[vc_row][vc_column][vc_column_text]

Mountain Skink (Plestiodon callicephalus)

[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”178″ img_size=”large” alignment=”center” style=”vc_box_rounded”][vc_column_text]Mountain Skink, Pajarito Mtns, AZ. Photo by Jim Rorabaugh[/vc_column_text][/vc_column][vc_column width=”1/2″][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”1942″ img_size=”medium” alignment=”center” onclick=”img_link_large”][vc_column_text]Mountain Skink, Sierra Aconchi, Sonora, MX. Photo by Jim Rorabaugh[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column width=”1/6″][/vc_column][vc_column width=”2/3″][vc_column_text]

Description

Editor’s Note: The Mountain Skink is now in the genus Plestiodon.

Skinks (family Scincidae) are lizards characterized by smooth, shiny cycloid scales that are underlain by osteoderms, or plate-like bony deposits in the skin (Pough et al. 2001). Because of their hard, rounded bodies, skinks are presumably difficult prey for many predators to handle. Of the approximately 1100 species of skinks found worldwide (Pough et al. 2001), Arizona is home to only five. The mountain skink (Eumeces callicephalus) occurs throughout northern Mexico, but is found in the United States only in five “sky Island” mountain ranges in extreme southeastern Arizona and southwestern New Mexico (Stebbins 2003). Due to its limited range in the U.S., very little is known about ecology, behavior, and habitat choice of the mountain skink.

The taxonomy and nomenclature of the mountain skink is somewhat vague. Some authors (e.g. Lieb 1990) refer to the species as a subspecies of the four-lined skink (E. tetragrammus), which occurs throughout Mexico and southern Texas. However, it is considered by Crother (2002) as a separate species based on Tanner (1987) because it is allopatric (geographically isolated) from the four-lined skink and morphologically distinct.

Mountain skinks are a medium-sized species of Eumeces with a maximum SVL of 76 mm (Lieb 1990). Their dorsal coloration is olive-gray with a distinct dark lateral band, 2-3 scales wide, which extends from their neck to their groin (Degenhardt et al. 1996). Adult males have bright red lips (Degenhardt et al. 1996). Most distinguishing is a Y-shaped light line on the head. The name “callicephalus” is a Greek word meaning “beautiful head”, which probably refers to this lyre-shaped mark (Degenhardt et al. 1996). Like many skinks, juveniles have bright-blue tails. However, in mountain skinks the blue tail color remains in adulthood but is less vivid (Stebbins 2003). Mountain skinks will easily lose their tails if caught and are capable of tail regeneration.

In (or immediately joining) the 100-mile circle, mountain skinks are known from the Baboquivari, Huachuca, Pajarito, and Santa Rita mountains. In the U.S., mountain skinks typically inhabit oak and pine habitats in rocky areas in the mountains. Other lizard species also associated with these mountain habitats include the Madrean alligator lizard ( Elgaria kingii ) and the mountain spiny lizard (Sceloporus jarrovii). In these mountain habitats, mountain skinks are found up to up to approximately 1970m (6500 ft.) in elevation. However, in Mexico they range down to the coastal plains (Stebbins 2003). Multiple observations of reproductive activity suggest a clutch of 3-6 eggs (Degenhardt et al. 1996). However, Taylor (1985) reported an individual from southern Arizona giving birth to live young. Mountain skinks presumably feed on insects and spiders.

Ground cover in our personal observations includes large boulders and a significant amount of accumulated leaf litter. We often find mountain skinks close to a water source (within 10 meters). We have found skinks active May-September and, like most species of skinks, they are diurnal. We typically encounter them during mid-day (late morning to early-afternoon). A captive mountain skink in our care also exhibited diurnal behavior and by mid-afternoon, it would retreat under cover and showed no crepuscular or nocturnal activity.

Mountain skinks are very cryptic in the brown and gold colors of oak leaf litter and can be extremely difficult to find. When disturbed, most skinks retreat quickly into boulder piles or leaf litter and disappear. In the cases where we did not find skinks under cover, we usually first detected them audibly. The sound of their foraging and fleeing behavior is distinct from other lizards in the area. Mountain skinks make short, abrupt movements that cause sharp cracking sounds in dry leaf litter. Our observations are consistent with others made for this species and E. tetragrammus in that they are diurnal and secretive, and that they avoid open habitats and seldom venture from shelter (Degenhardt et al. 1996).

Literature Cited

Crother, B.I. 2000. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Society for the study of amphibians and reptiles, herpetological circular no. 29:82pp.

Degenhardt, W.G., C.W. Painter, and A.H. Price. 1996. Amphibians and reptiles of New Mexico. University of New Mexico Press, Albuquerque, New Mexico. 431pp.

Lieb, C.S. 1990. Eumeces tetragrammus. Catalogue of American Amphibians and Reptiles: 492.1-492.4.

Pough, F.H., R.M. Andrews, J.E. Cadle, M.L. Crump, A.H. Savitzky, and K.D. Wells. 2001. Herpetology. Second edition. Prentice-Hall, Inc., Upper Saddle River, New Jersey. 612pp.

Stebbins, R.C. 2003. A field guide to western reptiles and amphibians. 3rd Edition. Houghton Mifflin Co., Boston, Massachusetts. 533pp.

Tanner, W.W. 1987. Lizards and turtles of western Chihuahua. Great Basin Naturalist 47(3):383-421.

Taylor, T. 1985. Life History Notes: Eumeces callicephalus (mountain skink). Reproduction. Herpetological Review 16(1):27.

Authors: Taylor Edwards and Don Swann

Originally published in the Sonoran Herpetologist “Herpetofauna of the 100-mile Circle” 16 (6) 2003

[/vc_column_text][/vc_column][vc_column width=”1/6″][/vc_column][/vc_row][vc_row][vc_column][gap size=”30px” id=”” class=”” style=””][/vc_column][/vc_row]