Crotaphytus collaris

The common collared lizard (Crotaphytus collaris), also commonly called eastern collared lizard, Oklahoma collared lizard, 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.

DESCRIPTION

• Crotaphytus collaris can grow up to 8–15 in (20–38 cm) in total length (including the tail), with a large head and powerful jaws. 

• Males have a blue-green body with a light brown head. Females have a light brown head and body.

• 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. 

• 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.

• Moderate in size, Crotaphytus collaris have disproportionately large heads and long hind limbs. It can reach a length of 14 inches, including the tail, with males being larger than females. Hence, they are sexually dimorphic, and adult males exhibit larger and more muscular heads than females, which tend to vary in size. Used as a weapon during male combat, the head dimensions play a key role in determining dominance, territoriality, fitness, as well as mating success. In general, bigger heads are associated with greater jaw strength and thus, bite force.

REPRODUCTION

• The reproductive season starts in mid-March to early April and concludes in mid-July. 

• Females and smaller individuals emerge first from hibernation, with males following around two weeks later. 

• Although lizards are considered mature and capable of breeding following their first hibernation, those that are two years and older exhibit greater reproductive success due to their larger size.

• In late May, courtship occurs between adult males and females. Subsequently, mature females, typically two years and older, produce their first clutches and lay them in a burrow or under a rock about two weeks after copulation. 

• They may then go on to produce second and sometimes even third clutches throughout June until mid-July.

•  The eggs are incubated in a temperature-dependent manner, and the incubation period may vary from 50 to 100 days. On average, clutch size can range from 4 to 6 eggs, but larger, older females can produce more.

• By August, adults begin to hibernate again, and juveniles do the same after hatching. The earliest of the clutches can hatch in mid-July, and later ones follow until mid-October. 

• Upon hatching, juveniles are fully developed and behave independently of their parents, as Crotaphytus collaris does not exhibit any parental care for their offspring.

HABITAT

• Individuals occupy a range of different habitats, from rocky desert landscapes to grasslands. 

• However, 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 remain hidden between rocks, despite their flamboyant features. 

• They can also look out for potential predators or territory intruders from the top of elevated platforms.