thumb|A male common collared lizard (Crotaphytus collaris) near Hatch Point, Utah

The common collared lizard (Crotaphytus collaris), also commonly called eastern collared lizard, Oklahoma collared lizard, mountain boomer, yellow-headed collared lizard, and collared lizard, is a North American species of lizard in the family Crotaphytidae. The common name "collared lizard" comes from the lizard's distinct coloration, which includes bands of black around the neck and shoulders that look like a collar. Males can be very colorful, with blue green bodies, yellow stripes on the tail and back, and yellow orange throats. There are five recognized subspecies.

thumb|Black-spotted collared lizard (Crotaphytus collaris melanomaculatus) at [[Phoenix Zoo.]]

Etymology

The subspecific name, baileyi, is in honor of American mammalogist Vernon Orlando Bailey.

Subspecies

Five subspecies are recognized as being valid, including the nominotypical subspecies. They are a sexually dichromatic lizard species with the adult males being more vivid and colorful than the females. Male dorsal and head color tend to range from green to tan and yellow to orange respectively, while females, overall, possess more muted body pigmentations, varying from brown to gray. However, when reproductively active during breeding seasons, females undergo a rapid color change, in which faint orange spots on their heads increase in brightness; this orange spotting reaches a maximum during egg maturation but gradually fades again after expulsion from the female's oviduct as she lays her eggs. Both males and females have two distinct black bands around their neck, providing additional context to their name, the common collared lizards.

Similar to adult females, juveniles also exhibit dull body colorations compared to adult males, but a key distinction is that the young have pronounced, dark brown markings that eventually fade as they grow and mature. Consequently, juvenile collared lizards lose this sharp cross-band pattern, and their features drastically change to resemble those of either adult males or females.

Like many other lizards, including the frilled lizard and basilisk, the collared lizard can run on its hind legs, and is a relatively fast sprinter. Record speeds have been around , much slower than the world record for lizards () attained by the larger-bodied Costa Rican spiny-tailed iguana, Ctenosaura similis.

Geographic range and habitat

C. collaris is chiefly found in dry, open regions of Mexico and the south-central United States including Arizona, Arkansas, Colorado, Kansas, Missouri, New Mexico, Oklahoma, and Texas. The full extent of its habitat in the United States ranges from the Ozark Mountains to Western Arizona.

C. collaris is distributed across the Southwestern United States and extend to Northern Mexico as well. Individuals occupy a range of different habitats from rocky desert landscapes to grasslands, but they often prefer to inhabit mountainous regions with high environmental temperatures for optimal thermoregulation. In addition, the hilly topography allows these keen and highly alert lizards to stay hidden between rocks, despite their flamboyant features, and look out for potential predators or territory intruders from the top of elevated platforms.

Diet

As obligate carnivores, they consume insects and small vertebrates as their main diet. Their stomachs are too small to accommodate the amount of flowers, shrubs, herbs, etc. that would be needed to maintain a constant body weight.

Diet can also vary depending on age, sex, as well as seasonal changes. In the case of younger lizards, they consume the same kinds of foods, specifically insect species, that adults do, but since younger lizards and adults differ in body size and weight, the amount of food intake tends to vary. On the other hand, male and female adults are similar in terms of their sizes and the amounts of food ingested but exhibit drastic differences in the kinds of foods that they eat. they are active during the day, and spend most of their time basking on top of elevated rocks or boulders. As a highly territorial species, they remain hyper-vigilant, scanning for predators or intruders, ready to sprint or fight when necessary. Generally, males are more active than females, as the former engage in more chase, fight, display, and courtship behaviors while the latter exhibit basking and foraging behaviors. The collared lizard in the wild has been the subject of a number of studies of sexual selection; in captivity if two males are placed in the same cage they will fight to the death. Females, on the other hand, do not demonstrate aggressive behaviors as frequently as males, experiencing less intra-species competition with other females. These territories provide ample resources and shelter the harem of females claimed and protected by the male territory owners. However, when agonistic interactions between male rivals escalate to violent fights, both lizards must expend substantial amounts of energy and risk getting seriously injured. Thus, though males do actively exclude other males from territories, they do so without resorting to physical and unfavorable conflict. Instead, they partake in social displays, either at a distance or proximally from their competitors to advertise their superiority. Surprisingly, both types of social encounters, in which males perform push ups and compressions and elevations of the trunk with the dewlap extended, Thus, when nearby residents approach an owner's shared territorial boundaries, the owner will recognize this individual and only engage in aggressive behaviors, usually in the form of a costly fight, if a threat to its territory is perceived. The variability in head size gives rise to differential jaw strength and bite force in males, which ultimately results in intra-species selection against smaller headed males.

During courtship rituals, a male or a female lizard approaches the opposite sex within 1 body length and subsequently engages in various behavioral patterns, which include either individual superimposing its limbs, torso, or tail over its partner, mounting the dorsum of the other lizard, males nudging females with their snouts or grasping them with their jaws, and mutual displays.

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File:Crotaphytus collaris, Eastern collared lizard, Tamaulipas.jpg|Eastern collared lizard (Crotaphytus collaris melanomaculatus), sub-adult photographed in situ, municipality of Miquihuana, Tamaulipas, Mexico (19 September 2007)

File:Common_Collared_Lizard_at_Wichita_Mountains_National_Wildlife_Refuge_in_Oklahoma.JPG|Male collared lizard, with blue-green body and yellow-brown head, at the Wichita Mountains Wildlife Refuge near Lawton, Oklahoma

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References

Further reading

  • Axtell RW, Webb RG (1995). "Two new Crotaphytus from southern Coahuila and the adjacent states of east-central Mexico". Bulletin of the Chicago Academy of Sciences 16 (2): 1–15. (Crotaphytus collaris melanomaculatus, new subspecies).
  • Fitch HS, Tanner WW (1951). "Remarks Concerning the Systematics of the Collared Lizard, (Crotaphytus collaris), with a Description of a New Subspecies". Transactions of the Kansas Academy of Science 54 (4): 548–559. (Crotaphytus collaris auriceps, new subspecies).
  • Ingram W, Tanner WW (1971). "A taxonomic study of Crotaphytus collaris between the Rio Grande and Colorado Rivers". Brigham Young University Science Bulletin 13 (2): 1–29. (Crotaphytus collaris fuscus, new subspecies).
  • Powell R, Conant R, Collins JT (2016). Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, Fourth Edition. Boston and New York: Houghton Mifflin Harcourt. 494 pp., 47 plates, 207 figures. . (Crotaphytus collaris, pp. 276–277, Figure 132 + Plate 24).
  • Say T (1823). In: James E (1823). Account of an Expedition from Pittsburgh to the Rocky Mountains, Performed in the Years 1819 and '20, by order of the Hon. J.C. Calhoun, Sec'y of War: Under the Command of Major Stephen H. Long. From the Notes of Major Long, Mr. T. Say, and other Gentlemen of the Exploring Party. Vol. II. Philadelphia: H.C. Carey and I. Lea. 442 pp. (Agama collaris, new species, p. 252).
  • Smith HM, Brodie ED Jr (1982). Reptiles of North America: A Guide to Field Identification. New York: Golden Press. 240 pp. (paperback), (hardcover). (Crotaphytus collaris, pp. 106–107).
  • Stejneger L (1890). "Annotated List of Reptiles and Batrachians Collected by Dr. C. Hart Merriam and Vernon Bailey on the San Francisco Mountain Plateau and Desert of the Little Colorado, Arizona, with Descriptions of New Species". North American Fauna (3): 103–118. (Crotaphytus baileyi, new species, pp. 103–105 + Plate XII, figure 1).).

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