Trimorphodon lambda - Sonoran Lyresnake

Mildly Venomous

One of the larger rear-fanged snakes, but considered harmless to humans, but handle with caution, as some people have had unpleasant reactions to this snake's bite.

Size

Trimorphodon have been recorded from 18 - 47 3/4 inches in length (46 - 121 cm). Most snakes encountered are 24 - 36 inches long (61 - 91 cm).

Appearance

A slender snake with a broad head well-differentiated from the slim neck. Coloring closely matches a snake's rocky habitat, from gray to light brown. There are usually about 28 large dorsal blotches with light edges and a pale crossbar in the center, and smaller irregular blotches on the lower sides. A lyre-shaped marking is present on top of the head. The pupils are vertical, like those of a cat. The underside is off-white or yellowish with dark spots. The anal plate is usually divided.

Behavior

Nocturnal, active in very dry conditions as well as during rains. Terrestrial, and good climbers. This snake often searches rock crevices for prey. It can be found during the day inside crevices in large rock outcrops, as well as crossing desert roads at night.

Diet

Primarily lizards, but also known to eat small mammals, nestling birds, and snakes.

Reproduction

Not well known. Lyre snakes apparently originated in the tropics, where breeding is year round, and the northern races may have retained this capability.

Range

In California, found only in the southeast along the Colorado River from approximately the Riverside/Imperial County line, north into San Bernardino County and the Nevada border. Ranges north into southern Nevada and extreme southwest Utah, through Arizona and extreme southwest New Mexico, south into Sonora and Sinaloa, Mexico.

Habitat

Associated primarily with rocky desert locations, but found in rockless areas, also.

Taxonomic Notes

Devitt et al, in a 2008 paper*, recommended that the subspecies of Trimorphodon biscutatus - lambda, lyrophanes, and vilkinsonii, be recognized as distinct species - Trimorphodon lambda, Trimorphodon lyrophanes, and Trimorphodon vilkinsonii.

*Thomas J. Devitt, Travis J. LaDuc & Jimmy A. McGuire. (2008. The Trimorphodon biscutatus (Squamata: Colubridae) Species Complex Revisited: A Multivariate Statistical Analysis of Geographic Variation. Copeia. 2008(2): 370-387) Conservation Issues (Conservation Status) None.