Ring-necked Snake, Diadophis punctatus

Ring-necked Snake, Diadophis punctatus. Snake photographed in rural Villanueva, New Mexico, October 2024. Length: 25 cm (10 inches). Collection, photograph and identification courtesy of Dr. Jake Turin, Albuquerque, New Mexico.

Ring-necked Snake, Diadophis punctatus. Snake photographed in rural Las Vegas, New Mexico, July 2020. Length: 33 cm (13 inches). Collection, photograph and identification courtesy of Dr. Jake Turin, Albuquerque, New Mexico.

The Ring-necked Snake, Diadophis punctatus, 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 one thousand seven hundred sixty species placed in two hundred forty-nine genera. Many Colubrids are classified as venomous but very few are considered to be dangerous to humans. There are four species in the Diadophis Genus and 12 recognized sub-species of Diadophis punctatus. Note: there is significant on-going work within the scientific community reclassifying the Colubridae Family which includes moving this species to the Disadidae Family. This is not recognized by all. The Ring-necked Snake is also known as Key-necked Snake and the Ringneck Snake and in Mexico as Culebras de Collar.

The adult Ring-necked Snakes are 21 cm (8.0 inches) to 36 cm (14 inches) in length. They are small and slender in stature with a black or slate gray body and a yellowish ring across the neck, which may be incomplete or missing, and crescent-shaped black spots along the margins. The head is normally slightly darker than the body with round pupils. The belly and underside of the tail are bright yellow, orange, or red. The juvenile are similarly colored as the adults. They have smooth scales with 15 to 17 rows mid-body. They are sexually dimorphic with males having small tubercles on their scales just anterior of the vent which are absent in females; the females are larger and proportionally shorter tails than the males.

The Ring-necked Snake is a secretive, crepuscular, nocturnal, predator that is primarily terrestrial but can be found in shrubs and trees on occasion. They feed primarily on earthworms, frogs, insects, small lizards, salamanders, snakes, slugs, and toads. These snakes are not constrictors. Larger prey is slowly immobilized using a mildly toxic venom that is delivered by two slightly elongated teeth at the rear of the mouth. Smaller prey is quickly swallowed alive. During the day they primarily remain hidden underground among rocks and vegetation. In the winter when temperatures are low, they brumate to conserve energy. The have life spans in excess of 10 years.

The Ring-necked Snake has a unique defense mechanism winding their body into a corkscrew exposing its bright colored belly as a defense mechanism which indicates to most predators that they are highly venomous; this “false warning” coloration is a form of mimicry, a survival adaptation in which a non-venomous species has evolved brighter coloration, similar to truly venomous species, and used it to their advantage. They also that the ability to release a foul-smelling musk.

The Ring-necked Snake are found with the interior of Mexico south to the Transvolcano Belt in Jalisco and San Luis Potosi in the central mainland and within the northern portions of Baja California including Islas Todos Santos and San Martin in the Pacific Ocean. The Mexican populations diverged first in the phylogenetic lineage of the subspecies of ringneck species. They are found in a wide variety of habitats but most abundant in moist wooded areas, floodplains, hardwood forests, wetland edges, and in the mountains, often beneath rocks in more open moist terrain. During daylight hours, this snake generally hides underground, in or under logs, or under rocks, stumps or other surface cover. They utilize basking in the sun to increase body temperatures. They are highly secretive but can be found in colonies of more than 100 individuals. They are not found at elevations above 2,200 m (7,200 feet). They are most active between March and October.

The Ring-necked Snake is a straightforward identification that cannot be confused with any other species. They are similar to the Black-headed Snakes of the Tantilla Genus, the Chihuahuan Black-headed Snake, Tantilla wilcoxi, Smith’s Black-headed Snake, Tantilla hobartsmithi, and the Yaqui Black-headed Snake, Tantilla yaquia.

From a Conservation perspective the Ring-necked Snake is currently considered to be of Least Concern with very large far-ranging populations without major threats. They play an important ecological role as both predators and prey. They are prone to loss of habitat due to human development. They are non-venomous and not dangerous to pets or people.