trivirgata). Molecular Phylogenetics and Evolution 46 (2008) 484–502. December 2007. Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003. Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992. Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998. Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Snakes of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009. Bartlett, R.D. , & Alan Tennant. Snakes of North America - Western Region. Gulf Publishing Co., 2000. Brown, Philip R. A Field Guide to Snakes of California. Gulf Publishing Co., 1997. Ernst, Carl H., Evelyn M. Ernst, & Robert M. Corker. Snakes of the United States and Canada. Smithsonian Institution Press, 2003. Wright, Albert Hazen & Anna Allen Wright. Handbook of Snakes of the United States and Canada. Cornell University Press.

Conservation Status
The following status listings come from the Special Animals List which is published several times each year by the California Department of Fish and Game. Notes from the 1/11 Special Animals List: Charina trivirgata rosy boa 1) The Forest Service "Sensitive" designation refers only to the subspecies roseofusca. 2) The taxonomy of this species is in flux. The name Lichanura trivirgata is a synonym. Some sources list several subspecies while others don't recognize any subspecies.
Organization	Status Listing
U.S. Endangered Species Act (ESA)	None
California Endangered Species Act (CESA)	None
California Department of Fish and Game	None
Bureau of Land Management	BLM:S	Sensitive
USDA Forest Service	USFS:S	Sensitive
Natureserve Global Conservation Status Ranks	G4G5 S3S4	Apparently Secure
World Conservation Union - IUCN Red List	LC	Least Concern

Return to the Top