Lichanura trivirgata - Rosy Boa

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.)