Coronado Skink, Plestiodon skiltonianus interparietalis

Coronado Skink, Plestiodon skiltonianus interparietalis, Juvenile. Skink collected in a residential community in San Diego Califonria, April 2023. Identification courtesy of Gary Nafis, Californiaherps.com.

The Coronado Skink, Plestiodon skiltonianus interparietalis, is a member of the Scincidae family of Skinks. The Scincidae family consists of thirteen hundred members placed in one hundred genera. There are forty-one known species in the Plestiodon genus. They are one of three recognized subspecies of the Western Skink, Plestiodon skiltonianus. The Coronado Skink is known in Mexico as Eslizón de Coronado.

Coronado Skinks are small in size with a slim body, small head, thick neck, and small legs. Their smooth, shiny body is covered with cycloid scales. They possess a distinct striping pattern. A wide, dark brown stripe, edged with black, extends dorsally from their nose to their tail along the center of their back. This stripe is bordered by two pale stripes which extend dorsally from their nose, over their eyes, to their tail. Two more dark stripes extend laterally across their eyes, along their sides, and along much of their tail. Two more pale stripes extend below these dark lateral stripes. Their underside is pale or gray in color. The stripes on Juvenile Coronado Skinks are more highly contrasted and their tail is bright blue. Younger adults often retain some of this bright blue coloring on their tails while older adults typically have gray or dull blue tails. The Coronado Skink’s blue tail is occasionally mistaken for a small blue snake and distracts predators from the main body of the lizard. Their tail is easily broken off and writhes back and forth on the ground, distracting predators and allowing them to escape. The lizard will then grow a new tail. During breeding season, adults develop a reddish orange coloring on the side of their head, chin, along their tail, and sometimes on their sides. They typically measure between 5.4 cm (2.1 inches) and 8.6 cm (3.4 inches) from snout to vent and 19 cm (7.5 inches) in total length.

Coronado Skinks are diurnal and highly secretive. They can occasionally be found foraging in leaf litter and dense vegetation, preying upon insects and small invertebrates including spiders, crickets, beetles, moths, and grasshoppers. They are more commonly found underneath bark and surface objects, especially rocks, where they live in extensive burrows that are several times their own body length. During cold weather, they become inactive. Mating likely occurs in the spring when temperatures warm up and Coronado Skinks become active. Females lay 2 to 10 eggs in June and early July. Eggs are typically laid in burrows or areas excavated by the female under rocks and stones. Females guard their eggs until they hatch in late July and August. Female Coronado Skinks will defend their nests from predators, repair their nests, and even bask in the sun and return to their nest to provide additional heat. This form of parental care is rarely visible in lizards.

Coronado Skinks may be confused with Gilbert’s Skink, Plestiodon gilberti (stripes on the sides do not extend past the rear legs and onto the tail; eight supralabial scales).

From a conservation perspective, the IUCN currently includes all Western Skink species under the same listing so the exact status of this subspecies is unclear. The Western Skink is considered to be of Least Concern with a wide distribution, a strong tolerance of a broad range of habitats, and populations. No major threats have been identified for this species.