Eastern Collared Lizard (Crotaphytus collaris)

Photo by Robert L. Bezy and and Kathryn Bolles

Eastern Collard Lizard. Photo by Robert L. Bezy and and Kathryn Bolles.

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The Eastern Collared Lizard is of moderate size (<118 mm SVL, 356 mm total length). The hind limbs and tail are relatively long, the tail is round in cross-section, and the head is proportionally large and triangular in the dorsal view. The neck is distinctly narrowed and a gular fold is present.  The dorsal scales are granular; the ventral scales are somewhat larger. Males grow to a slightly larger size and their heads are broader and more heavily muscled than the females. Also, males usually have somewhat enlarged postanal scales. There is typically black on the lining of the mouth and throat.  On the neck are two dark collars, neither of which is complete ventrally.  The anterior collar is incomplete along the mid-dorsal line and the posterior color is sometimes incomplete.  No subspecies are currently recognized.

Color patterns vary by age, sex, and breeding status.  The dorsal pattern of the adult male is highly variable; the background color may be green, turquoise, olive, brown, tan or yellow overlain with spots and faint banding.  Yellow is often present on the head and forelimbs during the breeding season.  The coloration on the dorsum of the adult female is muted compared to the male, but bright orange and or red coloration develop on the sides and neck when lizards are gravid.  These colors fade after egg deposition. Juveniles tend to be more banded than adults, and juvenile males develop orange or red coloration, similar to adult females.  Juvenile females are drab compared to other age classes and males.

The only other collared lizard found within the 100-Mile Circle is the Sonoran Collared Lizard (Crotaphytus nebrius).  Its distribution lies generally to the west and south of that of the Eastern Collared Lizard. The ranges of the two species are in close proximity in the Tucson area, where the Eastern Collared Lizard occurs in the Rincon, Santa Catalina, Tortolita, and Santa Rita mountains, and the Sonoran Collared Lizard occurs in the Waterman, Silverbell, and Tucson mountains, and at Black Mountain to the south of Tucson.  The Sonoran Collared Lizard generally occurs to lower elevations, as well (probably to about 300 m in the Circle), whereas the lowest elevations for the Eastern Collared Lizard in the Circle are about 840 m.  In the Circle, the Sonoran Collared Lizard is also almost exclusively an inhabitant of Sonoran desertscrub (but it can be found in isolated patches of semi-desert grassland atop desert mountains), whereas the Eastern Collared Lizard occurs in a variety of vegetation communities.

The two species are also generally diagnosable based on adult male colors and patterns.  In the adult male Sonoran Collared Lizard, the anterior dark collar is complete ventrally through the gular region.  Furthermore, Sonoran Collared Lizards usually have a gray background color and lack distinctive green or blue in the dorsal pattern (there may be hints of grayish-blue in the center of the back).  Although geographically disjunct and diagnosable by color and pattern, a recent molecular genetics study found that the Sonoran Collared Lizard is polyphyletic and partially imbedded within the Eastern Collared Lizard. These findings may be explained by incomplete lineage sorting and recent introgressive hybridization, but the Sonoran Collared Lizard may not be a valid species (McGuire et al. 2007).

In the 100-Mile Circle, the Eastern Collared Lizard occurs from Horseshoe Dam and Roosevelt Lake south through the Superstition Mountains to the Tortolitas, the lower slopes of the Santa Catalina and Santa Rita mountains, and eastward through Cochise County and northeast to Graham County at elevations of 840 to at least 1675 m (in the Whetsone Mountains).  It also occurs in northeastern Sonora. At its western limits in our area, it is found in rich Sonoran desertscrub, and to the east it occurs in semi-desert grassland, Plains grassland, Chihuahuan desertscrub, and the lower limits of oak savanna. It has been found as high as 2750 m in New Mexico.  The Eastern Collared Lizard is almost always associated with rocks, often on slopes in montane canyons, but also on outcrops in more level terrain.  They are often seen basking atop boulders or rocks, and adult males are highly territorial.  Throughout its range, the Eastern Collared Lizard occurs from Illinois, Missouri and Arkansas west to Nevada and Arizona and southward to San Luis Potosí and Zacatecas, Mexico.

Age to maturation and number of clutches per year vary over the extensive range of the species.  Individuals typically reach maturation within their first year of life in the south, but more frequently in their second year in northern populations.  In our area, males and females likely mature at about 76-83 and 64 mm SVL, respectively. Two to three clutches per year is probably the norm in the south, but northern populations typically produce only one clutch.  Reproduction has not been specifically studied in Arizona, but based on work in adjacent areas, mating likely takes place in April and May, and clutches of 1-24 eggs (mean=5.3 in southern New Mexico, Parker 1973) are laid in late April to mid-June.  Hatchlings, which are 34-42 mm SVL, appear in mid August into September.

In central New Mexico, the most important dietary items by frequency were (from greatest to least by percentage) grasshoppers, ants and wasps, spiders, true bugs, flies, and butterflies and moths (Best and Pfaffenberger 1987).  Eastern Collared Lizards also eat other lizards, a snake was reported in the diet once, and plants are occasionally consumed. Animal prey is detected by motion.

The Eastern Collared Lizard is listed as a species of least concern on the 2013 IUCN Red List.  Four can be captured per year or held in possession with a valid Arizona hunting license, although take of this species is prohibited without special authorization in protected areas such as National Park Service units and National Wildlife Refuges.

Suggested Reading:

Ballinger, R.E., and T.G. Hipp. 1985. Reproduction in the collared lizard, Crotaphytus collaris, in west-central Texas. Copeia 1985:976-980.

Best, T.L., and G.S. Pfaffenberger. 1987. Age and sexual variation in the diet of collared lizards (Crotaphytus collaris). Southwestern Naturalist 32:415-426.

Brennan, T.C., and A.T. Holycross. 2006. Amphibians and Reptiles in Arizona. Arizona Game and Fish Department, Phoenix, AZ.

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

Ivanyi, C. 2009. Eastern Collared Lizard, Crotaphytus collaris (Say, 1823). Pages 104-107 in Jones, L.L.C., and R.E. Lovich (eds.), Lizards of the American Southwest: A Photographic Field Guide.  Rio Nuevo Publishers, Tucson, Arizona.

McGuire, J.A., C.W. Linkem, M.S. Koo, D.W. Hutchison, A.K. Lappin, D.I. Orange, J. Lemos-Espinal, B.R. Riddle, and J.R. Jaeger. 2007. Mitochondrial introgression and incomplete lineage sorting through space and time: phyllogenetics of Crotaphytid lizards. Evolution 61-12: 2879–2897.

Parker, W.S. 1973. Notes on reproduction of some lizards from Arizona, New Mexico, Texas, and Utah. Herpetologica 29:258-264.

Author: Jim Rorabaugh


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