Variable Sandsnake, Chilomeniscus stramineus

Variable Sandsnake, Chilomeniscus straminenus. This snake was collected from within damp moist sand in a drainage canal in the greater San José del Cabo area, Baja California Sur. Length: 25 cm (10.0 inches).

Variable Sandsnake, Chilomeniscus straminenus. Snake collected from a residential property in the greater Los Cabos area, Baja California Sur, June 2019. Length: 25 cm (10.0 inches).

Variable Sandsnake, Chilomeniscus straminenus. Snake collected within a residential property in the greater Los Barriles area, Baja California Sur, December 2017. Length: 25 cm (10.0 inches). Collection courtesy of Mike Rousseau, Maple Ridge, British Columbia, Canada. First two photographs courtesy of Brad Murakami, Surrey, British Columbia, Canada. Third photo courtesy of Eunice Rousseau, Maple Ridge, British Columbia, Canada.

Variable Sandsnake, Chilomeniscus straminenus. Photograph taken within a residential community in the greater Alamos area, Alamos, Sonora, December 2018. Photograph and identification courtesy of David F Smith, Alamos, Sonora.

The Variable Sandsnake, Chilomeniscus stramineus,  is a member of the Colubridae family of North American Racers, Coachwhips, and Whipsnakes. The Colubridae family comprises two-thirds of the world’s snake population with approximately two-thousand species placed in two-hundred and fifty-seven genera. Many Colubrids are classified as venomous but very few are considered to be dangerous to humans. There are two species in the Chilomeniscus Genus of burrowing snakes. Until recently, Chilomeniscus stramineus was divided into two species with banded individuals referred to as Chilomeniscus cinctus. However, all mainland morphs are now considered synonymous. The Variable Sandsnake is known in Mexico as Culebra-arenera Manchada.

Variable Sandsnakes are small and stout and their head is continuous with their thick neck. They have small upturned eyes with round pupils, valves to block their nasal passages, and a flat and wedge-like protruding light gray snout. Their jaws are sunken and their belly is concave. They are covered in smooth shiny scales which, combined with their other traits, are useful for burrowing in fine gravel and sand. The Variable Sandsnake is cream, yellowish, orange, or red-orange in color dorsally. Their ventral surface is lighter in color. They have two morphologies; one without banding, and one with twenty-four to forty-eight broad black bands that extend to or onto their ventral surface. On the coast from Punta Lobos south to Estro Tastiota in Mexico, some individuals may have several dorsal lines of dark dots, broken stripes, or speckling. All of these forms occur together within the banded morph. Sexual dimorphism is displayed with males growing slightly longer tails, possessing more subcaudal scales, and displaying keeled dorsal scales just anterior to their vent. In their banded form, males have five to nine dark bands on their tails, while females have three to five bands on their tails. Adults reach a snout to vent length between 18 cm (7.1 inches) an 28 cm (11.0 inches).

Variable Sandsnakes are nocturnal and become active during heavy rains, seldom surfacing during the day. They are excellent at burrowing and can move quickly through loose sand. During hot summer nights, they are commonly found on desert roads. Mating likely takes place from January to June, and clutches of two to three eggs are laid through July and August. However, not all females produce eggs each year. In southern Sonora, this species may have an extended breeding season. The Variable Sandsnake is an active forager, seeking prey on the surface and underground. They consume invertebrates such as Centipedes, Cockroaches, and Ant pupae. Slightly grooved teeth in the rear of their upper jaw may be used to deliver toxins from a Duvernoy’s gland to their prey. Although, these toxins do not cause serious illness or injury in most humans. They are likely preyed upon by large Birds, Snakes, and Mammals. The Variable Sandsnake is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, and habitat use.

The Variable Sandsnake may be confused with the Western Shovel-nosed Snake, Chionactis occipitalis, due to their similar appearances and overlapping ranges. These species can be differentiated visually. The Western Shovel-nosed Snake has internasal scales that touch, and red to red-orange bands that are separated from the black bands with a white, cream, or yellowish band.

From a conservation perspective, the Variable Sandsnake is currently considered to be of Least Concern due to its wide distribution and presumed large population size. No major threats have been identified for this species.